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| author | Franklin Schmidt <fschmidt@gmail.com> |
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| date | Fri, 24 Apr 2015 14:05:52 -0600 |
| parents | 497d4ef0a89f |
| children | a7cb58532846 |
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1 local Io = require "luan:Io" |
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2 local Html = require "luan:Html" |
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3 local Http = require "luan:web/Http" |
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4 local Shared = require "site:/Shared" |
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5 |
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6 |
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7 function service() |
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8 Io.stdout = Http.response.text_writer() |
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9 %> |
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10 <html> |
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11 <head> |
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12 <% Html.simply_html_head() %> |
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13 <title>Luan Reference Manual</title> |
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14 </head> |
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15 <body> |
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16 |
| 372 | 17 <div container> |
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18 <% Shared.header() %> |
| 372 | 19 |
| 20 <h1>Luan Reference Manual</h1> | |
| 21 | |
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22 <p> |
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23 <small> |
| 372 | 24 Original copyright © 2015 Lua.org, PUC-Rio. |
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25 Freely available under the terms of the |
| 372 | 26 <a href="http://www.lua.org/license.html">Lua license</a>. |
| 27 Modified for Luan. | |
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28 </small> |
| 372 | 29 </p> |
| 30 | |
| 31 <hr/> | |
| 32 | |
| 33 <h2>Contents</h2> | |
| 34 | |
| 35 <div margin-bottom="1em"><a href="#intro">Introduction</a></div> | |
| 36 | |
| 373 | 37 <div margin-bottom="1em"> |
| 38 <a href="#basic">Basic Concepts</a> | |
| 39 <ul> | |
| 40 <li><a href="#types">Values and Types</a></li> | |
| 41 <li><a href="#env">Environments</a></li> | |
| 42 <li><a href="#error">Error Handling</a></li> | |
| 43 <li><a href="#meta">Metatables and Metamethods</a></li> | |
| 380 | 44 <li><a href="#gc">Garbage Collection</a></li> |
| 45 </ul> | |
| 46 </div> | |
| 47 | |
| 48 <div margin-bottom="1em"> | |
| 49 <a href="#lang">The Language</a> | |
| 50 <ul> | |
| 51 <li><a href="#lex">Lexical Conventions</a></li> | |
| 52 <li><a href="#vars">Variables</a></li> | |
| 389 | 53 <li> |
| 54 <a href="#stmts">Statements</a> | |
| 55 <ul> | |
| 56 <li><a href="#blocks">Blocks</a></li> | |
| 57 </ul> | |
| 58 </li> | |
| 373 | 59 </ul> |
| 60 </div> | |
| 61 | |
| 372 | 62 <hr/> |
| 63 | |
| 373 | 64 |
| 372 | 65 <h2 margin-top="1em"><a name="intro">Introduction</a></h2> |
| 66 | |
| 67 <p>Luan is a high level programming language based on <a href="http://www.lua.org">Lua</a>. A great strength of Lua is its simplicity and Luan takes this even further, being even simpler than Lua. The goal is to provide a simple programming language for the casual programmer with as few concepts as possible so that one can quickly learn the language and then easily understand any code written in Luan.</p> | |
| 68 | |
| 69 <p>Luan is implemented in Java and is tightly coupled with Java. So it makes a great scripting language for Java programmers.</p> | |
| 70 | |
| 71 <p>Unlike Lua which is meant to be embedded, Luan is meant to be a full scripting language. This done not by adding feature to Luan, but rather by providing a complete set of libraries.</p> | |
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72 |
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73 |
| 373 | 74 <h2 margin-top="1em"><a name="basic">Basic Concepts</a></h2> |
| 75 | |
| 76 <p>This section describes the basic concepts of the language.</p> | |
| 77 | |
| 78 <h3 margin-top="1em"><a name="types">Values and Types</a></h3> | |
| 79 | |
| 80 <p> | |
| 81 Luan is a <i>dynamically typed language</i>. | |
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82 This means that |
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83 variables do not have types; only values do. |
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84 There are no type definitions in the language. |
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85 All values carry their own type. |
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86 |
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87 |
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88 <p> |
| 373 | 89 All values in Luan are <i>first-class values</i>. |
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90 This means that all values can be stored in variables, |
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91 passed as arguments to other functions, and returned as results. |
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92 |
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93 |
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94 <p> |
| 373 | 95 There are eight basic types in Luan: |
| 96 <i>nil</i>, <i>boolean</i>, <i>number</i>, | |
| 97 <i>string</i>, <i>binary</i>, <i>function</i>, <i>userdata</i>, | |
| 98 and <i>table</i>. | |
| 99 <i>Nil</i> is the type of the value <b>nil</b>, | |
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100 whose main property is to be different from any other value; |
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101 it usually represents the absence of a useful value. |
| 373 | 102 <i>Nil</i> is implemented as the Java value <i>null</i>. |
| 103 <i>Boolean</i> is the type of the values <b>false</b> and <b>true</b>. | |
| 104 <i>Boolean</i> is implemented as the Java class <i>Boolean</i>. | |
| 105 <i>Number</i> represents both | |
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106 integer numbers and real (floating-point) numbers. |
| 373 | 107 <i>Number</i> is implemented as the Java class <i>Number</i>. Any Java subclass of <i>Number</i> is allowed and this is invisible to the Luan user. Operations on numbers follow the same rules of |
| 108 the underlying Java implementation. | |
| 109 | |
| 110 <i>String</i> is implemented as the Java class <i>String</i>. | |
| 111 <i>Binary</i> is implemented as the Java type <i>byte[]</i>. | |
| 112 | |
| 113 | |
| 114 <p> | |
| 115 Luan can call (and manipulate) functions written in Luan and | |
| 116 functions written in Java (see <a href="#3.4.10">§3.4.10</a>). | |
| 117 Both are represented by the type <i>function</i>. | |
| 118 | |
| 119 | |
| 120 <p> | |
| 121 The type <i>userdata</i> is provided to allow arbitrary Java objects to | |
| 122 be stored in Luan variables. | |
| 123 A userdata value is a Java object that isn't one of the standard Luan types. | |
| 124 Userdata has no predefined operations in Luan, | |
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125 except assignment and identity test. |
| 373 | 126 Userdata is useful then Java access is enabled in Luan |
| 127 | |
| 128 | |
| 129 | |
| 130 <p> | |
| 131 The type <i>table</i> implements associative arrays, | |
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132 that is, arrays that can be indexed not only with numbers, |
| 373 | 133 but with any Luan value except <b>nil</b>. |
| 134 Tables can be <i>heterogeneous</i>; | |
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135 that is, they can contain values of all types (except <b>nil</b>). |
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136 Any key with value <b>nil</b> is not considered part of the table. |
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137 Conversely, any key that is not part of a table has |
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138 an associated value <b>nil</b>. |
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139 |
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140 |
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141 <p> |
| 373 | 142 Tables are the sole data-structuring mechanism in Luan; |
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143 they can be used to represent ordinary arrays, sequences, |
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144 symbol tables, sets, records, graphs, trees, etc. |
| 373 | 145 To represent records, Luan uses the field name as an index. |
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146 The language supports this representation by |
| 373 | 147 providing <tt>a.name</tt> as syntactic sugar for <tt>a["name"]</tt>. |
| 148 There are several convenient ways to create tables in Luan | |
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149 (see <a href="#3.4.9">§3.4.9</a>). |
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150 |
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151 |
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152 <p> |
| 373 | 153 We use the term <i>sequence</i> to denote a table where |
| 154 the set of all positive numeric keys is equal to {1..<i>n</i>} | |
| 155 for some non-negative integer <i>n</i>, | |
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156 which is called the length of the sequence (see <a href="#3.4.7">§3.4.7</a>). |
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157 |
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158 |
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159 <p> |
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160 Like indices, |
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161 the values of table fields can be of any type. |
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162 In particular, |
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163 because functions are first-class values, |
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164 table fields can contain functions. |
| 373 | 165 Thus tables can also carry <i>methods</i> (see <a href="#3.4.11">§3.4.11</a>). |
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166 |
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167 |
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168 <p> |
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169 The indexing of tables follows |
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170 the definition of raw equality in the language. |
| 373 | 171 The expressions <tt>a[i]</tt> and <tt>a[j]</tt> |
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172 denote the same table element |
| 373 | 173 if and only if <tt>i</tt> and <tt>j</tt> are raw equal |
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174 (that is, equal without metamethods). |
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175 In particular, floats with integral values |
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176 are equal to their respective integers |
| 373 | 177 (e.g., <tt>1.0 == 1</tt>). |
| 178 | |
| 179 | |
| 180 <p> | |
| 181 Luan values are <i>objects</i>: | |
| 182 variables do not actually <i>contain</i> values, | |
| 183 only <i>references</i> to them. | |
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184 Assignment, parameter passing, and function returns |
| 373 | 185 always manipulate references to values; |
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186 these operations do not imply any kind of copy. |
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187 |
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188 |
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189 <p> |
| 373 | 190 The library function <a href="#pdf-type"><tt>Luan.type</tt></a> returns a string describing the type |
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191 of a given value (see <a href="#6.1">§6.1</a>). |
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192 |
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193 |
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194 |
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195 |
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196 |
| 373 | 197 <h3 margin-top="1em"><a name="env">Environments</a></h3> |
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198 |
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199 <p> |
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200 As will be discussed in <a href="#3.2">§3.2</a> and <a href="#3.3.3">§3.3.3</a>, |
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201 any reference to a free name |
| 373 | 202 (that is, a name not bound to any declaration) <tt>var</tt> |
| 203 is syntactically translated to <tt>_ENV.var</tt>. | |
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204 Moreover, every chunk is compiled in the scope of |
| 373 | 205 an external local variable named <tt>_ENV</tt> (see <a href="#3.3.2">§3.3.2</a>), |
| 206 so <tt>_ENV</tt> itself is never a free name in a chunk. | |
| 207 | |
| 208 | |
| 209 <p> | |
| 210 Despite the existence of this external <tt>_ENV</tt> variable and | |
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211 the translation of free names, |
| 373 | 212 <tt>_ENV</tt> is a completely regular name. |
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213 In particular, |
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214 you can define new variables and parameters with that name. |
| 373 | 215 Each reference to a free name uses the <tt>_ENV</tt> that is |
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216 visible at that point in the program, |
| 373 | 217 following the usual visibility rules of Luan (see <a href="#3.5">§3.5</a>). |
| 218 | |
| 219 | |
| 220 <p> | |
| 221 Any table used as the value of <tt>_ENV</tt> is called an <i>environment</i>. | |
| 222 | |
| 223 | |
| 224 <p> | |
| 225 When Luan loads a chunk, | |
| 226 the default value for its <tt>_ENV</tt> is an empty table. | |
| 227 | |
| 228 <p> | |
| 229 Luan also provides all chunks with two other local values: <tt>require</tt> and <tt>java</tt>. These are functions used to load and access libraries and other modules. | |
| 230 | |
| 231 | |
| 232 | |
| 233 | |
| 234 <h3 margin-top="1em"><a name="error">Error Handling</a></h3> | |
| 235 | |
| 236 <p> | |
| 237 Luan code can explicitly generate an error by calling the | |
| 238 <a href="#pdf-error"><tt>error</tt></a> function. | |
| 239 If you need to catch errors in Luan, | |
| 240 you can use <a href="#pdf-pcall"><tt>pcall</tt></a> or <a href="#pdf-xpcall"><tt>try</tt></a> | |
| 241 to call a given function in <i>protected mode</i>. | |
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242 |
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243 |
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244 <p> |
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245 Whenever there is an error, |
| 373 | 246 an <i>error object</i> (also called an <i>error message</i>) |
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247 is propagated with information about the error. |
| 373 | 248 Luan itself only generates errors whose error object is a string, |
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249 but programs may generate errors with |
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250 any value as the error object. |
| 373 | 251 It is up to the Luan program or its host to handle such error objects. |
| 252 | |
| 253 | |
| 254 | |
| 255 | |
| 256 | |
| 257 <h3 margin-top="1em"><a name="meta">Metatables and Metamethods</a></h3> | |
| 258 | |
| 259 <p> | |
| 260 Every table in Luan can have a <i>metatable</i>. | |
| 261 This <i>metatable</i> is an ordinary Luan table | |
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262 that defines the behavior of the original value |
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263 under certain special operations. |
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264 You can change several aspects of the behavior |
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265 of operations over a value by setting specific fields in its metatable. |
| 373 | 266 For instance, when a table is the operand of an addition, |
| 267 Luan checks for a function in the field "<tt>__add</tt>" of the table's metatable. | |
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268 If it finds one, |
| 373 | 269 Luan calls this function to perform the addition. |
| 270 | |
| 271 | |
| 272 <p> | |
| 273 The keys in a metatable are derived from the <i>event</i> names; | |
| 274 the corresponding values are called <ii>metamethods</i>. | |
| 275 In the previous example, the event is <tt>"add"</tt> | |
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276 and the metamethod is the function that performs the addition. |
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277 |
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278 |
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279 <p> |
| 373 | 280 You can query the metatable of any table |
| 281 using the <a href="#pdf-getmetatable"><tt>get_metatable</tt></a> function. | |
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282 |
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283 |
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284 <p> |
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285 You can replace the metatable of tables |
| 373 | 286 using the <a href="#pdf-setmetatable"><tt>set_metatable</tt></a> function. |
| 287 | |
| 288 | |
| 289 <p> | |
| 290 A metatable controls how a table behaves in | |
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291 arithmetic operations, bitwise operations, |
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292 order comparisons, concatenation, length operation, calls, and indexing. |
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293 |
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294 |
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295 <p> |
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296 A detailed list of events controlled by metatables is given next. |
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297 Each operation is identified by its corresponding event name. |
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298 The key for each event is a string with its name prefixed by |
| 373 | 299 two underscores, '<tt>__</tt>'; |
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300 for instance, the key for operation "add" is the |
| 373 | 301 string "<tt>__add</tt>". |
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302 Note that queries for metamethods are always raw; |
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303 the access to a metamethod does not invoke other metamethods. |
| 373 | 304 You can emulate how Luan queries a metamethod for an object <tt>obj</tt> |
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305 with the following code: |
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306 |
| 382 | 307 <p><tt><pre> |
| 373 | 308 raw_get(get_metatable(obj) or {}, "__" .. event_name) |
| 382 | 309 </pre></tt></p> |
| 373 | 310 |
| 311 <p> | |
| 312 Here are the events: | |
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313 |
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314 <ul> |
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315 |
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316 <li><b>"add": </b> |
| 373 | 317 the <tt>+</tt> operation. |
| 318 | |
| 319 If any operand for an addition is a table, | |
| 320 Luan will try to call a metamethod. | |
| 321 First, Luan will check the first operand (even if it is valid). | |
| 322 If that operand does not define a metamethod for the "<tt>__add</tt>" event, | |
| 323 then Luan will check the second operand. | |
| 324 If Luan can find a metamethod, | |
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325 it calls the metamethod with the two operands as arguments, |
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326 and the result of the call |
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327 (adjusted to one value) |
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328 is the result of the operation. |
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329 Otherwise, |
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330 it raises an error. |
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331 </li> |
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332 |
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333 <li><b>"sub": </b> |
| 373 | 334 the <tt>-</tt> operation. |
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335 |
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336 Behavior similar to the "add" operation. |
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337 </li> |
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338 |
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339 <li><b>"mul": </b> |
| 373 | 340 the <tt>*</tt> operation. |
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341 |
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342 Behavior similar to the "add" operation. |
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343 </li> |
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344 |
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345 <li><b>"div": </b> |
| 373 | 346 the <tt>/</tt> operation. |
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347 |
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348 Behavior similar to the "add" operation. |
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349 </li> |
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350 |
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351 <li><b>"mod": </b> |
| 373 | 352 the <tt>%</tt> operation. |
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353 |
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354 Behavior similar to the "add" operation. |
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355 </li> |
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356 |
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357 <li><b>"pow": </b> |
| 373 | 358 the <tt>^</tt> (exponentiation) operation. |
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359 |
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360 Behavior similar to the "add" operation. |
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361 </li> |
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362 |
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363 <li><b>"unm": </b> |
| 373 | 364 the <tt>-</tt> (unary minus) operation. |
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365 |
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366 Behavior similar to the "add" operation. |
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367 </li> |
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368 |
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369 <li><b>"concat": </b> |
| 373 | 370 the <tt>..</tt> (concatenation) operation. |
| 371 | |
| 372 Behavior similar to the "add" operation. | |
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371
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373 </li> |
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374 |
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375 <li><b>"len": </b> |
| 373 | 376 the <tt>#</tt> (length) operation. |
| 377 | |
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378 If there is a metamethod, |
| 373 | 379 Luan calls it with the object as argument, |
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380 and the result of the call |
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381 (always adjusted to one value) |
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382 is the result of the operation. |
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383 If there is no metamethod but the object is a table, |
| 373 | 384 then Luan uses the table length operation (see <a href="#3.4.7">§3.4.7</a>). |
| 385 Otherwise, Luan raises an error. | |
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386 </li> |
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387 |
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388 <li><b>"eq": </b> |
| 373 | 389 the <tt>==</tt> (equal) operation. |
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390 |
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391 Behavior similar to the "add" operation, |
| 373 | 392 except that Luan will try a metamethod only when the values |
| 393 being compared are both tables | |
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394 and they are not primitively equal. |
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395 The result of the call is always converted to a boolean. |
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396 </li> |
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397 |
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398 <li><b>"lt": </b> |
| 373 | 399 the <tt><</tt> (less than) operation. |
| 400 | |
| 401 Behavior similar to the "add" operation. | |
|
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402 The result of the call is always converted to a boolean. |
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403 </li> |
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404 |
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405 <li><b>"le": </b> |
| 373 | 406 the <tt><=</tt> (less equal) operation. |
|
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407 |
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408 Unlike other operations, |
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409 The less-equal operation can use two different events. |
| 373 | 410 First, Luan looks for the "<tt>__le</tt>" metamethod in both operands, |
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411 like in the "lt" operation. |
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412 If it cannot find such a metamethod, |
| 373 | 413 then it will try the "<tt>__lt</tt>" event, |
| 414 assuming that <tt>a <= b</tt> is equivalent to <tt>not (b < a)</tt>. | |
|
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415 As with the other comparison operators, |
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416 the result is always a boolean. |
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417 </li> |
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418 |
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419 <li><b>"index": </b> |
| 373 | 420 The indexing access <tt>table[key]</tt>. |
| 421 | |
| 422 This event happens | |
| 423 when <tt>key</tt> is not present in <tt>table</tt>. | |
| 424 The metamethod is looked up in <tt>table</tt>. | |
|
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425 |
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426 |
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427 <p> |
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428 Despite the name, |
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429 the metamethod for this event can be either a function or a table. |
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430 If it is a function, |
| 373 | 431 it is called with <tt>table</tt> and <tt>key</tt> as arguments. |
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432 If it is a table, |
| 373 | 433 the final result is the result of indexing this table with <tt>key</tt>. |
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434 (This indexing is regular, not raw, |
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435 and therefore can trigger another metamethod.) |
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436 </li> |
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437 |
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438 <li><b>"newindex": </b> |
| 373 | 439 The indexing assignment <tt>table[key] = value</tt>. |
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440 |
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441 Like the index event, |
| 373 | 442 this event happens when |
| 443 when <tt>key</tt> is not present in <tt>table</tt>. | |
| 444 The metamethod is looked up in <tt>table</tt>. | |
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445 |
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446 |
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447 <p> |
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448 Like with indexing, |
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449 the metamethod for this event can be either a function or a table. |
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450 If it is a function, |
| 373 | 451 it is called with <tt>table</tt>, <tt>key</tt>, and <tt>value</tt> as arguments. |
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452 If it is a table, |
| 373 | 453 Luan does an indexing assignment to this table with the same key and value. |
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454 (This assignment is regular, not raw, |
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455 and therefore can trigger another metamethod.) |
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456 |
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457 |
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458 <p> |
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459 Whenever there is a "newindex" metamethod, |
| 373 | 460 Luan does not perform the primitive assignment. |
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461 (If necessary, |
| 373 | 462 the metamethod itself can call <a href="#pdf-rawset"><tt>raw_set</tt></a> |
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463 to do the assignment.) |
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464 </li> |
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465 |
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466 <li><b>"call": </b> |
| 373 | 467 The call operation <tt>func(args)</tt>. |
| 468 | |
| 469 This event happens when Luan tries to call a table. | |
| 470 The metamethod is looked up in <tt>func</tt>. | |
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471 If present, |
| 373 | 472 the metamethod is called with <tt>func</tt> as its first argument, |
| 473 followed by the arguments of the original call (<tt>args</tt>). | |
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474 </li> |
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475 |
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476 </ul> |
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477 |
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478 |
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479 |
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480 |
| 380 | 481 <h3 margin-top="1em"><a name="gc">Garbage Collection</a></h3> |
| 482 | |
| 483 <p> | |
| 484 Luan uses Java's garbage collection. | |
| 485 | |
| 486 | |
| 487 | |
| 488 | |
| 489 | |
| 490 <h2 margin-top="1em"><a name="lang">The Language</a></h2> | |
| 491 | |
| 492 <p> | |
| 493 This section describes the lexis, the syntax, and the semantics of Luan. | |
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494 In other words, |
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495 this section describes |
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496 which tokens are valid, |
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497 how they can be combined, |
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498 and what their combinations mean. |
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499 |
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500 |
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501 <p> |
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502 Language constructs will be explained using the usual extended BNF notation, |
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503 in which |
| 380 | 504 {<i>a</i>} means 0 or more <i>a</i>'s, and |
| 505 [<i>a</i>] means an optional <i>a</i>. | |
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506 Non-terminals are shown like non-terminal, |
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507 keywords are shown like <b>kword</b>, |
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508 and other terminal symbols are shown like ‘<b>=</b>’. |
| 380 | 509 The complete syntax of Luan can be found in <a href="#9">§9</a> |
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510 at the end of this manual. |
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511 |
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512 |
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513 |
| 380 | 514 <h3 margin-top="1em"><a name="lex">Lexical Conventions</a></h3> |
| 515 | |
| 516 <p> | |
| 517 Luan ignores spaces and comments | |
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518 between lexical elements (tokens), |
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519 except as delimiters between names and keywords. |
| 380 | 520 Luan generally considers the end of a line to be the end of a statement. This catches errors and encourages readability. The exception to this is in paranthesis ( <i>(...)</i>, <i>[...]</i>, and <i>{...}</i> ) where the end of line is treated as white space. |
| 521 | |
| 522 <p> | |
| 523 <i>Names</i> | |
| 524 (also called <i>identifiers</i>) | |
| 525 in Luan can be any string of letters, | |
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526 digits, and underscores, |
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527 not beginning with a digit. |
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528 Identifiers are used to name variables, table fields, and labels. |
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529 |
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530 |
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531 <p> |
| 380 | 532 The following <i>keywords</i> are reserved |
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533 and cannot be used as names: |
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534 |
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535 |
| 389 | 536 <p><tt><pre> |
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537 and break do else elseif end |
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538 false for function goto if in |
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539 local nil not or repeat return |
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540 then true until while |
| 389 | 541 </pre></tt></p> |
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542 |
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543 <p> |
| 380 | 544 Luan is a case-sensitive language: |
| 545 <tt>and</tt> is a reserved word, but <tt>And</tt> and <tt>AND</tt> | |
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546 are two different, valid names. |
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547 |
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548 |
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549 <p> |
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550 The following strings denote other tokens: |
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551 |
| 389 | 552 <p><tt><pre> |
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553 + - * / % ^ # |
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554 & ~ | << >> // |
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555 == ~= <= >= < > = |
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556 ( ) { } [ ] :: |
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557 ; : , . .. ... |
| 389 | 558 </pre></tt></p> |
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559 |
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560 <p> |
| 380 | 561 <i>Literal strings</i> |
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562 can be delimited by matching single or double quotes, |
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563 and can contain the following C-like escape sequences: |
| 380 | 564 '<tt>\a</tt>' (bell), |
| 565 '<tt>\b</tt>' (backspace), | |
| 566 '<tt>\f</tt>' (form feed), | |
| 567 '<tt>\n</tt>' (newline), | |
| 568 '<tt>\r</tt>' (carriage return), | |
| 569 '<tt>\t</tt>' (horizontal tab), | |
| 570 '<tt>\v</tt>' (vertical tab), | |
| 571 '<tt>\\</tt>' (backslash), | |
| 572 '<tt>\"</tt>' (quotation mark [double quote]), | |
| 573 and '<tt>\'</tt>' (apostrophe [single quote]). | |
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574 A backslash followed by a real newline |
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575 results in a newline in the string. |
| 380 | 576 The escape sequence '<tt>\z</tt>' skips the following span |
|
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577 of white-space characters, |
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578 including line breaks; |
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579 it is particularly useful to break and indent a long literal string |
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580 into multiple lines without adding the newlines and spaces |
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581 into the string contents. |
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582 |
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583 |
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584 <p> |
| 380 | 585 Luan can specify any character in a literal string by its numerical value. |
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586 This can be done |
| 380 | 587 with the escape sequence <tt>\x<i>XX</i></tt>, |
| 588 where <i>XX</i> is a sequence of exactly two hexadecimal digits, | |
| 589 or with the escape sequence <tt>\<i>ddd</i></tt>, | |
| 590 where <i>ddd</i> is a sequence of up to three decimal digits. | |
|
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591 (Note that if a decimal escape sequence is to be followed by a digit, |
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592 it must be expressed using exactly three digits.) |
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593 |
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594 |
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595 <p> |
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596 Literal strings can also be defined using a long format |
| 380 | 597 enclosed by <i>long brackets</i>. |
| 598 We define an <i>opening long bracket of level <i>n</i></i> as an opening | |
| 599 square bracket followed by <i>n</i> equal signs followed by another | |
|
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600 opening square bracket. |
| 380 | 601 So, an opening long bracket of level 0 is written as <tt>[[</tt>, |
| 602 an opening long bracket of level 1 is written as <tt>[=[</tt>, | |
|
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603 and so on. |
| 380 | 604 A <i>closing long bracket</i> is defined similarly; |
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605 for instance, |
| 380 | 606 a closing long bracket of level 4 is written as <tt>]====]</tt>. |
| 607 A <i>long literal</i> starts with an opening long bracket of any level and | |
|
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608 ends at the first closing long bracket of the same level. |
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609 It can contain any text except a closing bracket of the same level. |
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610 Literals in this bracketed form can run for several lines, |
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611 do not interpret any escape sequences, |
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612 and ignore long brackets of any other level. |
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613 Any kind of end-of-line sequence |
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614 (carriage return, newline, carriage return followed by newline, |
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615 or newline followed by carriage return) |
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616 is converted to a simple newline. |
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617 |
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618 |
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619 <p> |
| 380 | 620 Any character in a literal string not |
|
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621 explicitly affected by the previous rules represents itself. |
| 380 | 622 However, Luan opens files for parsing in text mode, |
|
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623 and the system file functions may have problems with |
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624 some control characters. |
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625 So, it is safer to represent |
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626 non-text data as a quoted literal with |
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627 explicit escape sequences for non-text characters. |
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628 |
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629 |
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630 <p> |
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631 For convenience, |
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632 when the opening long bracket is immediately followed by a newline, |
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633 the newline is not included in the string. |
| 380 | 634 As an example |
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635 the five literal strings below denote the same string: |
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636 |
| 389 | 637 <p><tt><pre> |
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638 a = 'alo\n123"' |
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639 a = "alo\n123\"" |
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640 a = '\97lo\10\04923"' |
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641 a = [[alo |
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642 123"]] |
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643 a = [==[ |
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644 alo |
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645 123"]==] |
| 389 | 646 </pre></tt></p> |
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647 |
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648 <p> |
| 380 | 649 A <i>numerical constant</i> (or <i>numeral</i>) |
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650 can be written with an optional fractional part |
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651 and an optional decimal exponent, |
| 380 | 652 marked by a letter '<tt>e</tt>' or '<tt>E</tt>'. |
| 653 Luan also accepts hexadecimal constants, | |
| 654 which start with <tt>0x</tt> or <tt>0X</tt>. | |
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655 Hexadecimal constants also accept an optional fractional part |
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656 plus an optional binary exponent, |
| 380 | 657 marked by a letter '<tt>p</tt>' or '<tt>P</tt>'. |
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658 A numeric constant with a fractional dot or an exponent |
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659 denotes a float; |
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660 otherwise it denotes an integer. |
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661 Examples of valid integer constants are |
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662 |
| 389 | 663 <p><tt><pre> |
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664 3 345 0xff 0xBEBADA |
| 389 | 665 </pre></tt></p> |
| 382 | 666 |
| 667 <p> | |
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668 Examples of valid float constants are |
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669 |
| 389 | 670 <p><tt><pre> |
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671 3.0 3.1416 314.16e-2 0.31416E1 34e1 |
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672 0x0.1E 0xA23p-4 0X1.921FB54442D18P+1 |
| 389 | 673 </pre></tt></p> |
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674 |
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675 <p> |
| 380 | 676 A <i>comment</i> starts with a double hyphen (<tt>--</tt>) |
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677 anywhere outside a string. |
| 380 | 678 If the text immediately after <tt>--</tt> is not an opening long bracket, |
| 679 the comment is a <i>short comment</i>, | |
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680 which runs until the end of the line. |
| 380 | 681 Otherwise, it is a <i>long comment</i>, |
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682 which runs until the corresponding closing long bracket. |
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683 Long comments are frequently used to disable code temporarily. |
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684 |
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685 |
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686 |
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687 |
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688 |
| 380 | 689 <h3 margin-top="1em"><a name="vars">Variables</a></h3> |
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690 |
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691 <p> |
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692 Variables are places that store values. |
| 380 | 693 There are three kinds of variables in Luan: |
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694 global variables, local variables, and table fields. |
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695 |
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696 |
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697 <p> |
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698 A single name can denote a global variable or a local variable |
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699 (or a function's formal parameter, |
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700 which is a particular kind of local variable): |
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701 |
| 389 | 702 <p><tt><pre> |
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703 var ::= Name |
| 389 | 704 </pre></tt></p> |
| 382 | 705 |
| 706 <p> | |
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707 Name denotes identifiers, as defined in <a href="#3.1">§3.1</a>. |
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708 |
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709 |
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710 <p> |
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711 Any variable name is assumed to be global unless explicitly declared |
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712 as a local (see <a href="#3.3.7">§3.3.7</a>). |
| 380 | 713 Local variables are <i>lexically scoped</i>: |
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714 local variables can be freely accessed by functions |
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715 defined inside their scope (see <a href="#3.5">§3.5</a>). |
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716 |
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717 |
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718 <p> |
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719 Before the first assignment to a variable, its value is <b>nil</b>. |
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720 |
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721 |
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722 <p> |
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723 Square brackets are used to index a table: |
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724 |
| 389 | 725 <p><tt><pre> |
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726 var ::= prefixexp ‘<b>[</b>’ exp ‘<b>]</b>’ |
| 389 | 727 </pre></tt></p> |
| 382 | 728 |
| 729 <p> | |
|
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730 The meaning of accesses to table fields can be changed via metatables. |
| 380 | 731 An access to an indexed variable <tt>t[i]</tt> is equivalent to |
| 732 a call <tt>gettable_event(t,i)</tt>. | |
|
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733 (See <a href="#2.4">§2.4</a> for a complete description of the |
| 380 | 734 <tt>gettable_event</tt> function. |
| 735 This function is not defined or callable in Luan. | |
|
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736 We use it here only for explanatory purposes.) |
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737 |
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738 |
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739 <p> |
| 380 | 740 The syntax <tt>var.Name</tt> is just syntactic sugar for |
| 741 <tt>var["Name"]</tt>: | |
|
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742 |
| 389 | 743 <p><tt><pre> |
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744 var ::= prefixexp ‘<b>.</b>’ Name |
| 389 | 745 </pre></tt></p> |
|
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746 |
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747 <p> |
| 380 | 748 An access to a global variable <tt>x</tt> |
| 749 is equivalent to <tt>_ENV.x</tt>. | |
|
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750 Due to the way that chunks are compiled, |
| 380 | 751 <tt>_ENV</tt> is never a global name (see <a href="#2.2">§2.2</a>). |
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752 |
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753 |
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754 |
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755 |
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756 |
| 389 | 757 <h3 margin-top="1em"><a name="stmts">Statements</a></h3> |
| 758 | |
| 759 <p> | |
| 760 Luan supports an almost conventional set of statements, | |
|
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761 similar to those in Pascal or C. |
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762 This set includes |
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763 assignments, control structures, function calls, |
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764 and variable declarations. |
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765 |
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766 |
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767 |
| 389 | 768 <h3 margin-top="1em"><a name="blocks">Blocks</a></h3> |
|
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769 |
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770 <p> |
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771 A block is a list of statements, |
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772 which are executed sequentially: |
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773 |
| 389 | 774 <p><tt><pre> |
|
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775 block ::= {stat} |
| 389 | 776 </pre></tt></p> |
| 777 | |
| 778 <p> | |
| 779 Luan has <i>empty statements</i> | |
|
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780 that allow you to separate statements with semicolons, |
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781 start a block with a semicolon |
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782 or write two semicolons in sequence: |
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783 |
| 389 | 784 <p><tt><pre> |
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785 stat ::= ‘<b>;</b>’ |
| 389 | 786 </pre></tt></p> |
|
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787 |
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788 <p> |
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789 A block can be explicitly delimited to produce a single statement: |
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790 |
| 389 | 791 <p><tt><pre> |
|
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792 stat ::= <b>do</b> block <b>end</b> |
| 389 | 793 </pre></tt></p> |
| 794 | |
| 795 <p> | |
|
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796 Explicit blocks are useful |
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797 to control the scope of variable declarations. |
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798 Explicit blocks are also sometimes used to |
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799 add a <b>return</b> statement in the middle |
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800 of another block (see <a href="#3.3.4">§3.3.4</a>). |
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801 |
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802 |
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803 |
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804 |
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805 |
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806 <h3>3.3.2 – <a name="3.3.2">Chunks</a></h3> |
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807 |
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808 <p> |
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809 The unit of compilation of Lua is called a <em>chunk</em>. |
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810 Syntactically, |
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811 a chunk is simply a block: |
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812 |
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813 <pre> |
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814 chunk ::= block |
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815 </pre> |
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816 |
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817 <p> |
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818 Lua handles a chunk as the body of an anonymous function |
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819 with a variable number of arguments |
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820 (see <a href="#3.4.11">§3.4.11</a>). |
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821 As such, chunks can define local variables, |
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822 receive arguments, and return values. |
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823 Moreover, such anonymous function is compiled as in the |
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824 scope of an external local variable called <code>_ENV</code> (see <a href="#2.2">§2.2</a>). |
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825 The resulting function always has <code>_ENV</code> as its only upvalue, |
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826 even if it does not use that variable. |
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827 |
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828 |
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829 <p> |
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830 A chunk can be stored in a file or in a string inside the host program. |
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831 To execute a chunk, |
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832 Lua first <em>loads</em> it, |
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833 precompiling the chunk's code into instructions for a virtual machine, |
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834 and then Lua executes the compiled code |
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835 with an interpreter for the virtual machine. |
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836 |
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837 |
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838 <p> |
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839 Chunks can also be precompiled into binary form; |
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840 see program <code>luac</code> and function <a href="#pdf-string.dump"><code>string.dump</code></a> for details. |
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841 Programs in source and compiled forms are interchangeable; |
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842 Lua automatically detects the file type and acts accordingly (see <a href="#pdf-load"><code>load</code></a>). |
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843 |
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844 |
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845 |
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846 |
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847 |
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848 <h3>3.3.3 – <a name="3.3.3">Assignment</a></h3> |
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849 |
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850 <p> |
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851 Lua allows multiple assignments. |
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852 Therefore, the syntax for assignment |
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853 defines a list of variables on the left side |
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854 and a list of expressions on the right side. |
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855 The elements in both lists are separated by commas: |
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856 |
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857 <pre> |
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858 stat ::= varlist ‘<b>=</b>’ explist |
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859 varlist ::= var {‘<b>,</b>’ var} |
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860 explist ::= exp {‘<b>,</b>’ exp} |
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861 </pre><p> |
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862 Expressions are discussed in <a href="#3.4">§3.4</a>. |
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863 |
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864 |
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865 <p> |
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866 Before the assignment, |
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867 the list of values is <em>adjusted</em> to the length of |
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868 the list of variables. |
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869 If there are more values than needed, |
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870 the excess values are thrown away. |
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871 If there are fewer values than needed, |
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872 the list is extended with as many <b>nil</b>'s as needed. |
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873 If the list of expressions ends with a function call, |
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874 then all values returned by that call enter the list of values, |
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875 before the adjustment |
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876 (except when the call is enclosed in parentheses; see <a href="#3.4">§3.4</a>). |
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877 |
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878 |
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879 <p> |
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880 The assignment statement first evaluates all its expressions |
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881 and only then the assignments are performed. |
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882 Thus the code |
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883 |
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884 <pre> |
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885 i = 3 |
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886 i, a[i] = i+1, 20 |
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887 </pre><p> |
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888 sets <code>a[3]</code> to 20, without affecting <code>a[4]</code> |
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889 because the <code>i</code> in <code>a[i]</code> is evaluated (to 3) |
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890 before it is assigned 4. |
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891 Similarly, the line |
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892 |
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893 <pre> |
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894 x, y = y, x |
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895 </pre><p> |
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896 exchanges the values of <code>x</code> and <code>y</code>, |
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897 and |
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898 |
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899 <pre> |
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900 x, y, z = y, z, x |
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901 </pre><p> |
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902 cyclically permutes the values of <code>x</code>, <code>y</code>, and <code>z</code>. |
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903 |
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904 |
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905 <p> |
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906 The meaning of assignments to global variables |
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907 and table fields can be changed via metatables. |
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908 An assignment to an indexed variable <code>t[i] = val</code> is equivalent to |
|
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909 <code>settable_event(t,i,val)</code>. |
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910 (See <a href="#2.4">§2.4</a> for a complete description of the |
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911 <code>settable_event</code> function. |
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912 This function is not defined or callable in Lua. |
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913 We use it here only for explanatory purposes.) |
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914 |
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915 |
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|
916 <p> |
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917 An assignment to a global name <code>x = val</code> |
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918 is equivalent to the assignment |
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919 <code>_ENV.x = val</code> (see <a href="#2.2">§2.2</a>). |
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920 |
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921 |
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922 |
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923 |
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924 |
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925 <h3>3.3.4 – <a name="3.3.4">Control Structures</a></h3><p> |
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926 The control structures |
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927 <b>if</b>, <b>while</b>, and <b>repeat</b> have the usual meaning and |
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928 familiar syntax: |
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|
929 |
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930 |
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931 |
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|
932 |
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933 <pre> |
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934 stat ::= <b>while</b> exp <b>do</b> block <b>end</b> |
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935 stat ::= <b>repeat</b> block <b>until</b> exp |
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936 stat ::= <b>if</b> exp <b>then</b> block {<b>elseif</b> exp <b>then</b> block} [<b>else</b> block] <b>end</b> |
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937 </pre><p> |
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938 Lua also has a <b>for</b> statement, in two flavors (see <a href="#3.3.5">§3.3.5</a>). |
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939 |
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940 |
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941 <p> |
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942 The condition expression of a |
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943 control structure can return any value. |
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944 Both <b>false</b> and <b>nil</b> are considered false. |
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945 All values different from <b>nil</b> and <b>false</b> are considered true |
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946 (in particular, the number 0 and the empty string are also true). |
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947 |
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948 |
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949 <p> |
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950 In the <b>repeat</b>–<b>until</b> loop, |
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951 the inner block does not end at the <b>until</b> keyword, |
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952 but only after the condition. |
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953 So, the condition can refer to local variables |
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954 declared inside the loop block. |
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955 |
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956 |
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957 <p> |
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958 The <b>goto</b> statement transfers the program control to a label. |
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959 For syntactical reasons, |
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960 labels in Lua are considered statements too: |
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961 |
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962 |
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963 |
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964 <pre> |
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965 stat ::= <b>goto</b> Name |
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966 stat ::= label |
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967 label ::= ‘<b>::</b>’ Name ‘<b>::</b>’ |
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968 </pre> |
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969 |
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970 <p> |
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971 A label is visible in the entire block where it is defined, |
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972 except |
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973 inside nested blocks where a label with the same name is defined and |
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974 inside nested functions. |
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975 A goto may jump to any visible label as long as it does not |
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976 enter into the scope of a local variable. |
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977 |
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|
978 |
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979 <p> |
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980 Labels and empty statements are called <em>void statements</em>, |
|
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|
981 as they perform no actions. |
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|
982 |
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|
983 |
|
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984 <p> |
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|
985 The <b>break</b> statement terminates the execution of a |
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|
986 <b>while</b>, <b>repeat</b>, or <b>for</b> loop, |
|
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|
987 skipping to the next statement after the loop: |
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988 |
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989 |
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990 <pre> |
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991 stat ::= <b>break</b> |
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992 </pre><p> |
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993 A <b>break</b> ends the innermost enclosing loop. |
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994 |
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995 |
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996 <p> |
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997 The <b>return</b> statement is used to return values |
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998 from a function or a chunk |
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999 (which is an anonymous function). |
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1000 |
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1001 Functions can return more than one value, |
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1002 so the syntax for the <b>return</b> statement is |
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1003 |
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1004 <pre> |
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1005 stat ::= <b>return</b> [explist] [‘<b>;</b>’] |
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1006 </pre> |
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1007 |
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1008 <p> |
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1009 The <b>return</b> statement can only be written |
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1010 as the last statement of a block. |
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1011 If it is really necessary to <b>return</b> in the middle of a block, |
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1012 then an explicit inner block can be used, |
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1013 as in the idiom <code>do return end</code>, |
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1014 because now <b>return</b> is the last statement in its (inner) block. |
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1015 |
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1016 |
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1017 |
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1018 |
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1019 |
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1020 <h3>3.3.5 – <a name="3.3.5">For Statement</a></h3> |
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1021 |
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1022 <p> |
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1023 |
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1024 The <b>for</b> statement has two forms: |
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1025 one numeric and one generic. |
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1026 |
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1027 |
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1028 <p> |
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1029 The numeric <b>for</b> loop repeats a block of code while a |
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1030 control variable runs through an arithmetic progression. |
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1031 It has the following syntax: |
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1032 |
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1033 <pre> |
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1034 stat ::= <b>for</b> Name ‘<b>=</b>’ exp ‘<b>,</b>’ exp [‘<b>,</b>’ exp] <b>do</b> block <b>end</b> |
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1035 </pre><p> |
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1036 The <em>block</em> is repeated for <em>name</em> starting at the value of |
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1037 the first <em>exp</em>, until it passes the second <em>exp</em> by steps of the |
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1038 third <em>exp</em>. |
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1039 More precisely, a <b>for</b> statement like |
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1040 |
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1041 <pre> |
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1042 for v = <em>e1</em>, <em>e2</em>, <em>e3</em> do <em>block</em> end |
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1043 </pre><p> |
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1044 is equivalent to the code: |
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1045 |
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1046 <pre> |
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1047 do |
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1048 local <em>var</em>, <em>limit</em>, <em>step</em> = tonumber(<em>e1</em>), tonumber(<em>e2</em>), tonumber(<em>e3</em>) |
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1049 if not (<em>var</em> and <em>limit</em> and <em>step</em>) then error() end |
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1050 <em>var</em> = <em>var</em> - <em>step</em> |
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1051 while true do |
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1052 <em>var</em> = <em>var</em> + <em>step</em> |
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1053 if (<em>step</em> >= 0 and <em>var</em> > <em>limit</em>) or (<em>step</em> < 0 and <em>var</em> < <em>limit</em>) then |
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1054 break |
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1055 end |
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1056 local v = <em>var</em> |
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1057 <em>block</em> |
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1058 end |
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1059 end |
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1060 </pre> |
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1061 |
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1062 <p> |
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1063 Note the following: |
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1064 |
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1065 <ul> |
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1066 |
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1067 <li> |
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1068 All three control expressions are evaluated only once, |
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1069 before the loop starts. |
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1070 They must all result in numbers. |
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1071 </li> |
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1072 |
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1073 <li> |
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1074 <code><em>var</em></code>, <code><em>limit</em></code>, and <code><em>step</em></code> are invisible variables. |
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1075 The names shown here are for explanatory purposes only. |
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1076 </li> |
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1077 |
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1078 <li> |
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1079 If the third expression (the step) is absent, |
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1080 then a step of 1 is used. |
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1081 </li> |
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1082 |
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1083 <li> |
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1084 You can use <b>break</b> and <b>goto</b> to exit a <b>for</b> loop. |
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1085 </li> |
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1086 |
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1087 <li> |
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1088 The loop variable <code>v</code> is local to the loop body. |
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1089 If you need its value after the loop, |
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1090 assign it to another variable before exiting the loop. |
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1091 </li> |
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1092 |
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1093 </ul> |
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1094 |
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1095 <p> |
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1096 The generic <b>for</b> statement works over functions, |
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1097 called <em>iterators</em>. |
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1098 On each iteration, the iterator function is called to produce a new value, |
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1099 stopping when this new value is <b>nil</b>. |
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1100 The generic <b>for</b> loop has the following syntax: |
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1101 |
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1102 <pre> |
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1103 stat ::= <b>for</b> namelist <b>in</b> explist <b>do</b> block <b>end</b> |
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1104 namelist ::= Name {‘<b>,</b>’ Name} |
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1105 </pre><p> |
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1106 A <b>for</b> statement like |
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1107 |
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1108 <pre> |
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1109 for <em>var_1</em>, ···, <em>var_n</em> in <em>explist</em> do <em>block</em> end |
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1110 </pre><p> |
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1111 is equivalent to the code: |
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1112 |
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1113 <pre> |
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1114 do |
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1115 local <em>f</em>, <em>s</em>, <em>var</em> = <em>explist</em> |
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1116 while true do |
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1117 local <em>var_1</em>, ···, <em>var_n</em> = <em>f</em>(<em>s</em>, <em>var</em>) |
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1118 if <em>var_1</em> == nil then break end |
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1119 <em>var</em> = <em>var_1</em> |
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1120 <em>block</em> |
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1121 end |
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1122 end |
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1123 </pre><p> |
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1124 Note the following: |
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1125 |
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1126 <ul> |
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1127 |
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1128 <li> |
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1129 <code><em>explist</em></code> is evaluated only once. |
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1130 Its results are an <em>iterator</em> function, |
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1131 a <em>state</em>, |
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1132 and an initial value for the first <em>iterator variable</em>. |
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1133 </li> |
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1134 |
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1135 <li> |
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1136 <code><em>f</em></code>, <code><em>s</em></code>, and <code><em>var</em></code> are invisible variables. |
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1137 The names are here for explanatory purposes only. |
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1138 </li> |
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1139 |
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1140 <li> |
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1141 You can use <b>break</b> to exit a <b>for</b> loop. |
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1142 </li> |
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1143 |
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1144 <li> |
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1145 The loop variables <code><em>var_i</em></code> are local to the loop; |
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1146 you cannot use their values after the <b>for</b> ends. |
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1147 If you need these values, |
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1148 then assign them to other variables before breaking or exiting the loop. |
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1149 </li> |
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1150 |
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1151 </ul> |
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1152 |
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1153 |
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1154 |
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1155 |
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1156 <h3>3.3.6 – <a name="3.3.6">Function Calls as Statements</a></h3><p> |
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1157 To allow possible side-effects, |
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1158 function calls can be executed as statements: |
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1159 |
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1160 <pre> |
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1161 stat ::= functioncall |
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1162 </pre><p> |
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1163 In this case, all returned values are thrown away. |
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1164 Function calls are explained in <a href="#3.4.10">§3.4.10</a>. |
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1165 |
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1166 |
|
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1167 |
|
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1168 |
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1169 |
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1170 <h3>3.3.7 – <a name="3.3.7">Local Declarations</a></h3><p> |
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1171 Local variables can be declared anywhere inside a block. |
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1172 The declaration can include an initial assignment: |
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1173 |
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1174 <pre> |
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1175 stat ::= <b>local</b> namelist [‘<b>=</b>’ explist] |
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1176 </pre><p> |
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1177 If present, an initial assignment has the same semantics |
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1178 of a multiple assignment (see <a href="#3.3.3">§3.3.3</a>). |
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1179 Otherwise, all variables are initialized with <b>nil</b>. |
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1180 |
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1181 |
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1182 <p> |
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1183 A chunk is also a block (see <a href="#3.3.2">§3.3.2</a>), |
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1184 and so local variables can be declared in a chunk outside any explicit block. |
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1185 |
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1186 |
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1187 <p> |
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1188 The visibility rules for local variables are explained in <a href="#3.5">§3.5</a>. |
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1189 |
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1190 |
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1191 |
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1192 |
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1193 |
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1194 |
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1195 |
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1196 <h2>3.4 – <a name="3.4">Expressions</a></h2> |
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1197 |
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1198 <p> |
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1199 The basic expressions in Lua are the following: |
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1200 |
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1201 <pre> |
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1202 exp ::= prefixexp |
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1203 exp ::= <b>nil</b> | <b>false</b> | <b>true</b> |
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1204 exp ::= Numeral |
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1205 exp ::= LiteralString |
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1206 exp ::= functiondef |
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1207 exp ::= tableconstructor |
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1208 exp ::= ‘<b>...</b>’ |
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1209 exp ::= exp binop exp |
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1210 exp ::= unop exp |
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1211 prefixexp ::= var | functioncall | ‘<b>(</b>’ exp ‘<b>)</b>’ |
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1212 </pre> |
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1213 |
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1214 <p> |
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1215 Numerals and literal strings are explained in <a href="#3.1">§3.1</a>; |
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1216 variables are explained in <a href="#3.2">§3.2</a>; |
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1217 function definitions are explained in <a href="#3.4.11">§3.4.11</a>; |
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1218 function calls are explained in <a href="#3.4.10">§3.4.10</a>; |
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1219 table constructors are explained in <a href="#3.4.9">§3.4.9</a>. |
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1220 Vararg expressions, |
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1221 denoted by three dots ('<code>...</code>'), can only be used when |
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1222 directly inside a vararg function; |
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1223 they are explained in <a href="#3.4.11">§3.4.11</a>. |
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1224 |
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1225 |
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1226 <p> |
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1227 Binary operators comprise arithmetic operators (see <a href="#3.4.1">§3.4.1</a>), |
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1228 bitwise operators (see <a href="#3.4.2">§3.4.2</a>), |
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1229 relational operators (see <a href="#3.4.4">§3.4.4</a>), logical operators (see <a href="#3.4.5">§3.4.5</a>), |
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1230 and the concatenation operator (see <a href="#3.4.6">§3.4.6</a>). |
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1231 Unary operators comprise the unary minus (see <a href="#3.4.1">§3.4.1</a>), |
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1232 the unary bitwise not (see <a href="#3.4.2">§3.4.2</a>), |
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1233 the unary logical <b>not</b> (see <a href="#3.4.5">§3.4.5</a>), |
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1234 and the unary <em>length operator</em> (see <a href="#3.4.7">§3.4.7</a>). |
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1235 |
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1236 |
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1237 <p> |
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1238 Both function calls and vararg expressions can result in multiple values. |
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1239 If a function call is used as a statement (see <a href="#3.3.6">§3.3.6</a>), |
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1240 then its return list is adjusted to zero elements, |
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1241 thus discarding all returned values. |
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1242 If an expression is used as the last (or the only) element |
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1243 of a list of expressions, |
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1244 then no adjustment is made |
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1245 (unless the expression is enclosed in parentheses). |
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1246 In all other contexts, |
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1247 Lua adjusts the result list to one element, |
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1248 either discarding all values except the first one |
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1249 or adding a single <b>nil</b> if there are no values. |
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1250 |
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1251 |
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1252 <p> |
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1253 Here are some examples: |
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1254 |
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1255 <pre> |
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1256 f() -- adjusted to 0 results |
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1257 g(f(), x) -- f() is adjusted to 1 result |
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1258 g(x, f()) -- g gets x plus all results from f() |
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1259 a,b,c = f(), x -- f() is adjusted to 1 result (c gets nil) |
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1260 a,b = ... -- a gets the first vararg parameter, b gets |
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1261 -- the second (both a and b can get nil if there |
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1262 -- is no corresponding vararg parameter) |
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1263 |
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1264 a,b,c = x, f() -- f() is adjusted to 2 results |
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1265 a,b,c = f() -- f() is adjusted to 3 results |
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1266 return f() -- returns all results from f() |
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1267 return ... -- returns all received vararg parameters |
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1268 return x,y,f() -- returns x, y, and all results from f() |
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1269 {f()} -- creates a list with all results from f() |
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1270 {...} -- creates a list with all vararg parameters |
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1271 {f(), nil} -- f() is adjusted to 1 result |
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1272 </pre> |
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1273 |
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1274 <p> |
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1275 Any expression enclosed in parentheses always results in only one value. |
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1276 Thus, |
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1277 <code>(f(x,y,z))</code> is always a single value, |
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1278 even if <code>f</code> returns several values. |
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1279 (The value of <code>(f(x,y,z))</code> is the first value returned by <code>f</code> |
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1280 or <b>nil</b> if <code>f</code> does not return any values.) |
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1281 |
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1282 |
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1283 |
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1284 <h3>3.4.1 – <a name="3.4.1">Arithmetic Operators</a></h3><p> |
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1285 Lua supports the following arithmetic operators: |
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1286 |
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1287 <ul> |
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1288 <li><b><code>+</code>: </b>addition</li> |
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1289 <li><b><code>-</code>: </b>subtraction</li> |
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1290 <li><b><code>*</code>: </b>multiplication</li> |
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1291 <li><b><code>/</code>: </b>float division</li> |
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1292 <li><b><code>//</code>: </b>floor division</li> |
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1293 <li><b><code>%</code>: </b>modulo</li> |
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1294 <li><b><code>^</code>: </b>exponentiation</li> |
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1295 <li><b><code>-</code>: </b>unary minus</li> |
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1296 </ul> |
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1297 |
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1298 <p> |
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1299 With the exception of exponentiation and float division, |
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1300 the arithmetic operators work as follows: |
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1301 If both operands are integers, |
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1302 the operation is performed over integers and the result is an integer. |
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1303 Otherwise, if both operands are numbers |
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1304 or strings that can be converted to |
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1305 numbers (see <a href="#3.4.3">§3.4.3</a>), |
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1306 then they are converted to floats, |
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1307 the operation is performed following the usual rules |
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1308 for floating-point arithmetic |
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1309 (usually the IEEE 754 standard), |
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1310 and the result is a float. |
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1311 |
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1312 |
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1313 <p> |
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1314 Exponentiation and float division (<code>/</code>) |
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1315 always convert their operands to floats |
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1316 and the result is always a float. |
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1317 Exponentiation uses the ISO C function <code>pow</code>, |
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1318 so that it works for non-integer exponents too. |
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1319 |
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1320 |
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1321 <p> |
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1322 Floor division (<code>//</code>) is a division |
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1323 that rounds the quotient towards minus infinite, |
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1324 that is, the floor of the division of its operands. |
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1325 |
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1326 |
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1327 <p> |
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1328 Modulo is defined as the remainder of a division |
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1329 that rounds the quotient towards minus infinite (floor division). |
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1330 |
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1331 |
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1332 <p> |
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1333 In case of overflows in integer arithmetic, |
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1334 all operations <em>wrap around</em>, |
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1335 according to the usual rules of two-complement arithmetic. |
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1336 (In other words, |
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1337 they return the unique representable integer |
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1338 that is equal modulo <em>2<sup>64</sup></em> to the mathematical result.) |
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1339 |
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1340 |
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1341 |
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1342 <h3>3.4.2 – <a name="3.4.2">Bitwise Operators</a></h3><p> |
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1343 Lua supports the following bitwise operators: |
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1344 |
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1345 <ul> |
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1346 <li><b><code>&</code>: </b>bitwise and</li> |
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1347 <li><b><code>|</code>: </b>bitwise or</li> |
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1348 <li><b><code>~</code>: </b>bitwise exclusive or</li> |
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1349 <li><b><code>>></code>: </b>right shift</li> |
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1350 <li><b><code><<</code>: </b>left shift</li> |
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1351 <li><b><code>~</code>: </b>unary bitwise not</li> |
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1352 </ul> |
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1353 |
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1354 <p> |
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1355 All bitwise operations convert its operands to integers |
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1356 (see <a href="#3.4.3">§3.4.3</a>), |
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1357 operate on all bits of those integers, |
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1358 and result in an integer. |
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1359 |
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1360 |
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1361 <p> |
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1362 Both right and left shifts fill the vacant bits with zeros. |
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1363 Negative displacements shift to the other direction; |
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1364 displacements with absolute values equal to or higher than |
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1365 the number of bits in an integer |
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1366 result in zero (as all bits are shifted out). |
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1367 |
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1368 |
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1369 |
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1370 |
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1371 |
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1372 <h3>3.4.3 – <a name="3.4.3">Coercions and Conversions</a></h3><p> |
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1373 Lua provides some automatic conversions between some |
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1374 types and representations at run time. |
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1375 Bitwise operators always convert float operands to integers. |
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1376 Exponentiation and float division |
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1377 always convert integer operands to floats. |
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1378 All other arithmetic operations applied to mixed numbers |
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1379 (integers and floats) convert the integer operand to a float; |
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1380 this is called the <em>usual rule</em>. |
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1381 The C API also converts both integers to floats and |
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1382 floats to integers, as needed. |
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1383 Moreover, string concatenation accepts numbers as arguments, |
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1384 besides strings. |
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1385 |
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1386 |
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1387 <p> |
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1388 Lua also converts strings to numbers, |
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1389 whenever a number is expected. |
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1390 |
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1391 |
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1392 <p> |
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1393 In a conversion from integer to float, |
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1394 if the integer value has an exact representation as a float, |
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1395 that is the result. |
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1396 Otherwise, |
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1397 the conversion gets the nearest higher or |
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1398 the nearest lower representable value. |
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1399 This kind of conversion never fails. |
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1400 |
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1401 |
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1402 <p> |
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1403 The conversion from float to integer |
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1404 checks whether the float has an exact representation as an integer |
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1405 (that is, the float has an integral value and |
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1406 it is in the range of integer representation). |
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1407 If it does, that representation is the result. |
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1408 Otherwise, the conversion fails. |
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1409 |
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1410 |
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1411 <p> |
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1412 The conversion from strings to numbers goes as follows: |
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1413 First, the string is converted to an integer or a float, |
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1414 following its syntax and the rules of the Lua lexer. |
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1415 (The string may have also leading and trailing spaces and a sign.) |
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1416 Then, the resulting number is converted to the required type |
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1417 (float or integer) according to the previous rules. |
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1418 |
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1419 |
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1420 <p> |
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1421 The conversion from numbers to strings uses a |
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1422 non-specified human-readable format. |
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1423 For complete control over how numbers are converted to strings, |
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1424 use the <code>format</code> function from the string library |
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1425 (see <a href="#pdf-string.format"><code>string.format</code></a>). |
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1426 |
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1427 |
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1428 |
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1429 |
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1430 |
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1431 <h3>3.4.4 – <a name="3.4.4">Relational Operators</a></h3><p> |
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1432 Lua supports the following relational operators: |
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1433 |
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1434 <ul> |
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1435 <li><b><code>==</code>: </b>equality</li> |
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1436 <li><b><code>~=</code>: </b>inequality</li> |
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1437 <li><b><code><</code>: </b>less than</li> |
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1438 <li><b><code>></code>: </b>greater than</li> |
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1439 <li><b><code><=</code>: </b>less or equal</li> |
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1440 <li><b><code>>=</code>: </b>greater or equal</li> |
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1441 </ul><p> |
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1442 These operators always result in <b>false</b> or <b>true</b>. |
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1443 |
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1444 |
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1445 <p> |
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1446 Equality (<code>==</code>) first compares the type of its operands. |
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1447 If the types are different, then the result is <b>false</b>. |
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1448 Otherwise, the values of the operands are compared. |
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1449 Strings are compared in the obvious way. |
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1450 Numbers follow the usual rule for binary operations: |
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1451 if both operands are integers, |
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1452 they are compared as integers; |
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1453 otherwise, they are converted to floats |
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1454 and compared as such. |
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1455 |
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1456 |
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1457 <p> |
|
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1458 Tables, userdata, and threads |
|
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1459 are compared by reference: |
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1460 two objects are considered equal only if they are the same object. |
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1461 Every time you create a new object |
|
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1462 (a table, userdata, or thread), |
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1463 this new object is different from any previously existing object. |
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1464 Closures with the same reference are always equal. |
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1465 Closures with any detectable difference |
|
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1466 (different behavior, different definition) are always different. |
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1467 |
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1468 |
|
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1469 <p> |
|
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1470 You can change the way that Lua compares tables and userdata |
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1471 by using the "eq" metamethod (see <a href="#2.4">§2.4</a>). |
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1472 |
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1473 |
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1474 <p> |
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1475 Equality comparisons do not convert strings to numbers |
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1476 or vice versa. |
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1477 Thus, <code>"0"==0</code> evaluates to <b>false</b>, |
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1478 and <code>t[0]</code> and <code>t["0"]</code> denote different |
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1479 entries in a table. |
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1480 |
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1481 |
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1482 <p> |
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1483 The operator <code>~=</code> is exactly the negation of equality (<code>==</code>). |
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1484 |
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1485 |
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1486 <p> |
|
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1487 The order operators work as follows. |
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1488 If both arguments are numbers, |
|
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1489 then they are compared following |
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1490 the usual rule for binary operations. |
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1491 Otherwise, if both arguments are strings, |
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1492 then their values are compared according to the current locale. |
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1493 Otherwise, Lua tries to call the "lt" or the "le" |
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1494 metamethod (see <a href="#2.4">§2.4</a>). |
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1495 A comparison <code>a > b</code> is translated to <code>b < a</code> |
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1496 and <code>a >= b</code> is translated to <code>b <= a</code>. |
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1497 |
|
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1498 |
|
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1499 |
|
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|
1500 |
|
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|
1501 |
|
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1502 <h3>3.4.5 – <a name="3.4.5">Logical Operators</a></h3><p> |
|
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1503 The logical operators in Lua are |
|
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1504 <b>and</b>, <b>or</b>, and <b>not</b>. |
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1505 Like the control structures (see <a href="#3.3.4">§3.3.4</a>), |
|
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1506 all logical operators consider both <b>false</b> and <b>nil</b> as false |
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1507 and anything else as true. |
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1508 |
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1509 |
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1510 <p> |
|
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1511 The negation operator <b>not</b> always returns <b>false</b> or <b>true</b>. |
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1512 The conjunction operator <b>and</b> returns its first argument |
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1513 if this value is <b>false</b> or <b>nil</b>; |
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1514 otherwise, <b>and</b> returns its second argument. |
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1515 The disjunction operator <b>or</b> returns its first argument |
|
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1516 if this value is different from <b>nil</b> and <b>false</b>; |
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1517 otherwise, <b>or</b> returns its second argument. |
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1518 Both <b>and</b> and <b>or</b> use short-circuit evaluation; |
|
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1519 that is, |
|
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1520 the second operand is evaluated only if necessary. |
|
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1521 Here are some examples: |
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1522 |
|
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1523 <pre> |
|
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1524 10 or 20 --> 10 |
|
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|
1525 10 or error() --> 10 |
|
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1526 nil or "a" --> "a" |
|
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1527 nil and 10 --> nil |
|
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1528 false and error() --> false |
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|
1529 false and nil --> false |
|
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1530 false or nil --> nil |
|
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1531 10 and 20 --> 20 |
|
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|
1532 </pre><p> |
|
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|
1533 (In this manual, |
|
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|
1534 <code>--></code> indicates the result of the preceding expression.) |
|
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1535 |
|
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|
1536 |
|
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|
1537 |
|
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|
1538 |
|
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|
1539 |
|
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1540 <h3>3.4.6 – <a name="3.4.6">Concatenation</a></h3><p> |
|
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1541 The string concatenation operator in Lua is |
|
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1542 denoted by two dots ('<code>..</code>'). |
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1543 If both operands are strings or numbers, then they are converted to |
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1544 strings according to the rules described in <a href="#3.4.3">§3.4.3</a>. |
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1545 Otherwise, the <code>__concat</code> metamethod is called (see <a href="#2.4">§2.4</a>). |
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1546 |
|
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1547 |
|
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|
1548 |
|
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|
1549 |
|
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1550 |
|
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|
1551 <h3>3.4.7 – <a name="3.4.7">The Length Operator</a></h3> |
|
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1552 |
|
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1553 <p> |
|
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1554 The length operator is denoted by the unary prefix operator <code>#</code>. |
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1555 The length of a string is its number of bytes |
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1556 (that is, the usual meaning of string length when each |
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1557 character is one byte). |
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1558 |
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1559 |
|
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1560 <p> |
|
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1561 A program can modify the behavior of the length operator for |
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1562 any value but strings through the <code>__len</code> metamethod (see <a href="#2.4">§2.4</a>). |
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1563 |
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1564 |
|
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1565 <p> |
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1566 Unless a <code>__len</code> metamethod is given, |
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1567 the length of a table <code>t</code> is only defined if the |
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1568 table is a <em>sequence</em>, |
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1569 that is, |
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1570 the set of its positive numeric keys is equal to <em>{1..n}</em> |
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1571 for some non-negative integer <em>n</em>. |
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1572 In that case, <em>n</em> is its length. |
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1573 Note that a table like |
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1574 |
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1575 <pre> |
|
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1576 {10, 20, nil, 40} |
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1577 </pre><p> |
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1578 is not a sequence, because it has the key <code>4</code> |
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1579 but does not have the key <code>3</code>. |
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1580 (So, there is no <em>n</em> such that the set <em>{1..n}</em> is equal |
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1581 to the set of positive numeric keys of that table.) |
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1582 Note, however, that non-numeric keys do not interfere |
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1583 with whether a table is a sequence. |
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1584 |
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1585 |
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1586 |
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1587 |
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1588 |
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1589 <h3>3.4.8 – <a name="3.4.8">Precedence</a></h3><p> |
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1590 Operator precedence in Lua follows the table below, |
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1591 from lower to higher priority: |
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1592 |
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1593 <pre> |
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1594 or |
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1595 and |
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1596 < > <= >= ~= == |
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1597 | |
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1598 ~ |
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1599 & |
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1600 << >> |
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1601 .. |
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1602 + - |
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1603 * / // % |
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1604 unary operators (not # - ~) |
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1605 ^ |
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1606 </pre><p> |
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1607 As usual, |
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1608 you can use parentheses to change the precedences of an expression. |
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1609 The concatenation ('<code>..</code>') and exponentiation ('<code>^</code>') |
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1610 operators are right associative. |
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1611 All other binary operators are left associative. |
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1612 |
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1613 |
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1614 |
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1615 |
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1616 |
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1617 <h3>3.4.9 – <a name="3.4.9">Table Constructors</a></h3><p> |
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1618 Table constructors are expressions that create tables. |
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1619 Every time a constructor is evaluated, a new table is created. |
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1620 A constructor can be used to create an empty table |
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1621 or to create a table and initialize some of its fields. |
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1622 The general syntax for constructors is |
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1623 |
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1624 <pre> |
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1625 tableconstructor ::= ‘<b>{</b>’ [fieldlist] ‘<b>}</b>’ |
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1626 fieldlist ::= field {fieldsep field} [fieldsep] |
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1627 field ::= ‘<b>[</b>’ exp ‘<b>]</b>’ ‘<b>=</b>’ exp | Name ‘<b>=</b>’ exp | exp |
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1628 fieldsep ::= ‘<b>,</b>’ | ‘<b>;</b>’ |
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1629 </pre> |
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1630 |
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1631 <p> |
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1632 Each field of the form <code>[exp1] = exp2</code> adds to the new table an entry |
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1633 with key <code>exp1</code> and value <code>exp2</code>. |
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1634 A field of the form <code>name = exp</code> is equivalent to |
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1635 <code>["name"] = exp</code>. |
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1636 Finally, fields of the form <code>exp</code> are equivalent to |
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1637 <code>[i] = exp</code>, where <code>i</code> are consecutive integers |
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1638 starting with 1. |
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1639 Fields in the other formats do not affect this counting. |
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1640 For example, |
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1641 |
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1642 <pre> |
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1643 a = { [f(1)] = g; "x", "y"; x = 1, f(x), [30] = 23; 45 } |
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1644 </pre><p> |
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1645 is equivalent to |
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1646 |
|
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1647 <pre> |
|
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1648 do |
|
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1649 local t = {} |
|
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1650 t[f(1)] = g |
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1651 t[1] = "x" -- 1st exp |
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1652 t[2] = "y" -- 2nd exp |
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1653 t.x = 1 -- t["x"] = 1 |
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1654 t[3] = f(x) -- 3rd exp |
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1655 t[30] = 23 |
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1656 t[4] = 45 -- 4th exp |
|
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1657 a = t |
|
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1658 end |
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1659 </pre> |
|
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1660 |
|
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1661 <p> |
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1662 The order of the assignments in a constructor is undefined. |
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1663 (This order would be relevant only when there are repeated keys.) |
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1664 |
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1665 |
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1666 <p> |
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1667 If the last field in the list has the form <code>exp</code> |
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1668 and the expression is a function call or a vararg expression, |
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1669 then all values returned by this expression enter the list consecutively |
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1670 (see <a href="#3.4.10">§3.4.10</a>). |
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1671 |
|
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1672 |
|
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1673 <p> |
|
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1674 The field list can have an optional trailing separator, |
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1675 as a convenience for machine-generated code. |
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1676 |
|
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1677 |
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1678 |
|
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1679 |
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1680 |
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1681 <h3>3.4.10 – <a name="3.4.10">Function Calls</a></h3><p> |
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1682 A function call in Lua has the following syntax: |
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1683 |
|
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1684 <pre> |
|
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1685 functioncall ::= prefixexp args |
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1686 </pre><p> |
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1687 In a function call, |
|
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1688 first prefixexp and args are evaluated. |
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1689 If the value of prefixexp has type <em>function</em>, |
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1690 then this function is called |
|
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1691 with the given arguments. |
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1692 Otherwise, the prefixexp "call" metamethod is called, |
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1693 having as first parameter the value of prefixexp, |
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1694 followed by the original call arguments |
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1695 (see <a href="#2.4">§2.4</a>). |
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1696 |
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1697 |
|
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1698 <p> |
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1699 The form |
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1700 |
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1701 <pre> |
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1702 functioncall ::= prefixexp ‘<b>:</b>’ Name args |
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1703 </pre><p> |
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1704 can be used to call "methods". |
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1705 A call <code>v:name(<em>args</em>)</code> |
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1706 is syntactic sugar for <code>v.name(v,<em>args</em>)</code>, |
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1707 except that <code>v</code> is evaluated only once. |
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1708 |
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1709 |
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1710 <p> |
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1711 Arguments have the following syntax: |
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1712 |
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1713 <pre> |
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1714 args ::= ‘<b>(</b>’ [explist] ‘<b>)</b>’ |
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1715 args ::= tableconstructor |
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1716 args ::= LiteralString |
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1717 </pre><p> |
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1718 All argument expressions are evaluated before the call. |
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1719 A call of the form <code>f{<em>fields</em>}</code> is |
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1720 syntactic sugar for <code>f({<em>fields</em>})</code>; |
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1721 that is, the argument list is a single new table. |
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1722 A call of the form <code>f'<em>string</em>'</code> |
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1723 (or <code>f"<em>string</em>"</code> or <code>f[[<em>string</em>]]</code>) |
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1724 is syntactic sugar for <code>f('<em>string</em>')</code>; |
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1725 that is, the argument list is a single literal string. |
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1726 |
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1727 |
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1728 <p> |
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1729 A call of the form <code>return <em>functioncall</em></code> is called |
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1730 a <em>tail call</em>. |
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1731 Lua implements <em>proper tail calls</em> |
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1732 (or <em>proper tail recursion</em>): |
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1733 in a tail call, |
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1734 the called function reuses the stack entry of the calling function. |
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1735 Therefore, there is no limit on the number of nested tail calls that |
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1736 a program can execute. |
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1737 However, a tail call erases any debug information about the |
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1738 calling function. |
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1739 Note that a tail call only happens with a particular syntax, |
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1740 where the <b>return</b> has one single function call as argument; |
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1741 this syntax makes the calling function return exactly |
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1742 the returns of the called function. |
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1743 So, none of the following examples are tail calls: |
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1744 |
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1745 <pre> |
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1746 return (f(x)) -- results adjusted to 1 |
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1747 return 2 * f(x) |
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1748 return x, f(x) -- additional results |
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1749 f(x); return -- results discarded |
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1750 return x or f(x) -- results adjusted to 1 |
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|
1751 </pre> |
|
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1752 |
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1753 |
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1754 |
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1755 |
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1756 <h3>3.4.11 – <a name="3.4.11">Function Definitions</a></h3> |
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1757 |
|
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1758 <p> |
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1759 The syntax for function definition is |
|
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|
1760 |
|
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|
1761 <pre> |
|
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1762 functiondef ::= <b>function</b> funcbody |
|
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1763 funcbody ::= ‘<b>(</b>’ [parlist] ‘<b>)</b>’ block <b>end</b> |
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1764 </pre> |
|
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|
1765 |
|
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|
1766 <p> |
|
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1767 The following syntactic sugar simplifies function definitions: |
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1768 |
|
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1769 <pre> |
|
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1770 stat ::= <b>function</b> funcname funcbody |
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1771 stat ::= <b>local</b> <b>function</b> Name funcbody |
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1772 funcname ::= Name {‘<b>.</b>’ Name} [‘<b>:</b>’ Name] |
|
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1773 </pre><p> |
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|
1774 The statement |
|
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|
1775 |
|
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|
1776 <pre> |
|
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1777 function f () <em>body</em> end |
|
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1778 </pre><p> |
|
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1779 translates to |
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|
1780 |
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|
1781 <pre> |
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1782 f = function () <em>body</em> end |
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1783 </pre><p> |
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|
1784 The statement |
|
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|
1785 |
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|
1786 <pre> |
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1787 function t.a.b.c.f () <em>body</em> end |
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1788 </pre><p> |
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1789 translates to |
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|
1790 |
|
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|
1791 <pre> |
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1792 t.a.b.c.f = function () <em>body</em> end |
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1793 </pre><p> |
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1794 The statement |
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|
1795 |
|
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1796 <pre> |
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1797 local function f () <em>body</em> end |
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1798 </pre><p> |
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1799 translates to |
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|
1800 |
|
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|
1801 <pre> |
|
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1802 local f; f = function () <em>body</em> end |
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1803 </pre><p> |
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1804 not to |
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1805 |
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|
1806 <pre> |
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1807 local f = function () <em>body</em> end |
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1808 </pre><p> |
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1809 (This only makes a difference when the body of the function |
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1810 contains references to <code>f</code>.) |
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1811 |
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1812 |
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1813 <p> |
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1814 A function definition is an executable expression, |
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1815 whose value has type <em>function</em>. |
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1816 When Lua precompiles a chunk, |
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1817 all its function bodies are precompiled too. |
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1818 Then, whenever Lua executes the function definition, |
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1819 the function is <em>instantiated</em> (or <em>closed</em>). |
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1820 This function instance (or <em>closure</em>) |
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1821 is the final value of the expression. |
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1822 |
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1823 |
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1824 <p> |
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1825 Parameters act as local variables that are |
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1826 initialized with the argument values: |
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1827 |
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1828 <pre> |
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1829 parlist ::= namelist [‘<b>,</b>’ ‘<b>...</b>’] | ‘<b>...</b>’ |
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1830 </pre><p> |
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1831 When a function is called, |
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1832 the list of arguments is adjusted to |
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1833 the length of the list of parameters, |
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1834 unless the function is a <em>vararg function</em>, |
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1835 which is indicated by three dots ('<code>...</code>') |
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1836 at the end of its parameter list. |
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1837 A vararg function does not adjust its argument list; |
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1838 instead, it collects all extra arguments and supplies them |
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1839 to the function through a <em>vararg expression</em>, |
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1840 which is also written as three dots. |
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1841 The value of this expression is a list of all actual extra arguments, |
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1842 similar to a function with multiple results. |
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1843 If a vararg expression is used inside another expression |
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1844 or in the middle of a list of expressions, |
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1845 then its return list is adjusted to one element. |
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1846 If the expression is used as the last element of a list of expressions, |
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1847 then no adjustment is made |
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1848 (unless that last expression is enclosed in parentheses). |
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1849 |
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1850 |
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1851 <p> |
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1852 As an example, consider the following definitions: |
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1853 |
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1854 <pre> |
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1855 function f(a, b) end |
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1856 function g(a, b, ...) end |
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1857 function r() return 1,2,3 end |
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1858 </pre><p> |
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1859 Then, we have the following mapping from arguments to parameters and |
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1860 to the vararg expression: |
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1861 |
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1862 <pre> |
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1863 CALL PARAMETERS |
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1864 |
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1865 f(3) a=3, b=nil |
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1866 f(3, 4) a=3, b=4 |
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1867 f(3, 4, 5) a=3, b=4 |
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1868 f(r(), 10) a=1, b=10 |
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1869 f(r()) a=1, b=2 |
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1870 |
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1871 g(3) a=3, b=nil, ... --> (nothing) |
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1872 g(3, 4) a=3, b=4, ... --> (nothing) |
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1873 g(3, 4, 5, 8) a=3, b=4, ... --> 5 8 |
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1874 g(5, r()) a=5, b=1, ... --> 2 3 |
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1875 </pre> |
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1876 |
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1877 <p> |
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1878 Results are returned using the <b>return</b> statement (see <a href="#3.3.4">§3.3.4</a>). |
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1879 If control reaches the end of a function |
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1880 without encountering a <b>return</b> statement, |
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1881 then the function returns with no results. |
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1882 |
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1883 |
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1884 <p> |
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1885 |
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1886 There is a system-dependent limit on the number of values |
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1887 that a function may return. |
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1888 This limit is guaranteed to be larger than 1000. |
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1889 |
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1890 |
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1891 <p> |
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1892 The <em>colon</em> syntax |
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1893 is used for defining <em>methods</em>, |
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1894 that is, functions that have an implicit extra parameter <code>self</code>. |
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1895 Thus, the statement |
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1896 |
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1897 <pre> |
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1898 function t.a.b.c:f (<em>params</em>) <em>body</em> end |
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1899 </pre><p> |
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1900 is syntactic sugar for |
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1901 |
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1902 <pre> |
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1903 t.a.b.c.f = function (self, <em>params</em>) <em>body</em> end |
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1904 </pre> |
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1905 |
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1906 |
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1907 |
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1908 |
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1909 |
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1910 |
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1911 <h2>3.5 – <a name="3.5">Visibility Rules</a></h2> |
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1912 |
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1913 <p> |
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1914 |
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1915 Lua is a lexically scoped language. |
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1916 The scope of a local variable begins at the first statement after |
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1917 its declaration and lasts until the last non-void statement |
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1918 of the innermost block that includes the declaration. |
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1919 Consider the following example: |
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1920 |
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1921 <pre> |
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1922 x = 10 -- global variable |
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1923 do -- new block |
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1924 local x = x -- new 'x', with value 10 |
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1925 print(x) --> 10 |
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1926 x = x+1 |
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1927 do -- another block |
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1928 local x = x+1 -- another 'x' |
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1929 print(x) --> 12 |
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1930 end |
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1931 print(x) --> 11 |
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1932 end |
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1933 print(x) --> 10 (the global one) |
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1934 </pre> |
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1935 |
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1936 <p> |
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1937 Notice that, in a declaration like <code>local x = x</code>, |
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1938 the new <code>x</code> being declared is not in scope yet, |
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1939 and so the second <code>x</code> refers to the outside variable. |
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1940 |
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1941 |
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1942 <p> |
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1943 Because of the lexical scoping rules, |
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1944 local variables can be freely accessed by functions |
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1945 defined inside their scope. |
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1946 A local variable used by an inner function is called |
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1947 an <em>upvalue</em>, or <em>external local variable</em>, |
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1948 inside the inner function. |
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1949 |
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1950 |
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1951 <p> |
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1952 Notice that each execution of a <b>local</b> statement |
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1953 defines new local variables. |
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1954 Consider the following example: |
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1955 |
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1956 <pre> |
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1957 a = {} |
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1958 local x = 20 |
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1959 for i=1,10 do |
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1960 local y = 0 |
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1961 a[i] = function () y=y+1; return x+y end |
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1962 end |
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1963 </pre><p> |
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1964 The loop creates ten closures |
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1965 (that is, ten instances of the anonymous function). |
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1966 Each of these closures uses a different <code>y</code> variable, |
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1967 while all of them share the same <code>x</code>. |
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1968 |
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1969 |
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1970 |
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1971 |
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1972 |
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1973 <h1>4 – <a name="4">The Application Program Interface</a></h1> |
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1974 |
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1975 <p> |
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1976 |
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1977 This section describes the C API for Lua, that is, |
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1978 the set of C functions available to the host program to communicate |
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1979 with Lua. |
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1980 All API functions and related types and constants |
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1981 are declared in the header file <a name="pdf-lua.h"><code>lua.h</code></a>. |
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1982 |
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1983 |
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1984 <p> |
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1985 Even when we use the term "function", |
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1986 any facility in the API may be provided as a macro instead. |
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1987 Except where stated otherwise, |
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1988 all such macros use each of their arguments exactly once |
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1989 (except for the first argument, which is always a Lua state), |
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1990 and so do not generate any hidden side-effects. |
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1991 |
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1992 |
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1993 <p> |
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1994 As in most C libraries, |
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1995 the Lua API functions do not check their arguments for validity or consistency. |
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1996 However, you can change this behavior by compiling Lua |
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1997 with the macro <a name="pdf-LUA_USE_APICHECK"><code>LUA_USE_APICHECK</code></a> defined. |
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1998 |
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1999 |
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2000 |
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2001 <h2>4.1 – <a name="4.1">The Stack</a></h2> |
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2002 |
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2003 <p> |
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2004 Lua uses a <em>virtual stack</em> to pass values to and from C. |
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2005 Each element in this stack represents a Lua value |
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2006 (<b>nil</b>, number, string, etc.). |
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2007 |
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2008 |
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2009 <p> |
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2010 Whenever Lua calls C, the called function gets a new stack, |
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2011 which is independent of previous stacks and of stacks of |
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2012 C functions that are still active. |
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2013 This stack initially contains any arguments to the C function |
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2014 and it is where the C function pushes its results |
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2015 to be returned to the caller (see <a href="#lua_CFunction"><code>lua_CFunction</code></a>). |
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2016 |
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2017 |
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2018 <p> |
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2019 For convenience, |
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2020 most query operations in the API do not follow a strict stack discipline. |
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2021 Instead, they can refer to any element in the stack |
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2022 by using an <em>index</em>: |
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2023 A positive index represents an absolute stack position |
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2024 (starting at 1); |
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2025 a negative index represents an offset relative to the top of the stack. |
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2026 More specifically, if the stack has <em>n</em> elements, |
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2027 then index 1 represents the first element |
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2028 (that is, the element that was pushed onto the stack first) |
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2029 and |
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2030 index <em>n</em> represents the last element; |
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2031 index -1 also represents the last element |
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2032 (that is, the element at the top) |
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2033 and index <em>-n</em> represents the first element. |
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2034 |
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2035 |
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2036 |
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2037 |
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2038 |
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2039 <h2>4.2 – <a name="4.2">Stack Size</a></h2> |
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2040 |
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2041 <p> |
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2042 When you interact with the Lua API, |
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2043 you are responsible for ensuring consistency. |
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2044 In particular, |
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2045 <em>you are responsible for controlling stack overflow</em>. |
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2046 You can use the function <a href="#lua_checkstack"><code>lua_checkstack</code></a> |
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2047 to ensure that the stack has enough space for pushing new elements. |
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2048 |
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2049 |
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2050 <p> |
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2051 Whenever Lua calls C, |
|
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2052 it ensures that the stack has space for |
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2053 at least <a name="pdf-LUA_MINSTACK"><code>LUA_MINSTACK</code></a> extra slots. |
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2054 <code>LUA_MINSTACK</code> is defined as 20, |
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2055 so that usually you do not have to worry about stack space |
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2056 unless your code has loops pushing elements onto the stack. |
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2057 |
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2058 |
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2059 <p> |
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2060 When you call a Lua function |
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2061 without a fixed number of results (see <a href="#lua_call"><code>lua_call</code></a>), |
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2062 Lua ensures that the stack has enough space for all results, |
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2063 but it does not ensure any extra space. |
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2064 So, before pushing anything in the stack after such a call |
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2065 you should use <a href="#lua_checkstack"><code>lua_checkstack</code></a>. |
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2066 |
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2067 |
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2068 |
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2069 |
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2070 |
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2071 <h2>4.3 – <a name="4.3">Valid and Acceptable Indices</a></h2> |
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2072 |
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2073 <p> |
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2074 Any function in the API that receives stack indices |
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2075 works only with <em>valid indices</em> or <em>acceptable indices</em>. |
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2076 |
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2077 |
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2078 <p> |
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2079 A <em>valid index</em> is an index that refers to a |
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2080 real position within the stack, that is, |
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2081 its position lies between 1 and the stack top |
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2082 (<code>1 ≤ abs(index) ≤ top</code>). |
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2083 |
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2084 Usually, functions that can modify the value at an index |
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2085 require valid indices. |
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2086 |
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2087 |
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2088 <p> |
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2089 Unless otherwise noted, |
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2090 any function that accepts valid indices also accepts <em>pseudo-indices</em>, |
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2091 which represent some Lua values that are accessible to C code |
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2092 but which are not in the stack. |
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2093 Pseudo-indices are used to access the registry |
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2094 and the upvalues of a C function (see <a href="#4.4">§4.4</a>). |
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2095 |
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2096 |
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2097 <p> |
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2098 Functions that do not need a specific stack position, |
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2099 but only a value in the stack (e.g., query functions), |
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2100 can be called with acceptable indices. |
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2101 An <em>acceptable index</em> can be any valid index, |
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2102 including the pseudo-indices, |
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2103 but it also can be any positive index after the stack top |
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2104 within the space allocated for the stack, |
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2105 that is, indices up to the stack size. |
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2106 (Note that 0 is never an acceptable index.) |
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2107 Except when noted otherwise, |
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2108 functions in the API work with acceptable indices. |
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2109 |
|
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2110 |
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2111 <p> |
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2112 Acceptable indices serve to avoid extra tests |
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2113 against the stack top when querying the stack. |
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2114 For instance, a C function can query its third argument |
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2115 without the need to first check whether there is a third argument, |
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2116 that is, without the need to check whether 3 is a valid index. |
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2117 |
|
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2118 |
|
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2119 <p> |
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2120 For functions that can be called with acceptable indices, |
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2121 any non-valid index is treated as if it |
|
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2122 contains a value of a virtual type <a name="pdf-LUA_TNONE"><code>LUA_TNONE</code></a>, |
|
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2123 which behaves like a nil value. |
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2124 |
|
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2125 |
|
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2126 |
|
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|
2127 |
|
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|
2128 |
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2129 <h2>4.4 – <a name="4.4">C Closures</a></h2> |
|
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2130 |
|
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2131 <p> |
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2132 When a C function is created, |
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2133 it is possible to associate some values with it, |
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2134 thus creating a <em>C closure</em> |
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2135 (see <a href="#lua_pushcclosure"><code>lua_pushcclosure</code></a>); |
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2136 these values are called <em>upvalues</em> and are |
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2137 accessible to the function whenever it is called. |
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2138 |
|
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2139 |
|
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2140 <p> |
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2141 Whenever a C function is called, |
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2142 its upvalues are located at specific pseudo-indices. |
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2143 These pseudo-indices are produced by the macro |
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2144 <a href="#lua_upvalueindex"><code>lua_upvalueindex</code></a>. |
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2145 The first value associated with a function is at position |
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2146 <code>lua_upvalueindex(1)</code>, and so on. |
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2147 Any access to <code>lua_upvalueindex(<em>n</em>)</code>, |
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2148 where <em>n</em> is greater than the number of upvalues of the |
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2149 current function (but not greater than 256), |
|
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2150 produces an acceptable but invalid index. |
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2151 |
|
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2152 |
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2153 |
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2154 |
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2155 |
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2156 <h2>4.5 – <a name="4.5">Registry</a></h2> |
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2157 |
|
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2158 <p> |
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2159 Lua provides a <em>registry</em>, |
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2160 a predefined table that can be used by any C code to |
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2161 store whatever Lua values it needs to store. |
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2162 The registry table is always located at pseudo-index |
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2163 <a name="pdf-LUA_REGISTRYINDEX"><code>LUA_REGISTRYINDEX</code></a>, |
|
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2164 which is a valid index. |
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2165 Any C library can store data into this table, |
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2166 but it must take care to choose keys |
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2167 that are different from those used |
|
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2168 by other libraries, to avoid collisions. |
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2169 Typically, you should use as key a string containing your library name, |
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2170 or a light userdata with the address of a C object in your code, |
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2171 or any Lua object created by your code. |
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2172 As with variable names, |
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2173 string keys starting with an underscore followed by |
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2174 uppercase letters are reserved for Lua. |
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2175 |
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2176 |
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2177 <p> |
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2178 The integer keys in the registry are used |
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2179 by the reference mechanism (see <a href="#luaL_ref"><code>luaL_ref</code></a>) |
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2180 and by some predefined values. |
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2181 Therefore, integer keys must not be used for other purposes. |
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2182 |
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2183 |
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2184 <p> |
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2185 When you create a new Lua state, |
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2186 its registry comes with some predefined values. |
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2187 These predefined values are indexed with integer keys |
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2188 defined as constants in <code>lua.h</code>. |
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2189 The following constants are defined: |
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2190 |
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2191 <ul> |
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2192 <li><b><a name="pdf-LUA_RIDX_MAINTHREAD"><code>LUA_RIDX_MAINTHREAD</code></a>: </b> At this index the registry has |
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2193 the main thread of the state. |
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2194 (The main thread is the one created together with the state.) |
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2195 </li> |
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2196 |
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2197 <li><b><a name="pdf-LUA_RIDX_GLOBALS"><code>LUA_RIDX_GLOBALS</code></a>: </b> At this index the registry has |
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2198 the global environment. |
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2199 </li> |
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2200 </ul> |
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2201 |
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2202 |
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2203 |
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2204 |
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2205 <h2>4.6 – <a name="4.6">Error Handling in C</a></h2> |
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2206 |
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2207 <p> |
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2208 Internally, Lua uses the C <code>longjmp</code> facility to handle errors. |
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2209 (Lua will use exceptions if you compile it as C++; |
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2210 search for <code>LUAI_THROW</code> in the source code for details.) |
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2211 When Lua faces any error |
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2212 (such as a memory allocation error, type errors, syntax errors, |
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2213 and runtime errors) |
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2214 it <em>raises</em> an error; |
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2215 that is, it does a long jump. |
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2216 A <em>protected environment</em> uses <code>setjmp</code> |
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2217 to set a recovery point; |
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2218 any error jumps to the most recent active recovery point. |
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2219 |
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2220 |
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2221 <p> |
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2222 If an error happens outside any protected environment, |
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2223 Lua calls a <em>panic function</em> (see <a href="#lua_atpanic"><code>lua_atpanic</code></a>) |
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2224 and then calls <code>abort</code>, |
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2225 thus exiting the host application. |
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2226 Your panic function can avoid this exit by |
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2227 never returning |
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2228 (e.g., doing a long jump to your own recovery point outside Lua). |
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2229 |
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2230 |
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2231 <p> |
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2232 The panic function runs as if it were a message handler (see <a href="#2.3">§2.3</a>); |
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2233 in particular, the error message is at the top of the stack. |
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2234 However, there is no guarantee about stack space. |
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2235 To push anything on the stack, |
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2236 the panic function must first check the available space (see <a href="#4.2">§4.2</a>). |
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2237 |
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2238 |
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2239 <p> |
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2240 Most functions in the API can raise an error, |
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2241 for instance due to a memory allocation error. |
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2242 The documentation for each function indicates whether |
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2243 it can raise errors. |
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2244 |
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2245 |
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2246 <p> |
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2247 Inside a C function you can raise an error by calling <a href="#lua_error"><code>lua_error</code></a>. |
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2248 |
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2249 |
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2250 |
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2251 |
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2252 |
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2253 <h2>4.7 – <a name="4.7">Handling Yields in C</a></h2> |
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2254 |
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2255 <p> |
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2256 Internally, Lua uses the C <code>longjmp</code> facility to yield a coroutine. |
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2257 Therefore, if a C function <code>foo</code> calls an API function |
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2258 and this API function yields |
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2259 (directly or indirectly by calling another function that yields), |
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2260 Lua cannot return to <code>foo</code> any more, |
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2261 because the <code>longjmp</code> removes its frame from the C stack. |
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2262 |
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2263 |
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2264 <p> |
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2265 To avoid this kind of problem, |
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2266 Lua raises an error whenever it tries to yield across an API call, |
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2267 except for three functions: |
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2268 <a href="#lua_yieldk"><code>lua_yieldk</code></a>, <a href="#lua_callk"><code>lua_callk</code></a>, and <a href="#lua_pcallk"><code>lua_pcallk</code></a>. |
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2269 All those functions receive a <em>continuation function</em> |
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2270 (as a parameter named <code>k</code>) to continue execution after a yield. |
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2271 |
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2272 |
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2273 <p> |
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2274 We need to set some terminology to explain continuations. |
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2275 We have a C function called from Lua which we will call |
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2276 the <em>original function</em>. |
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2277 This original function then calls one of those three functions in the C API, |
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2278 which we will call the <em>callee function</em>, |
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2279 that then yields the current thread. |
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2280 (This can happen when the callee function is <a href="#lua_yieldk"><code>lua_yieldk</code></a>, |
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2281 or when the callee function is either <a href="#lua_callk"><code>lua_callk</code></a> or <a href="#lua_pcallk"><code>lua_pcallk</code></a> |
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2282 and the function called by them yields.) |
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2283 |
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2284 |
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2285 <p> |
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2286 Suppose the running thread yields while executing the callee function. |
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2287 After the thread resumes, |
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2288 it eventually will finish running the callee function. |
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2289 However, |
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2290 the callee function cannot return to the original function, |
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2291 because its frame in the C stack was destroyed by the yield. |
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2292 Instead, Lua calls a <em>continuation function</em>, |
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2293 which was given as an argument to the callee function. |
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2294 As the name implies, |
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2295 the continuation function should continue the task |
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2296 of the original function. |
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2297 |
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2298 |
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2299 <p> |
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2300 As an illustration, consider the following function: |
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2301 |
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2302 <pre> |
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2303 int original_function (lua_State *L) { |
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2304 ... /* code 1 */ |
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2305 status = lua_pcall(L, n, m, h); /* calls Lua */ |
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2306 ... /* code 2 */ |
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2307 } |
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2308 </pre><p> |
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2309 Now we want to allow |
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2310 the Lua code being run by <a href="#lua_pcall"><code>lua_pcall</code></a> to yield. |
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2311 First, we can rewrite our function like here: |
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2312 |
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2313 <pre> |
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2314 int k (lua_State *L, int status, lua_KContext ctx) { |
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2315 ... /* code 2 */ |
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2316 } |
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2317 |
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2318 int original_function (lua_State *L) { |
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2319 ... /* code 1 */ |
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2320 return k(L, lua_pcall(L, n, m, h), ctx); |
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2321 } |
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2322 </pre><p> |
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2323 In the above code, |
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2324 the new function <code>k</code> is a |
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2325 <em>continuation function</em> (with type <a href="#lua_KFunction"><code>lua_KFunction</code></a>), |
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2326 which should do all the work that the original function |
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2327 was doing after calling <a href="#lua_pcall"><code>lua_pcall</code></a>. |
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2328 Now, we must inform Lua that it must call <code>k</code> if the Lua code |
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2329 being executed by <a href="#lua_pcall"><code>lua_pcall</code></a> gets interrupted in some way |
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2330 (errors or yielding), |
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2331 so we rewrite the code as here, |
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2332 replacing <a href="#lua_pcall"><code>lua_pcall</code></a> by <a href="#lua_pcallk"><code>lua_pcallk</code></a>: |
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2333 |
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2334 <pre> |
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2335 int original_function (lua_State *L) { |
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2336 ... /* code 1 */ |
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2337 return k(L, lua_pcallk(L, n, m, h, ctx2, k), ctx1); |
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2338 } |
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2339 </pre><p> |
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2340 Note the external, explicit call to the continuation: |
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2341 Lua will call the continuation only if needed, that is, |
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2342 in case of errors or resuming after a yield. |
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2343 If the called function returns normally without ever yielding, |
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2344 <a href="#lua_pcallk"><code>lua_pcallk</code></a> (and <a href="#lua_callk"><code>lua_callk</code></a>) will also return normally. |
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2345 (Of course, instead of calling the continuation in that case, |
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2346 you can do the equivalent work directly inside the original function.) |
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2347 |
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2348 |
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2349 <p> |
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2350 Besides the Lua state, |
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2351 the continuation function has two other parameters: |
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2352 the final status of the call plus the context value (<code>ctx</code>) that |
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2353 was passed originally to <a href="#lua_pcallk"><code>lua_pcallk</code></a>. |
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2354 (Lua does not use this context value; |
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2355 it only passes this value from the original function to the |
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2356 continuation function.) |
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2357 For <a href="#lua_pcallk"><code>lua_pcallk</code></a>, |
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2358 the status is the same value that would be returned by <a href="#lua_pcallk"><code>lua_pcallk</code></a>, |
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2359 except that it is <a href="#pdf-LUA_YIELD"><code>LUA_YIELD</code></a> when being executed after a yield |
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2360 (instead of <a href="#pdf-LUA_OK"><code>LUA_OK</code></a>). |
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2361 For <a href="#lua_yieldk"><code>lua_yieldk</code></a> and <a href="#lua_callk"><code>lua_callk</code></a>, |
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2362 the status is always <a href="#pdf-LUA_YIELD"><code>LUA_YIELD</code></a> when Lua calls the continuation. |
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2363 (For these two functions, |
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2364 Lua will not call the continuation in case of errors, |
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2365 because they do not handle errors.) |
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2366 Similarly, when using <a href="#lua_callk"><code>lua_callk</code></a>, |
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2367 you should call the continuation function |
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2368 with <a href="#pdf-LUA_OK"><code>LUA_OK</code></a> as the status. |
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2369 (For <a href="#lua_yieldk"><code>lua_yieldk</code></a>, there is not much point in calling |
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2370 directly the continuation function, |
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2371 because <a href="#lua_yieldk"><code>lua_yieldk</code></a> usually does not return.) |
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2372 |
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2373 |
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2374 <p> |
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2375 Lua treats the continuation function as if it were the original function. |
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2376 The continuation function receives the same Lua stack |
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2377 from the original function, |
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2378 in the same state it would be if the callee function had returned. |
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2379 (For instance, |
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2380 after a <a href="#lua_callk"><code>lua_callk</code></a> the function and its arguments are |
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2381 removed from the stack and replaced by the results from the call.) |
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2382 It also has the same upvalues. |
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2383 Whatever it returns is handled by Lua as if it were the return |
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2384 of the original function. |
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2385 |
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2386 |
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2387 |
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2388 |
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2389 |
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2390 <h2>4.8 – <a name="4.8">Functions and Types</a></h2> |
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2391 |
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2392 <p> |
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2393 Here we list all functions and types from the C API in |
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2394 alphabetical order. |
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2395 Each function has an indicator like this: |
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2396 <span class="apii">[-o, +p, <em>x</em>]</span> |
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2397 |
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2398 |
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2399 <p> |
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2400 The first field, <code>o</code>, |
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2401 is how many elements the function pops from the stack. |
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2402 The second field, <code>p</code>, |
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2403 is how many elements the function pushes onto the stack. |
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2404 (Any function always pushes its results after popping its arguments.) |
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2405 A field in the form <code>x|y</code> means the function can push (or pop) |
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2406 <code>x</code> or <code>y</code> elements, |
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2407 depending on the situation; |
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2408 an interrogation mark '<code>?</code>' means that |
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2409 we cannot know how many elements the function pops/pushes |
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2410 by looking only at its arguments |
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2411 (e.g., they may depend on what is on the stack). |
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2412 The third field, <code>x</code>, |
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2413 tells whether the function may raise errors: |
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2414 '<code>-</code>' means the function never raises any error; |
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2415 '<code>e</code>' means the function may raise errors; |
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2416 '<code>v</code>' means the function may raise an error on purpose. |
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2417 |
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2418 |
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2419 |
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2420 <hr><h3><a name="lua_absindex"><code>lua_absindex</code></a></h3><p> |
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2421 <span class="apii">[-0, +0, –]</span> |
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2422 <pre>int lua_absindex (lua_State *L, int idx);</pre> |
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2423 |
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2424 <p> |
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2425 Converts the acceptable index <code>idx</code> into an absolute index |
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2426 (that is, one that does not depend on the stack top). |
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2427 |
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2428 |
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2429 |
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2430 |
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2431 |
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2432 <hr><h3><a name="lua_Alloc"><code>lua_Alloc</code></a></h3> |
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2433 <pre>typedef void * (*lua_Alloc) (void *ud, |
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2434 void *ptr, |
|
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2435 size_t osize, |
|
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|
2436 size_t nsize);</pre> |
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2437 |
|
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2438 <p> |
|
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|
2439 The type of the memory-allocation function used by Lua states. |
|
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2440 The allocator function must provide a |
|
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|
2441 functionality similar to <code>realloc</code>, |
|
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2442 but not exactly the same. |
|
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|
2443 Its arguments are |
|
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|
2444 <code>ud</code>, an opaque pointer passed to <a href="#lua_newstate"><code>lua_newstate</code></a>; |
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|
2445 <code>ptr</code>, a pointer to the block being allocated/reallocated/freed; |
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2446 <code>osize</code>, the original size of the block or some code about what |
|
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2447 is being allocated; |
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2448 and <code>nsize</code>, the new size of the block. |
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2449 |
|
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2450 |
|
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|
2451 <p> |
|
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|
2452 When <code>ptr</code> is not <code>NULL</code>, |
|
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|
2453 <code>osize</code> is the size of the block pointed by <code>ptr</code>, |
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|
2454 that is, the size given when it was allocated or reallocated. |
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2455 |
|
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|
2456 |
|
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|
2457 <p> |
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|
2458 When <code>ptr</code> is <code>NULL</code>, |
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|
2459 <code>osize</code> encodes the kind of object that Lua is allocating. |
|
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2460 <code>osize</code> is any of |
|
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|
2461 <a href="#pdf-LUA_TSTRING"><code>LUA_TSTRING</code></a>, <a href="#pdf-LUA_TTABLE"><code>LUA_TTABLE</code></a>, <a href="#pdf-LUA_TFUNCTION"><code>LUA_TFUNCTION</code></a>, |
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|
2462 <a href="#pdf-LUA_TUSERDATA"><code>LUA_TUSERDATA</code></a>, or <a href="#pdf-LUA_TTHREAD"><code>LUA_TTHREAD</code></a> when (and only when) |
|
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|
2463 Lua is creating a new object of that type. |
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2464 When <code>osize</code> is some other value, |
|
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|
2465 Lua is allocating memory for something else. |
|
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2466 |
|
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2467 |
|
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|
2468 <p> |
|
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|
2469 Lua assumes the following behavior from the allocator function: |
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2470 |
|
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|
2471 |
|
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2472 <p> |
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2473 When <code>nsize</code> is zero, |
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|
2474 the allocator must behave like <code>free</code> |
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2475 and return <code>NULL</code>. |
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2476 |
|
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2477 |
|
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2478 <p> |
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|
2479 When <code>nsize</code> is not zero, |
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|
2480 the allocator must behave like <code>realloc</code>. |
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2481 The allocator returns <code>NULL</code> |
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|
2482 if and only if it cannot fulfill the request. |
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2483 Lua assumes that the allocator never fails when |
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2484 <code>osize >= nsize</code>. |
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2485 |
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2486 |
|
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2487 <p> |
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2488 Here is a simple implementation for the allocator function. |
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2489 It is used in the auxiliary library by <a href="#luaL_newstate"><code>luaL_newstate</code></a>. |
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2490 |
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2491 <pre> |
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2492 static void *l_alloc (void *ud, void *ptr, size_t osize, |
|
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2493 size_t nsize) { |
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2494 (void)ud; (void)osize; /* not used */ |
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2495 if (nsize == 0) { |
|
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2496 free(ptr); |
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2497 return NULL; |
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2498 } |
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2499 else |
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2500 return realloc(ptr, nsize); |
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2501 } |
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2502 </pre><p> |
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2503 Note that Standard C ensures |
|
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2504 that <code>free(NULL)</code> has no effect and that |
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2505 <code>realloc(NULL,size)</code> is equivalent to <code>malloc(size)</code>. |
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2506 This code assumes that <code>realloc</code> does not fail when shrinking a block. |
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2507 (Although Standard C does not ensure this behavior, |
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2508 it seems to be a safe assumption.) |
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2509 |
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2510 |
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2511 |
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2512 |
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2513 |
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2514 <hr><h3><a name="lua_arith"><code>lua_arith</code></a></h3><p> |
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2515 <span class="apii">[-(2|1), +1, <em>e</em>]</span> |
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2516 <pre>void lua_arith (lua_State *L, int op);</pre> |
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2517 |
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2518 <p> |
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2519 Performs an arithmetic or bitwise operation over the two values |
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2520 (or one, in the case of negations) |
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2521 at the top of the stack, |
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2522 with the value at the top being the second operand, |
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2523 pops these values, and pushes the result of the operation. |
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2524 The function follows the semantics of the corresponding Lua operator |
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2525 (that is, it may call metamethods). |
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2526 |
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2527 |
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2528 <p> |
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2529 The value of <code>op</code> must be one of the following constants: |
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2530 |
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2531 <ul> |
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2532 |
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2533 <li><b><a name="pdf-LUA_OPADD"><code>LUA_OPADD</code></a>: </b> performs addition (<code>+</code>)</li> |
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2534 <li><b><a name="pdf-LUA_OPSUB"><code>LUA_OPSUB</code></a>: </b> performs subtraction (<code>-</code>)</li> |
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2535 <li><b><a name="pdf-LUA_OPMUL"><code>LUA_OPMUL</code></a>: </b> performs multiplication (<code>*</code>)</li> |
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2536 <li><b><a name="pdf-LUA_OPDIV"><code>LUA_OPDIV</code></a>: </b> performs float division (<code>/</code>)</li> |
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2537 <li><b><a name="pdf-LUA_OPIDIV"><code>LUA_OPIDIV</code></a>: </b> performs floor division (<code>//</code>)</li> |
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2538 <li><b><a name="pdf-LUA_OPMOD"><code>LUA_OPMOD</code></a>: </b> performs modulo (<code>%</code>)</li> |
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2539 <li><b><a name="pdf-LUA_OPPOW"><code>LUA_OPPOW</code></a>: </b> performs exponentiation (<code>^</code>)</li> |
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2540 <li><b><a name="pdf-LUA_OPUNM"><code>LUA_OPUNM</code></a>: </b> performs mathematical negation (unary <code>-</code>)</li> |
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2541 <li><b><a name="pdf-LUA_OPBNOT"><code>LUA_OPBNOT</code></a>: </b> performs bitwise negation (<code>~</code>)</li> |
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2542 <li><b><a name="pdf-LUA_OPBAND"><code>LUA_OPBAND</code></a>: </b> performs bitwise and (<code>&</code>)</li> |
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2543 <li><b><a name="pdf-LUA_OPBOR"><code>LUA_OPBOR</code></a>: </b> performs bitwise or (<code>|</code>)</li> |
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2544 <li><b><a name="pdf-LUA_OPBXOR"><code>LUA_OPBXOR</code></a>: </b> performs bitwise exclusive or (<code>~</code>)</li> |
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2545 <li><b><a name="pdf-LUA_OPSHL"><code>LUA_OPSHL</code></a>: </b> performs left shift (<code><<</code>)</li> |
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2546 <li><b><a name="pdf-LUA_OPSHR"><code>LUA_OPSHR</code></a>: </b> performs right shift (<code>>></code>)</li> |
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2547 |
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2548 </ul> |
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2549 |
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2550 |
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2551 |
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2552 |
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2553 <hr><h3><a name="lua_atpanic"><code>lua_atpanic</code></a></h3><p> |
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2554 <span class="apii">[-0, +0, –]</span> |
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2555 <pre>lua_CFunction lua_atpanic (lua_State *L, lua_CFunction panicf);</pre> |
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2556 |
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2557 <p> |
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2558 Sets a new panic function and returns the old one (see <a href="#4.6">§4.6</a>). |
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2559 |
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2560 |
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2561 |
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2562 |
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2563 |
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2564 <hr><h3><a name="lua_call"><code>lua_call</code></a></h3><p> |
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2565 <span class="apii">[-(nargs+1), +nresults, <em>e</em>]</span> |
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2566 <pre>void lua_call (lua_State *L, int nargs, int nresults);</pre> |
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2567 |
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2568 <p> |
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2569 Calls a function. |
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2570 |
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2571 |
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2572 <p> |
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|
2573 To call a function you must use the following protocol: |
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2574 first, the function to be called is pushed onto the stack; |
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2575 then, the arguments to the function are pushed |
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2576 in direct order; |
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2577 that is, the first argument is pushed first. |
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2578 Finally you call <a href="#lua_call"><code>lua_call</code></a>; |
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2579 <code>nargs</code> is the number of arguments that you pushed onto the stack. |
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2580 All arguments and the function value are popped from the stack |
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2581 when the function is called. |
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2582 The function results are pushed onto the stack when the function returns. |
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2583 The number of results is adjusted to <code>nresults</code>, |
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2584 unless <code>nresults</code> is <a name="pdf-LUA_MULTRET"><code>LUA_MULTRET</code></a>. |
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2585 In this case, all results from the function are pushed. |
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2586 Lua takes care that the returned values fit into the stack space. |
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2587 The function results are pushed onto the stack in direct order |
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2588 (the first result is pushed first), |
|
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2589 so that after the call the last result is on the top of the stack. |
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2590 |
|
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2591 |
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2592 <p> |
|
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2593 Any error inside the called function is propagated upwards |
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2594 (with a <code>longjmp</code>). |
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2595 |
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2596 |
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2597 <p> |
|
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2598 The following example shows how the host program can do the |
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2599 equivalent to this Lua code: |
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2600 |
|
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2601 <pre> |
|
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2602 a = f("how", t.x, 14) |
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2603 </pre><p> |
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2604 Here it is in C: |
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2605 |
|
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2606 <pre> |
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2607 lua_getglobal(L, "f"); /* function to be called */ |
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2608 lua_pushliteral(L, "how"); /* 1st argument */ |
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2609 lua_getglobal(L, "t"); /* table to be indexed */ |
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2610 lua_getfield(L, -1, "x"); /* push result of t.x (2nd arg) */ |
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2611 lua_remove(L, -2); /* remove 't' from the stack */ |
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2612 lua_pushinteger(L, 14); /* 3rd argument */ |
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2613 lua_call(L, 3, 1); /* call 'f' with 3 arguments and 1 result */ |
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2614 lua_setglobal(L, "a"); /* set global 'a' */ |
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2615 </pre><p> |
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2616 Note that the code above is <em>balanced</em>: |
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2617 at its end, the stack is back to its original configuration. |
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2618 This is considered good programming practice. |
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2619 |
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2620 |
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2621 |
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2622 |
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2623 |
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2624 <hr><h3><a name="lua_callk"><code>lua_callk</code></a></h3><p> |
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2625 <span class="apii">[-(nargs + 1), +nresults, <em>e</em>]</span> |
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2626 <pre>void lua_callk (lua_State *L, |
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2627 int nargs, |
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2628 int nresults, |
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2629 lua_KContext ctx, |
|
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2630 lua_KFunction k);</pre> |
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2631 |
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2632 <p> |
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2633 This function behaves exactly like <a href="#lua_call"><code>lua_call</code></a>, |
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2634 but allows the called function to yield (see <a href="#4.7">§4.7</a>). |
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2635 |
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2636 |
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2637 |
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2638 |
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2639 |
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2640 <hr><h3><a name="lua_CFunction"><code>lua_CFunction</code></a></h3> |
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2641 <pre>typedef int (*lua_CFunction) (lua_State *L);</pre> |
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2642 |
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2643 <p> |
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2644 Type for C functions. |
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2645 |
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2646 |
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2647 <p> |
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2648 In order to communicate properly with Lua, |
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2649 a C function must use the following protocol, |
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2650 which defines the way parameters and results are passed: |
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2651 a C function receives its arguments from Lua in its stack |
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2652 in direct order (the first argument is pushed first). |
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2653 So, when the function starts, |
|
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|
2654 <code>lua_gettop(L)</code> returns the number of arguments received by the function. |
|
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2655 The first argument (if any) is at index 1 |
|
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2656 and its last argument is at index <code>lua_gettop(L)</code>. |
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2657 To return values to Lua, a C function just pushes them onto the stack, |
|
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2658 in direct order (the first result is pushed first), |
|
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2659 and returns the number of results. |
|
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2660 Any other value in the stack below the results will be properly |
|
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2661 discarded by Lua. |
|
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2662 Like a Lua function, a C function called by Lua can also return |
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2663 many results. |
|
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2664 |
|
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2665 |
|
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2666 <p> |
|
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2667 As an example, the following function receives a variable number |
|
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2668 of numerical arguments and returns their average and their sum: |
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2669 |
|
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|
2670 <pre> |
|
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2671 static int foo (lua_State *L) { |
|
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2672 int n = lua_gettop(L); /* number of arguments */ |
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2673 lua_Number sum = 0.0; |
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2674 int i; |
|
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|
2675 for (i = 1; i <= n; i++) { |
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|
2676 if (!lua_isnumber(L, i)) { |
|
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|
2677 lua_pushliteral(L, "incorrect argument"); |
|
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2678 lua_error(L); |
|
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2679 } |
|
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2680 sum += lua_tonumber(L, i); |
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2681 } |
|
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2682 lua_pushnumber(L, sum/n); /* first result */ |
|
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2683 lua_pushnumber(L, sum); /* second result */ |
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2684 return 2; /* number of results */ |
|
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2685 } |
|
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|
2686 </pre> |
|
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|
2687 |
|
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|
2688 |
|
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|
2689 |
|
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|
2690 |
|
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|
2691 <hr><h3><a name="lua_checkstack"><code>lua_checkstack</code></a></h3><p> |
|
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2692 <span class="apii">[-0, +0, –]</span> |
|
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|
2693 <pre>int lua_checkstack (lua_State *L, int n);</pre> |
|
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2694 |
|
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|
2695 <p> |
|
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|
2696 Ensures that the stack has space for at least <code>n</code> extra slots. |
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2697 It returns false if it cannot fulfill the request, |
|
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|
2698 either because it would cause the stack |
|
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2699 to be larger than a fixed maximum size |
|
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2700 (typically at least several thousand elements) or |
|
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2701 because it cannot allocate memory for the extra space. |
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2702 This function never shrinks the stack; |
|
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2703 if the stack is already larger than the new size, |
|
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2704 it is left unchanged. |
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2705 |
|
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2706 |
|
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2707 |
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2708 |
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2709 |
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2710 <hr><h3><a name="lua_close"><code>lua_close</code></a></h3><p> |
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2711 <span class="apii">[-0, +0, –]</span> |
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2712 <pre>void lua_close (lua_State *L);</pre> |
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2713 |
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2714 <p> |
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2715 Destroys all objects in the given Lua state |
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2716 (calling the corresponding garbage-collection metamethods, if any) |
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2717 and frees all dynamic memory used by this state. |
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2718 On several platforms, you may not need to call this function, |
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2719 because all resources are naturally released when the host program ends. |
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2720 On the other hand, long-running programs that create multiple states, |
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2721 such as daemons or web servers, |
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2722 will probably need to close states as soon as they are not needed. |
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2723 |
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2724 |
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2725 |
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2726 |
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2727 |
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2728 <hr><h3><a name="lua_compare"><code>lua_compare</code></a></h3><p> |
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2729 <span class="apii">[-0, +0, <em>e</em>]</span> |
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2730 <pre>int lua_compare (lua_State *L, int index1, int index2, int op);</pre> |
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2731 |
|
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2732 <p> |
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|
2733 Compares two Lua values. |
|
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2734 Returns 1 if the value at index <code>index1</code> satisfies <code>op</code> |
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2735 when compared with the value at index <code>index2</code>, |
|
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2736 following the semantics of the corresponding Lua operator |
|
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2737 (that is, it may call metamethods). |
|
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|
2738 Otherwise returns 0. |
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2739 Also returns 0 if any of the indices is not valid. |
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2740 |
|
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2741 |
|
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2742 <p> |
|
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2743 The value of <code>op</code> must be one of the following constants: |
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2744 |
|
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2745 <ul> |
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2746 |
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2747 <li><b><a name="pdf-LUA_OPEQ"><code>LUA_OPEQ</code></a>: </b> compares for equality (<code>==</code>)</li> |
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2748 <li><b><a name="pdf-LUA_OPLT"><code>LUA_OPLT</code></a>: </b> compares for less than (<code><</code>)</li> |
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2749 <li><b><a name="pdf-LUA_OPLE"><code>LUA_OPLE</code></a>: </b> compares for less or equal (<code><=</code>)</li> |
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2750 |
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2751 </ul> |
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2752 |
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2753 |
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2754 |
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2755 |
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2756 <hr><h3><a name="lua_concat"><code>lua_concat</code></a></h3><p> |
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2757 <span class="apii">[-n, +1, <em>e</em>]</span> |
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2758 <pre>void lua_concat (lua_State *L, int n);</pre> |
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2759 |
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2760 <p> |
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2761 Concatenates the <code>n</code> values at the top of the stack, |
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2762 pops them, and leaves the result at the top. |
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2763 If <code>n</code> is 1, the result is the single value on the stack |
|
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2764 (that is, the function does nothing); |
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2765 if <code>n</code> is 0, the result is the empty string. |
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2766 Concatenation is performed following the usual semantics of Lua |
|
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2767 (see <a href="#3.4.6">§3.4.6</a>). |
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2768 |
|
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|
2769 |
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2770 |
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2771 |
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2772 |
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2773 <hr><h3><a name="lua_copy"><code>lua_copy</code></a></h3><p> |
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2774 <span class="apii">[-0, +0, –]</span> |
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2775 <pre>void lua_copy (lua_State *L, int fromidx, int toidx);</pre> |
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2776 |
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2777 <p> |
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2778 Copies the element at index <code>fromidx</code> |
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2779 into the valid index <code>toidx</code>, |
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2780 replacing the value at that position. |
|
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2781 Values at other positions are not affected. |
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2782 |
|
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2783 |
|
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|
2784 |
|
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|
2785 |
|
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|
2786 |
|
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|
2787 <hr><h3><a name="lua_createtable"><code>lua_createtable</code></a></h3><p> |
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2788 <span class="apii">[-0, +1, <em>e</em>]</span> |
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|
2789 <pre>void lua_createtable (lua_State *L, int narr, int nrec);</pre> |
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2790 |
|
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|
2791 <p> |
|
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2792 Creates a new empty table and pushes it onto the stack. |
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2793 Parameter <code>narr</code> is a hint for how many elements the table |
|
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|
2794 will have as a sequence; |
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|
2795 parameter <code>nrec</code> is a hint for how many other elements |
|
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|
2796 the table will have. |
|
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|
2797 Lua may use these hints to preallocate memory for the new table. |
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2798 This pre-allocation is useful for performance when you know in advance |
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2799 how many elements the table will have. |
|
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|
2800 Otherwise you can use the function <a href="#lua_newtable"><code>lua_newtable</code></a>. |
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2801 |
|
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2802 |
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2803 |
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2804 |
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2805 |
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|
2806 <hr><h3><a name="lua_dump"><code>lua_dump</code></a></h3><p> |
|
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2807 <span class="apii">[-0, +0, <em>e</em>]</span> |
|
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2808 <pre>int lua_dump (lua_State *L, |
|
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|
2809 lua_Writer writer, |
|
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|
2810 void *data, |
|
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|
2811 int strip);</pre> |
|
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2812 |
|
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|
2813 <p> |
|
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|
2814 Dumps a function as a binary chunk. |
|
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2815 Receives a Lua function on the top of the stack |
|
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2816 and produces a binary chunk that, |
|
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|
2817 if loaded again, |
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2818 results in a function equivalent to the one dumped. |
|
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2819 As it produces parts of the chunk, |
|
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|
2820 <a href="#lua_dump"><code>lua_dump</code></a> calls function <code>writer</code> (see <a href="#lua_Writer"><code>lua_Writer</code></a>) |
|
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2821 with the given <code>data</code> |
|
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2822 to write them. |
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|
2823 |
|
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2824 |
|
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2825 <p> |
|
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2826 If <code>strip</code> is true, |
|
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2827 the binary representation is created without debug information |
|
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2828 about the function. |
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|
2829 |
|
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|
2830 |
|
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2831 <p> |
|
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2832 The value returned is the error code returned by the last |
|
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2833 call to the writer; |
|
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2834 0 means no errors. |
|
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2835 |
|
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2836 |
|
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2837 <p> |
|
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2838 This function does not pop the Lua function from the stack. |
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2839 |
|
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2840 |
|
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2841 |
|
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2842 |
|
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2843 |
|
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2844 <hr><h3><a name="lua_error"><code>lua_error</code></a></h3><p> |
|
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2845 <span class="apii">[-1, +0, <em>v</em>]</span> |
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2846 <pre>int lua_error (lua_State *L);</pre> |
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2847 |
|
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2848 <p> |
|
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|
2849 Generates a Lua error, |
|
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2850 using the value at the top of the stack as the error object. |
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2851 This function does a long jump, |
|
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2852 and therefore never returns |
|
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|
2853 (see <a href="#luaL_error"><code>luaL_error</code></a>). |
|
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|
2854 |
|
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diff
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|
2855 |
|
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diff
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|
2856 |
|
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diff
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|
2857 |
|
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diff
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|
2858 |
|
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|
2859 <hr><h3><a name="lua_gc"><code>lua_gc</code></a></h3><p> |
|
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|
2860 <span class="apii">[-0, +0, <em>e</em>]</span> |
|
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|
2861 <pre>int lua_gc (lua_State *L, int what, int data);</pre> |
|
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|
2862 |
|
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|
2863 <p> |
|
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|
2864 Controls the garbage collector. |
|
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diff
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|
2865 |
|
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|
2866 |
|
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|
2867 <p> |
|
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|
2868 This function performs several tasks, |
|
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diff
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|
2869 according to the value of the parameter <code>what</code>: |
|
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|
2870 |
|
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diff
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|
2871 <ul> |
|
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diff
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|
2872 |
|
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|
2873 <li><b><code>LUA_GCSTOP</code>: </b> |
|
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|
2874 stops the garbage collector. |
|
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|
2875 </li> |
|
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|
2876 |
|
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|
2877 <li><b><code>LUA_GCRESTART</code>: </b> |
|
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|
2878 restarts the garbage collector. |
|
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|
2879 </li> |
|
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diff
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|
2880 |
|
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|
2881 <li><b><code>LUA_GCCOLLECT</code>: </b> |
|
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|
2882 performs a full garbage-collection cycle. |
|
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|
2883 </li> |
|
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|
2884 |
|
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|
2885 <li><b><code>LUA_GCCOUNT</code>: </b> |
|
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|
2886 returns the current amount of memory (in Kbytes) in use by Lua. |
|
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|
2887 </li> |
|
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diff
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|
2888 |
|
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|
2889 <li><b><code>LUA_GCCOUNTB</code>: </b> |
|
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|
2890 returns the remainder of dividing the current amount of bytes of |
|
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parents:
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|
2891 memory in use by Lua by 1024. |
|
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|
2892 </li> |
|
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diff
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|
2893 |
|
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|
2894 <li><b><code>LUA_GCSTEP</code>: </b> |
|
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|
2895 performs an incremental step of garbage collection. |
|
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|
2896 </li> |
|
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diff
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|
2897 |
|
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|
2898 <li><b><code>LUA_GCSETPAUSE</code>: </b> |
|
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|
2899 sets <code>data</code> as the new value |
|
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|
2900 for the <em>pause</em> of the collector (see <a href="#2.5">§2.5</a>) |
|
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|
2901 and returns the previous value of the pause. |
|
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|
2902 </li> |
|
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|
2903 |
|
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|
2904 <li><b><code>LUA_GCSETSTEPMUL</code>: </b> |
|
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|
2905 sets <code>data</code> as the new value for the <em>step multiplier</em> of |
|
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|
2906 the collector (see <a href="#2.5">§2.5</a>) |
|
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|
2907 and returns the previous value of the step multiplier. |
|
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|
2908 </li> |
|
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|
2909 |
|
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|
2910 <li><b><code>LUA_GCISRUNNING</code>: </b> |
|
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|
2911 returns a boolean that tells whether the collector is running |
|
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|
2912 (i.e., not stopped). |
|
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|
2913 </li> |
|
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|
2914 |
|
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|
2915 </ul> |
|
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|
2916 |
|
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|
2917 <p> |
|
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|
2918 For more details about these options, |
|
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|
2919 see <a href="#pdf-collectgarbage"><code>collectgarbage</code></a>. |
|
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|
2920 |
|
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|
2921 |
|
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diff
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|
2922 |
|
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diff
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|
2923 |
|
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|
2924 |
|
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|
2925 <hr><h3><a name="lua_getallocf"><code>lua_getallocf</code></a></h3><p> |
|
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|
2926 <span class="apii">[-0, +0, –]</span> |
|
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|
2927 <pre>lua_Alloc lua_getallocf (lua_State *L, void **ud);</pre> |
|
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|
2928 |
|
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|
2929 <p> |
|
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|
2930 Returns the memory-allocation function of a given state. |
|
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|
2931 If <code>ud</code> is not <code>NULL</code>, Lua stores in <code>*ud</code> the |
|
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|
2932 opaque pointer given when the memory-allocator function was set. |
|
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|
2933 |
|
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diff
changeset
|
2934 |
|
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diff
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|
2935 |
|
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|
2936 |
|
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|
2937 |
|
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|
2938 <hr><h3><a name="lua_getfield"><code>lua_getfield</code></a></h3><p> |
|
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|
2939 <span class="apii">[-0, +1, <em>e</em>]</span> |
|
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|
2940 <pre>int lua_getfield (lua_State *L, int index, const char *k);</pre> |
|
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|
2941 |
|
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|
2942 <p> |
|
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|
2943 Pushes onto the stack the value <code>t[k]</code>, |
|
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|
2944 where <code>t</code> is the value at the given index. |
|
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|
2945 As in Lua, this function may trigger a metamethod |
|
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|
2946 for the "index" event (see <a href="#2.4">§2.4</a>). |
|
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|
2947 |
|
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|
2948 |
|
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|
2949 <p> |
|
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|
2950 Returns the type of the pushed value. |
|
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|
2951 |
|
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|
2952 |
|
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|
2953 |
|
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|
2954 |
|
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|
2955 |
|
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|
2956 <hr><h3><a name="lua_getextraspace"><code>lua_getextraspace</code></a></h3><p> |
|
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|
2957 <span class="apii">[-0, +0, –]</span> |
|
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|
2958 <pre>void *lua_getextraspace (lua_State *L);</pre> |
|
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|
2959 |
|
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|
2960 <p> |
|
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|
2961 Returns a pointer to a raw memory area associated with the |
|
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|
2962 given Lua state. |
|
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|
2963 The application can use this area for any purpose; |
|
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|
2964 Lua does not use it for anything. |
|
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|
2965 |
|
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|
2966 |
|
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|
2967 <p> |
|
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|
2968 Each new thread has this area initialized with a copy |
|
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|
2969 of the area of the main thread. |
|
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|
2970 |
|
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|
2971 |
|
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|
2972 <p> |
|
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|
2973 By default, this area has the size of a pointer to void, |
|
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|
2974 but you can recompile Lua with a different size for this area. |
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|
2975 (See <code>LUA_EXTRASPACE</code> in <code>luaconf.h</code>.) |
|
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|
2976 |
|
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diff
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|
2977 |
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diff
changeset
|
2978 |
|
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diff
changeset
|
2979 |
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diff
changeset
|
2980 |
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|
2981 <hr><h3><a name="lua_getglobal"><code>lua_getglobal</code></a></h3><p> |
|
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|
2982 <span class="apii">[-0, +1, <em>e</em>]</span> |
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|
2983 <pre>int lua_getglobal (lua_State *L, const char *name);</pre> |
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|
2984 |
|
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|
2985 <p> |
|
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|
2986 Pushes onto the stack the value of the global <code>name</code>. |
|
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|
2987 Returns the type of that value. |
|
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diff
changeset
|
2988 |
|
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diff
changeset
|
2989 |
|
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diff
changeset
|
2990 |
|
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diff
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|
2991 |
|
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|
2992 |
|
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|
2993 <hr><h3><a name="lua_geti"><code>lua_geti</code></a></h3><p> |
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|
2994 <span class="apii">[-0, +1, <em>e</em>]</span> |
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|
2995 <pre>int lua_geti (lua_State *L, int index, lua_Integer i);</pre> |
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|
2996 |
|
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|
2997 <p> |
|
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|
2998 Pushes onto the stack the value <code>t[i]</code>, |
|
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|
2999 where <code>t</code> is the value at the given index. |
|
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|
3000 As in Lua, this function may trigger a metamethod |
|
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|
3001 for the "index" event (see <a href="#2.4">§2.4</a>). |
|
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|
3002 |
|
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|
3003 |
|
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|
3004 <p> |
|
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|
3005 Returns the type of the pushed value. |
|
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|
3006 |
|
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diff
changeset
|
3007 |
|
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diff
changeset
|
3008 |
|
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diff
changeset
|
3009 |
|
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diff
changeset
|
3010 |
|
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|
3011 <hr><h3><a name="lua_getmetatable"><code>lua_getmetatable</code></a></h3><p> |
|
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|
3012 <span class="apii">[-0, +(0|1), –]</span> |
|
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|
3013 <pre>int lua_getmetatable (lua_State *L, int index);</pre> |
|
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|
3014 |
|
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|
3015 <p> |
|
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|
3016 If the value at the given index has a metatable, |
|
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parents:
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|
3017 the function pushes that metatable onto the stack and returns 1. |
|
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|
3018 Otherwise, |
|
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|
3019 the function returns 0 and pushes nothing on the stack. |
|
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|
3020 |
|
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diff
changeset
|
3021 |
|
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diff
changeset
|
3022 |
|
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diff
changeset
|
3023 |
|
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diff
changeset
|
3024 |
|
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|
3025 <hr><h3><a name="lua_gettable"><code>lua_gettable</code></a></h3><p> |
|
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|
3026 <span class="apii">[-1, +1, <em>e</em>]</span> |
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|
3027 <pre>int lua_gettable (lua_State *L, int index);</pre> |
|
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|
3028 |
|
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|
3029 <p> |
|
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|
3030 Pushes onto the stack the value <code>t[k]</code>, |
|
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|
3031 where <code>t</code> is the value at the given index |
|
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|
3032 and <code>k</code> is the value at the top of the stack. |
|
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|
3033 |
|
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diff
changeset
|
3034 |
|
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|
3035 <p> |
|
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|
3036 This function pops the key from the stack, |
|
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|
3037 pushing the resulting value in its place. |
|
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|
3038 As in Lua, this function may trigger a metamethod |
|
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|
3039 for the "index" event (see <a href="#2.4">§2.4</a>). |
|
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|
3040 |
|
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parents:
diff
changeset
|
3041 |
|
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|
3042 <p> |
|
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|
3043 Returns the type of the pushed value. |
|
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diff
changeset
|
3044 |
|
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diff
changeset
|
3045 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3046 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3047 |
|
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diff
changeset
|
3048 |
|
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diff
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|
3049 <hr><h3><a name="lua_gettop"><code>lua_gettop</code></a></h3><p> |
|
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|
3050 <span class="apii">[-0, +0, –]</span> |
|
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diff
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|
3051 <pre>int lua_gettop (lua_State *L);</pre> |
|
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|
3052 |
|
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|
3053 <p> |
|
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diff
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|
3054 Returns the index of the top element in the stack. |
|
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parents:
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changeset
|
3055 Because indices start at 1, |
|
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diff
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|
3056 this result is equal to the number of elements in the stack; |
|
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parents:
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|
3057 in particular, 0 means an empty stack. |
|
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diff
changeset
|
3058 |
|
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diff
changeset
|
3059 |
|
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diff
changeset
|
3060 |
|
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diff
changeset
|
3061 |
|
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diff
changeset
|
3062 |
|
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|
3063 <hr><h3><a name="lua_getuservalue"><code>lua_getuservalue</code></a></h3><p> |
|
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|
3064 <span class="apii">[-0, +1, –]</span> |
|
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|
3065 <pre>int lua_getuservalue (lua_State *L, int index);</pre> |
|
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|
3066 |
|
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|
3067 <p> |
|
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|
3068 Pushes onto the stack the Lua value associated with the userdata |
|
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|
3069 at the given index. |
|
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changeset
|
3070 |
|
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diff
changeset
|
3071 |
|
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|
3072 <p> |
|
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|
3073 Returns the type of the pushed value. |
|
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changeset
|
3074 |
|
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diff
changeset
|
3075 |
|
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diff
changeset
|
3076 |
|
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changeset
|
3077 |
|
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changeset
|
3078 |
|
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|
3079 <hr><h3><a name="lua_insert"><code>lua_insert</code></a></h3><p> |
|
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|
3080 <span class="apii">[-1, +1, –]</span> |
|
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|
3081 <pre>void lua_insert (lua_State *L, int index);</pre> |
|
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changeset
|
3082 |
|
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|
3083 <p> |
|
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|
3084 Moves the top element into the given valid index, |
|
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|
3085 shifting up the elements above this index to open space. |
|
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changeset
|
3086 This function cannot be called with a pseudo-index, |
|
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changeset
|
3087 because a pseudo-index is not an actual stack position. |
|
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changeset
|
3088 |
|
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changeset
|
3089 |
|
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changeset
|
3090 |
|
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|
3091 |
|
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diff
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|
3092 |
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|
3093 <hr><h3><a name="lua_Integer"><code>lua_Integer</code></a></h3> |
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3094 <pre>typedef ... lua_Integer;</pre> |
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3095 |
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|
3096 <p> |
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|
3097 The type of integers in Lua. |
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|
3098 |
|
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|
3099 |
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|
3100 <p> |
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|
3101 By default this type is <code>long long</code>, |
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|
3102 (usually a 64-bit two-complement integer), |
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|
3103 but that can be changed to <code>long</code> or <code>int</code> |
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3104 (usually a 32-bit two-complement integer). |
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|
3105 (See <code>LUA_INT</code> in <code>luaconf.h</code>.) |
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3106 |
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|
3107 |
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3108 <p> |
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|
3109 Lua also defines the constants |
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3110 <a name="pdf-LUA_MININTEGER"><code>LUA_MININTEGER</code></a> and <a name="pdf-LUA_MAXINTEGER"><code>LUA_MAXINTEGER</code></a>, |
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|
3111 with the minimum and the maximum values that fit in this type. |
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|
3112 |
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|
3113 |
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|
3114 |
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|
3115 |
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3116 |
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3117 <hr><h3><a name="lua_isboolean"><code>lua_isboolean</code></a></h3><p> |
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3118 <span class="apii">[-0, +0, –]</span> |
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|
3119 <pre>int lua_isboolean (lua_State *L, int index);</pre> |
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|
3120 |
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|
3121 <p> |
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|
3122 Returns 1 if the value at the given index is a boolean, |
|
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|
3123 and 0 otherwise. |
|
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|
3124 |
|
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diff
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|
3125 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
3126 |
|
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diff
changeset
|
3127 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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|
3128 |
|
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|
3129 <hr><h3><a name="lua_iscfunction"><code>lua_iscfunction</code></a></h3><p> |
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|
3130 <span class="apii">[-0, +0, –]</span> |
|
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|
3131 <pre>int lua_iscfunction (lua_State *L, int index);</pre> |
|
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|
3132 |
|
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|
3133 <p> |
|
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|
3134 Returns 1 if the value at the given index is a C function, |
|
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|
3135 and 0 otherwise. |
|
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diff
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|
3136 |
|
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diff
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|
3137 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
3138 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3139 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3140 |
|
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|
3141 <hr><h3><a name="lua_isfunction"><code>lua_isfunction</code></a></h3><p> |
|
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|
3142 <span class="apii">[-0, +0, –]</span> |
|
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|
3143 <pre>int lua_isfunction (lua_State *L, int index);</pre> |
|
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|
3144 |
|
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|
3145 <p> |
|
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|
3146 Returns 1 if the value at the given index is a function |
|
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|
3147 (either C or Lua), and 0 otherwise. |
|
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|
3148 |
|
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diff
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|
3149 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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|
3150 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
3151 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
3152 |
|
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|
3153 <hr><h3><a name="lua_isinteger"><code>lua_isinteger</code></a></h3><p> |
|
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|
3154 <span class="apii">[-0, +0, –]</span> |
|
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|
3155 <pre>int lua_isinteger (lua_State *L, int index);</pre> |
|
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|
3156 |
|
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|
3157 <p> |
|
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|
3158 Returns 1 if the value at the given index is an integer |
|
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|
3159 (that is, the value is a number and is represented as an integer), |
|
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|
3160 and 0 otherwise. |
|
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diff
changeset
|
3161 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3162 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3163 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3164 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
3165 |
|
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|
3166 <hr><h3><a name="lua_islightuserdata"><code>lua_islightuserdata</code></a></h3><p> |
|
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|
3167 <span class="apii">[-0, +0, –]</span> |
|
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diff
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|
3168 <pre>int lua_islightuserdata (lua_State *L, int index);</pre> |
|
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|
3169 |
|
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|
3170 <p> |
|
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parents:
diff
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|
3171 Returns 1 if the value at the given index is a light userdata, |
|
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parents:
diff
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|
3172 and 0 otherwise. |
|
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parents:
diff
changeset
|
3173 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3174 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3175 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3176 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3177 |
|
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|
3178 <hr><h3><a name="lua_isnil"><code>lua_isnil</code></a></h3><p> |
|
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|
3179 <span class="apii">[-0, +0, –]</span> |
|
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|
3180 <pre>int lua_isnil (lua_State *L, int index);</pre> |
|
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|
3181 |
|
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|
3182 <p> |
|
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|
3183 Returns 1 if the value at the given index is <b>nil</b>, |
|
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|
3184 and 0 otherwise. |
|
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parents:
diff
changeset
|
3185 |
|
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changeset
|
3186 |
|
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changeset
|
3187 |
|
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|
3188 |
|
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|
3189 |
|
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|
3190 <hr><h3><a name="lua_isnone"><code>lua_isnone</code></a></h3><p> |
|
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3191 <span class="apii">[-0, +0, –]</span> |
|
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|
3192 <pre>int lua_isnone (lua_State *L, int index);</pre> |
|
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|
3193 |
|
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|
3194 <p> |
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3195 Returns 1 if the given index is not valid, |
|
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changeset
|
3196 and 0 otherwise. |
|
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changeset
|
3197 |
|
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changeset
|
3198 |
|
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changeset
|
3199 |
|
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changeset
|
3200 |
|
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changeset
|
3201 |
|
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|
3202 <hr><h3><a name="lua_isnoneornil"><code>lua_isnoneornil</code></a></h3><p> |
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3203 <span class="apii">[-0, +0, –]</span> |
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|
3204 <pre>int lua_isnoneornil (lua_State *L, int index);</pre> |
|
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|
3205 |
|
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3206 <p> |
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|
3207 Returns 1 if the given index is not valid |
|
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|
3208 or if the value at this index is <b>nil</b>, |
|
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parents:
diff
changeset
|
3209 and 0 otherwise. |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3210 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3211 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3212 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3213 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3214 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3215 <hr><h3><a name="lua_isnumber"><code>lua_isnumber</code></a></h3><p> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
3216 <span class="apii">[-0, +0, –]</span> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
3217 <pre>int lua_isnumber (lua_State *L, int index);</pre> |
|
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diff
changeset
|
3218 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3219 <p> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3220 Returns 1 if the value at the given index is a number |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3221 or a string convertible to a number, |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3222 and 0 otherwise. |
|
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parents:
diff
changeset
|
3223 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3224 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3225 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3226 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3227 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3228 <hr><h3><a name="lua_isstring"><code>lua_isstring</code></a></h3><p> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
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|
3229 <span class="apii">[-0, +0, –]</span> |
|
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parents:
diff
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|
3230 <pre>int lua_isstring (lua_State *L, int index);</pre> |
|
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diff
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|
3231 |
|
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diff
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|
3232 <p> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
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|
3233 Returns 1 if the value at the given index is a string |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
3234 or a number (which is always convertible to a string), |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3235 and 0 otherwise. |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3236 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3237 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3238 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3239 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3240 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
3241 <hr><h3><a name="lua_istable"><code>lua_istable</code></a></h3><p> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
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|
3242 <span class="apii">[-0, +0, –]</span> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
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|
3243 <pre>int lua_istable (lua_State *L, int index);</pre> |
|
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diff
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|
3244 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3245 <p> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
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|
3246 Returns 1 if the value at the given index is a table, |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3247 and 0 otherwise. |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3248 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3249 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3250 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3251 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3252 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
3253 <hr><h3><a name="lua_isthread"><code>lua_isthread</code></a></h3><p> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
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|
3254 <span class="apii">[-0, +0, –]</span> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
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|
3255 <pre>int lua_isthread (lua_State *L, int index);</pre> |
|
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diff
changeset
|
3256 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3257 <p> |
|
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parents:
diff
changeset
|
3258 Returns 1 if the value at the given index is a thread, |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
3259 and 0 otherwise. |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3260 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3261 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3262 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3263 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3264 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3265 <hr><h3><a name="lua_isuserdata"><code>lua_isuserdata</code></a></h3><p> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
3266 <span class="apii">[-0, +0, –]</span> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3267 <pre>int lua_isuserdata (lua_State *L, int index);</pre> |
|
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diff
changeset
|
3268 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3269 <p> |
|
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parents:
diff
changeset
|
3270 Returns 1 if the value at the given index is a userdata |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
3271 (either full or light), and 0 otherwise. |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3272 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3273 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3274 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3275 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3276 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3277 <hr><h3><a name="lua_isyieldable"><code>lua_isyieldable</code></a></h3><p> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3278 <span class="apii">[-0, +0, –]</span> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
3279 <pre>int lua_isyieldable (lua_State *L);</pre> |
|
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parents:
diff
changeset
|
3280 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3281 <p> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3282 Returns 1 if the given coroutine can yield, |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
3283 and 0 otherwise. |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3284 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3285 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3286 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3287 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3288 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3289 <hr><h3><a name="lua_KContext"><code>lua_KContext</code></a></h3> |
|
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parents:
diff
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|
3290 <pre>typedef ... lua_KContext;</pre> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3291 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3292 <p> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3293 The type for continuation-function contexts. |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3294 It must be a numerical type. |
|
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parents:
diff
changeset
|
3295 This type is defined as <code>intptr_t</code> |
|
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parents:
diff
changeset
|
3296 when <code>intptr_t</code> is available, |
|
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parents:
diff
changeset
|
3297 so that it can store pointers too. |
|
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parents:
diff
changeset
|
3298 Otherwise, it is defined as <code>ptrdiff_t</code>. |
|
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parents:
diff
changeset
|
3299 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3300 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3301 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3302 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3303 |
|
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parents:
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|
3304 <hr><h3><a name="lua_KFunction"><code>lua_KFunction</code></a></h3> |
|
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|
3305 <pre>typedef int (*lua_KFunction) (lua_State *L, int status, lua_KContext ctx);</pre> |
|
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changeset
|
3306 |
|
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diff
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|
3307 <p> |
|
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diff
changeset
|
3308 Type for continuation functions (see <a href="#4.7">§4.7</a>). |
|
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parents:
diff
changeset
|
3309 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3310 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3311 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3312 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3313 |
|
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|
3314 <hr><h3><a name="lua_len"><code>lua_len</code></a></h3><p> |
|
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|
3315 <span class="apii">[-0, +1, <em>e</em>]</span> |
|
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diff
changeset
|
3316 <pre>void lua_len (lua_State *L, int index);</pre> |
|
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changeset
|
3317 |
|
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diff
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|
3318 <p> |
|
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diff
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|
3319 Returns the length of the value at the given index. |
|
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parents:
diff
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|
3320 It is equivalent to the '<code>#</code>' operator in Lua (see <a href="#3.4.7">§3.4.7</a>) and |
|
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diff
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|
3321 may trigger a metamethod for the "length" event (see <a href="#2.4">§2.4</a>). |
|
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|
3322 The result is pushed on the stack. |
|
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parents:
diff
changeset
|
3323 |
|
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parents:
diff
changeset
|
3324 |
|
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parents:
diff
changeset
|
3325 |
|
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parents:
diff
changeset
|
3326 |
|
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parents:
diff
changeset
|
3327 |
|
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|
3328 <hr><h3><a name="lua_load"><code>lua_load</code></a></h3><p> |
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3329 <span class="apii">[-0, +1, –]</span> |
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|
3330 <pre>int lua_load (lua_State *L, |
|
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|
3331 lua_Reader reader, |
|
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3332 void *data, |
|
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|
3333 const char *chunkname, |
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|
3334 const char *mode);</pre> |
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3335 |
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3336 <p> |
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|
3337 Loads a Lua chunk without running it. |
|
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|
3338 If there are no errors, |
|
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|
3339 <code>lua_load</code> pushes the compiled chunk as a Lua |
|
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|
3340 function on top of the stack. |
|
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|
3341 Otherwise, it pushes an error message. |
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3342 |
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3343 |
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3344 <p> |
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|
3345 The return values of <code>lua_load</code> are: |
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3346 |
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3347 <ul> |
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3348 |
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|
3349 <li><b><a href="#pdf-LUA_OK"><code>LUA_OK</code></a>: </b> no errors;</li> |
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3350 |
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|
3351 <li><b><a name="pdf-LUA_ERRSYNTAX"><code>LUA_ERRSYNTAX</code></a>: </b> |
|
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|
3352 syntax error during precompilation;</li> |
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3353 |
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3354 <li><b><a href="#pdf-LUA_ERRMEM"><code>LUA_ERRMEM</code></a>: </b> |
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3355 memory allocation error;</li> |
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3356 |
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3357 <li><b><a href="#pdf-LUA_ERRGCMM"><code>LUA_ERRGCMM</code></a>: </b> |
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3358 error while running a <code>__gc</code> metamethod. |
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3359 (This error has no relation with the chunk being loaded. |
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3360 It is generated by the garbage collector.) |
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3361 </li> |
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3362 |
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|
3363 </ul> |
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3364 |
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|
3365 <p> |
|
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|
3366 The <code>lua_load</code> function uses a user-supplied <code>reader</code> function |
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|
3367 to read the chunk (see <a href="#lua_Reader"><code>lua_Reader</code></a>). |
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3368 The <code>data</code> argument is an opaque value passed to the reader function. |
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3369 |
|
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|
3370 |
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|
3371 <p> |
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|
3372 The <code>chunkname</code> argument gives a name to the chunk, |
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|
3373 which is used for error messages and in debug information (see <a href="#4.9">§4.9</a>). |
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3374 |
|
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3375 |
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|
3376 <p> |
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|
3377 <code>lua_load</code> automatically detects whether the chunk is text or binary |
|
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3378 and loads it accordingly (see program <code>luac</code>). |
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|
3379 The string <code>mode</code> works as in function <a href="#pdf-load"><code>load</code></a>, |
|
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|
3380 with the addition that |
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|
3381 a <code>NULL</code> value is equivalent to the string "<code>bt</code>". |
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3382 |
|
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3383 |
|
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|
3384 <p> |
|
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|
3385 <code>lua_load</code> uses the stack internally, |
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|
3386 so the reader function must always leave the stack |
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|
3387 unmodified when returning. |
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3388 |
|
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3389 |
|
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|
3390 <p> |
|
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|
3391 If the resulting function has upvalues, |
|
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|
3392 its first upvalue is set to the value of the global environment |
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|
3393 stored at index <code>LUA_RIDX_GLOBALS</code> in the registry (see <a href="#4.5">§4.5</a>). |
|
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|
3394 When loading main chunks, |
|
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|
3395 this upvalue will be the <code>_ENV</code> variable (see <a href="#2.2">§2.2</a>). |
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|
3396 Other upvalues are initialized with <b>nil</b>. |
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|
3397 |
|
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|
3398 |
|
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|
3399 |
|
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|
3400 |
|
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|
3401 |
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|
3402 <hr><h3><a name="lua_newstate"><code>lua_newstate</code></a></h3><p> |
|
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|
3403 <span class="apii">[-0, +0, –]</span> |
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|
3404 <pre>lua_State *lua_newstate (lua_Alloc f, void *ud);</pre> |
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3405 |
|
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|
3406 <p> |
|
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|
3407 Creates a new thread running in a new, independent state. |
|
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|
3408 Returns <code>NULL</code> if it cannot create the thread or the state |
|
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|
3409 (due to lack of memory). |
|
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|
3410 The argument <code>f</code> is the allocator function; |
|
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|
3411 Lua does all memory allocation for this state through this function. |
|
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|
3412 The second argument, <code>ud</code>, is an opaque pointer that Lua |
|
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|
3413 passes to the allocator in every call. |
|
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|
3414 |
|
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|
3415 |
|
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|
3416 |
|
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|
3417 |
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|
3418 |
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|
3419 <hr><h3><a name="lua_newtable"><code>lua_newtable</code></a></h3><p> |
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3420 <span class="apii">[-0, +1, <em>e</em>]</span> |
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|
3421 <pre>void lua_newtable (lua_State *L);</pre> |
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3422 |
|
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|
3423 <p> |
|
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|
3424 Creates a new empty table and pushes it onto the stack. |
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|
3425 It is equivalent to <code>lua_createtable(L, 0, 0)</code>. |
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|
3426 |
|
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|
3427 |
|
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|
3428 |
|
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|
3429 |
|
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|
3430 |
|
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|
3431 <hr><h3><a name="lua_newthread"><code>lua_newthread</code></a></h3><p> |
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|
3432 <span class="apii">[-0, +1, <em>e</em>]</span> |
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|
3433 <pre>lua_State *lua_newthread (lua_State *L);</pre> |
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|
3434 |
|
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|
3435 <p> |
|
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|
3436 Creates a new thread, pushes it on the stack, |
|
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|
3437 and returns a pointer to a <a href="#lua_State"><code>lua_State</code></a> that represents this new thread. |
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3438 The new thread returned by this function shares with the original thread |
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3439 its global environment, |
|
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|
3440 but has an independent execution stack. |
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|
3441 |
|
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|
3442 |
|
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changeset
|
3443 <p> |
|
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changeset
|
3444 There is no explicit function to close or to destroy a thread. |
|
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diff
changeset
|
3445 Threads are subject to garbage collection, |
|
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|
3446 like any Lua object. |
|
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|
3447 |
|
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diff
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|
3448 |
|
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diff
changeset
|
3449 |
|
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diff
changeset
|
3450 |
|
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diff
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|
3451 |
|
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|
3452 <hr><h3><a name="lua_newuserdata"><code>lua_newuserdata</code></a></h3><p> |
|
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|
3453 <span class="apii">[-0, +1, <em>e</em>]</span> |
|
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|
3454 <pre>void *lua_newuserdata (lua_State *L, size_t size);</pre> |
|
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|
3455 |
|
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diff
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|
3456 <p> |
|
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diff
changeset
|
3457 This function allocates a new block of memory with the given size, |
|
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diff
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|
3458 pushes onto the stack a new full userdata with the block address, |
|
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|
3459 and returns this address. |
|
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|
3460 The host program can freely use this memory. |
|
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diff
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|
3461 |
|
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diff
changeset
|
3462 |
|
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diff
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|
3463 |
|
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diff
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|
3464 |
|
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diff
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|
3465 |
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|
3466 <hr><h3><a name="lua_next"><code>lua_next</code></a></h3><p> |
|
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|
3467 <span class="apii">[-1, +(2|0), <em>e</em>]</span> |
|
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|
3468 <pre>int lua_next (lua_State *L, int index);</pre> |
|
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|
3469 |
|
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|
3470 <p> |
|
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|
3471 Pops a key from the stack, |
|
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|
3472 and pushes a key–value pair from the table at the given index |
|
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|
3473 (the "next" pair after the given key). |
|
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|
3474 If there are no more elements in the table, |
|
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|
3475 then <a href="#lua_next"><code>lua_next</code></a> returns 0 (and pushes nothing). |
|
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|
3476 |
|
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diff
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|
3477 |
|
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|
3478 <p> |
|
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|
3479 A typical traversal looks like this: |
|
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|
3480 |
|
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|
3481 <pre> |
|
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|
3482 /* table is in the stack at index 't' */ |
|
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|
3483 lua_pushnil(L); /* first key */ |
|
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|
3484 while (lua_next(L, t) != 0) { |
|
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|
3485 /* uses 'key' (at index -2) and 'value' (at index -1) */ |
|
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|
3486 printf("%s - %s\n", |
|
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|
3487 lua_typename(L, lua_type(L, -2)), |
|
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|
3488 lua_typename(L, lua_type(L, -1))); |
|
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|
3489 /* removes 'value'; keeps 'key' for next iteration */ |
|
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|
3490 lua_pop(L, 1); |
|
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|
3491 } |
|
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|
3492 </pre> |
|
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|
3493 |
|
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|
3494 <p> |
|
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|
3495 While traversing a table, |
|
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|
3496 do not call <a href="#lua_tolstring"><code>lua_tolstring</code></a> directly on a key, |
|
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|
3497 unless you know that the key is actually a string. |
|
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|
3498 Recall that <a href="#lua_tolstring"><code>lua_tolstring</code></a> may change |
|
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|
3499 the value at the given index; |
|
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|
3500 this confuses the next call to <a href="#lua_next"><code>lua_next</code></a>. |
|
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|
3501 |
|
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|
3502 |
|
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|
3503 <p> |
|
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|
3504 See function <a href="#pdf-next"><code>next</code></a> for the caveats of modifying |
|
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|
3505 the table during its traversal. |
|
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|
3506 |
|
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diff
changeset
|
3507 |
|
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diff
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|
3508 |
|
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diff
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|
3509 |
|
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diff
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|
3510 |
|
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|
3511 <hr><h3><a name="lua_Number"><code>lua_Number</code></a></h3> |
|
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|
3512 <pre>typedef double lua_Number;</pre> |
|
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|
3513 |
|
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|
3514 <p> |
|
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|
3515 The type of floats in Lua. |
|
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|
3516 |
|
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diff
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|
3517 |
|
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|
3518 <p> |
|
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diff
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|
3519 By default this type is double, |
|
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diff
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|
3520 but that can be changed to a single float. |
|
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|
3521 (See <code>LUA_REAL</code> in <code>luaconf.h</code>.) |
|
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|
3522 |
|
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diff
changeset
|
3523 |
|
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diff
changeset
|
3524 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3525 |
|
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diff
changeset
|
3526 |
|
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|
3527 <hr><h3><a name="lua_numbertointeger"><code>lua_numbertointeger</code></a></h3> |
|
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|
3528 <pre>int lua_numbertointeger (lua_Number n, lua_Integer *p);</pre> |
|
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|
3529 |
|
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|
3530 <p> |
|
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|
3531 Converts a Lua float to a Lua integer. |
|
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|
3532 This macro assumes that <code>n</code> has an integral value. |
|
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|
3533 If that value is within the range of Lua integers, |
|
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|
3534 it is converted to an integer and assigned to <code>*p</code>. |
|
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|
3535 The macro results in a boolean indicating whether the |
|
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|
3536 conversion was successful. |
|
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|
3537 (Note that this range test can be tricky to do |
|
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|
3538 correctly without this macro, |
|
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|
3539 due to roundings.) |
|
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|
3540 |
|
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|
3541 |
|
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|
3542 <p> |
|
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|
3543 This macro may evaluate its arguments more than once. |
|
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|
3544 |
|
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|
3545 |
|
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|
3546 |
|
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|
3547 |
|
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|
3548 |
|
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|
3549 <hr><h3><a name="lua_pcall"><code>lua_pcall</code></a></h3><p> |
|
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|
3550 <span class="apii">[-(nargs + 1), +(nresults|1), –]</span> |
|
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|
3551 <pre>int lua_pcall (lua_State *L, int nargs, int nresults, int msgh);</pre> |
|
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|
3552 |
|
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|
3553 <p> |
|
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|
3554 Calls a function in protected mode. |
|
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|
3555 |
|
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|
3556 |
|
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|
3557 <p> |
|
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|
3558 Both <code>nargs</code> and <code>nresults</code> have the same meaning as |
|
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|
3559 in <a href="#lua_call"><code>lua_call</code></a>. |
|
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|
3560 If there are no errors during the call, |
|
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changeset
|
3561 <a href="#lua_pcall"><code>lua_pcall</code></a> behaves exactly like <a href="#lua_call"><code>lua_call</code></a>. |
|
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|
3562 However, if there is any error, |
|
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|
3563 <a href="#lua_pcall"><code>lua_pcall</code></a> catches it, |
|
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|
3564 pushes a single value on the stack (the error message), |
|
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|
3565 and returns an error code. |
|
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|
3566 Like <a href="#lua_call"><code>lua_call</code></a>, |
|
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|
3567 <a href="#lua_pcall"><code>lua_pcall</code></a> always removes the function |
|
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|
3568 and its arguments from the stack. |
|
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|
3569 |
|
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|
3570 |
|
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|
3571 <p> |
|
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|
3572 If <code>msgh</code> is 0, |
|
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|
3573 then the error message returned on the stack |
|
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|
3574 is exactly the original error message. |
|
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|
3575 Otherwise, <code>msgh</code> is the stack index of a |
|
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|
3576 <em>message handler</em>. |
|
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|
3577 (In the current implementation, this index cannot be a pseudo-index.) |
|
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|
3578 In case of runtime errors, |
|
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|
3579 this function will be called with the error message |
|
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|
3580 and its return value will be the message |
|
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|
3581 returned on the stack by <a href="#lua_pcall"><code>lua_pcall</code></a>. |
|
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|
3582 |
|
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|
3583 |
|
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|
3584 <p> |
|
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|
3585 Typically, the message handler is used to add more debug |
|
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|
3586 information to the error message, such as a stack traceback. |
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3587 Such information cannot be gathered after the return of <a href="#lua_pcall"><code>lua_pcall</code></a>, |
|
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3588 since by then the stack has unwound. |
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|
3589 |
|
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|
3590 |
|
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|
3591 <p> |
|
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|
3592 The <a href="#lua_pcall"><code>lua_pcall</code></a> function returns one of the following constants |
|
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|
3593 (defined in <code>lua.h</code>): |
|
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|
3594 |
|
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|
3595 <ul> |
|
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|
3596 |
|
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|
3597 <li><b><a name="pdf-LUA_OK"><code>LUA_OK</code></a> (0): </b> |
|
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|
3598 success.</li> |
|
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|
3599 |
|
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|
3600 <li><b><a name="pdf-LUA_ERRRUN"><code>LUA_ERRRUN</code></a>: </b> |
|
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|
3601 a runtime error. |
|
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|
3602 </li> |
|
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|
3603 |
|
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|
3604 <li><b><a name="pdf-LUA_ERRMEM"><code>LUA_ERRMEM</code></a>: </b> |
|
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|
3605 memory allocation error. |
|
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|
3606 For such errors, Lua does not call the message handler. |
|
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|
3607 </li> |
|
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|
3608 |
|
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|
3609 <li><b><a name="pdf-LUA_ERRERR"><code>LUA_ERRERR</code></a>: </b> |
|
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|
3610 error while running the message handler. |
|
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|
3611 </li> |
|
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|
3612 |
|
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|
3613 <li><b><a name="pdf-LUA_ERRGCMM"><code>LUA_ERRGCMM</code></a>: </b> |
|
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|
3614 error while running a <code>__gc</code> metamethod. |
|
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|
3615 (This error typically has no relation with the function being called.) |
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|
3616 </li> |
|
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|
3617 |
|
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|
3618 </ul> |
|
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|
3619 |
|
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|
3620 |
|
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|
3621 |
|
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|
3622 |
|
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|
3623 <hr><h3><a name="lua_pcallk"><code>lua_pcallk</code></a></h3><p> |
|
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|
3624 <span class="apii">[-(nargs + 1), +(nresults|1), –]</span> |
|
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|
3625 <pre>int lua_pcallk (lua_State *L, |
|
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|
3626 int nargs, |
|
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|
3627 int nresults, |
|
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|
3628 int msgh, |
|
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|
3629 lua_KContext ctx, |
|
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|
3630 lua_KFunction k);</pre> |
|
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|
3631 |
|
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|
3632 <p> |
|
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|
3633 This function behaves exactly like <a href="#lua_pcall"><code>lua_pcall</code></a>, |
|
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|
3634 but allows the called function to yield (see <a href="#4.7">§4.7</a>). |
|
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|
3635 |
|
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|
3636 |
|
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|
3637 |
|
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|
3638 |
|
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|
3639 |
|
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|
3640 <hr><h3><a name="lua_pop"><code>lua_pop</code></a></h3><p> |
|
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|
3641 <span class="apii">[-n, +0, –]</span> |
|
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|
3642 <pre>void lua_pop (lua_State *L, int n);</pre> |
|
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|
3643 |
|
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|
3644 <p> |
|
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|
3645 Pops <code>n</code> elements from the stack. |
|
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|
3646 |
|
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|
3647 |
|
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|
3648 |
|
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|
3649 |
|
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|
3650 |
|
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|
3651 <hr><h3><a name="lua_pushboolean"><code>lua_pushboolean</code></a></h3><p> |
|
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|
3652 <span class="apii">[-0, +1, –]</span> |
|
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|
3653 <pre>void lua_pushboolean (lua_State *L, int b);</pre> |
|
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|
3654 |
|
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|
3655 <p> |
|
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|
3656 Pushes a boolean value with value <code>b</code> onto the stack. |
|
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|
3657 |
|
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|
3658 |
|
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|
3659 |
|
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|
3660 |
|
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|
3661 |
|
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|
3662 <hr><h3><a name="lua_pushcclosure"><code>lua_pushcclosure</code></a></h3><p> |
|
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|
3663 <span class="apii">[-n, +1, <em>e</em>]</span> |
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|
3664 <pre>void lua_pushcclosure (lua_State *L, lua_CFunction fn, int n);</pre> |
|
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|
3665 |
|
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|
3666 <p> |
|
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|
3667 Pushes a new C closure onto the stack. |
|
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|
3668 |
|
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|
3669 |
|
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|
3670 <p> |
|
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|
3671 When a C function is created, |
|
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|
3672 it is possible to associate some values with it, |
|
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|
3673 thus creating a C closure (see <a href="#4.4">§4.4</a>); |
|
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|
3674 these values are then accessible to the function whenever it is called. |
|
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|
3675 To associate values with a C function, |
|
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|
3676 first these values must be pushed onto the stack |
|
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changeset
|
3677 (when there are multiple values, the first value is pushed first). |
|
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|
3678 Then <a href="#lua_pushcclosure"><code>lua_pushcclosure</code></a> |
|
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|
3679 is called to create and push the C function onto the stack, |
|
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|
3680 with the argument <code>n</code> telling how many values will be |
|
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|
3681 associated with the function. |
|
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|
3682 <a href="#lua_pushcclosure"><code>lua_pushcclosure</code></a> also pops these values from the stack. |
|
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|
3683 |
|
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|
3684 |
|
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diff
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|
3685 <p> |
|
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|
3686 The maximum value for <code>n</code> is 255. |
|
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|
3687 |
|
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|
3688 |
|
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|
3689 <p> |
|
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|
3690 When <code>n</code> is zero, |
|
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|
3691 this function creates a <em>light C function</em>, |
|
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|
3692 which is just a pointer to the C function. |
|
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|
3693 In that case, it never raises a memory error. |
|
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|
3694 |
|
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|
3695 |
|
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diff
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|
3696 |
|
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diff
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|
3697 |
|
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diff
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|
3698 |
|
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|
3699 <hr><h3><a name="lua_pushcfunction"><code>lua_pushcfunction</code></a></h3><p> |
|
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|
3700 <span class="apii">[-0, +1, –]</span> |
|
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|
3701 <pre>void lua_pushcfunction (lua_State *L, lua_CFunction f);</pre> |
|
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|
3702 |
|
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|
3703 <p> |
|
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|
3704 Pushes a C function onto the stack. |
|
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|
3705 This function receives a pointer to a C function |
|
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|
3706 and pushes onto the stack a Lua value of type <code>function</code> that, |
|
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|
3707 when called, invokes the corresponding C function. |
|
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|
3708 |
|
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diff
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|
3709 |
|
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|
3710 <p> |
|
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|
3711 Any function to be registered in Lua must |
|
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|
3712 follow the correct protocol to receive its parameters |
|
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|
3713 and return its results (see <a href="#lua_CFunction"><code>lua_CFunction</code></a>). |
|
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|
3714 |
|
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diff
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|
3715 |
|
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|
3716 <p> |
|
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|
3717 <code>lua_pushcfunction</code> is defined as a macro: |
|
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|
3718 |
|
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|
3719 <pre> |
|
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|
3720 #define lua_pushcfunction(L,f) lua_pushcclosure(L,f,0) |
|
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|
3721 </pre><p> |
|
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|
3722 Note that <code>f</code> is used twice. |
|
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|
3723 |
|
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diff
changeset
|
3724 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3725 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3726 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
3727 |
|
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|
3728 <hr><h3><a name="lua_pushfstring"><code>lua_pushfstring</code></a></h3><p> |
|
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|
3729 <span class="apii">[-0, +1, <em>e</em>]</span> |
|
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|
3730 <pre>const char *lua_pushfstring (lua_State *L, const char *fmt, ...);</pre> |
|
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|
3731 |
|
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|
3732 <p> |
|
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|
3733 Pushes onto the stack a formatted string |
|
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|
3734 and returns a pointer to this string. |
|
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|
3735 It is similar to the ISO C function <code>sprintf</code>, |
|
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|
3736 but has some important differences: |
|
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|
3737 |
|
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diff
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|
3738 <ul> |
|
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changeset
|
3739 |
|
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|
3740 <li> |
|
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|
3741 You do not have to allocate space for the result: |
|
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|
3742 the result is a Lua string and Lua takes care of memory allocation |
|
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|
3743 (and deallocation, through garbage collection). |
|
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|
3744 </li> |
|
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|
3745 |
|
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diff
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|
3746 <li> |
|
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diff
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|
3747 The conversion specifiers are quite restricted. |
|
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diff
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|
3748 There are no flags, widths, or precisions. |
|
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|
3749 The conversion specifiers can only be |
|
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|
3750 '<code>%%</code>' (inserts the character '<code>%</code>'), |
|
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|
3751 '<code>%s</code>' (inserts a zero-terminated string, with no size restrictions), |
|
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|
3752 '<code>%f</code>' (inserts a <a href="#lua_Number"><code>lua_Number</code></a>), |
|
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|
3753 '<code>%L</code>' (inserts a <a href="#lua_Integer"><code>lua_Integer</code></a>), |
|
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|
3754 '<code>%p</code>' (inserts a pointer as a hexadecimal numeral), |
|
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|
3755 '<code>%d</code>' (inserts an <code>int</code>), |
|
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|
3756 '<code>%c</code>' (inserts an <code>int</code> as a one-byte character), and |
|
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|
3757 '<code>%U</code>' (inserts a <code>long int</code> as a UTF-8 byte sequence). |
|
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|
3758 </li> |
|
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diff
changeset
|
3759 |
|
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changeset
|
3760 </ul> |
|
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diff
changeset
|
3761 |
|
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diff
changeset
|
3762 |
|
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diff
changeset
|
3763 |
|
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|
3764 |
|
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|
3765 <hr><h3><a name="lua_pushglobaltable"><code>lua_pushglobaltable</code></a></h3><p> |
|
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|
3766 <span class="apii">[-0, +1, –]</span> |
|
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|
3767 <pre>void lua_pushglobaltable (lua_State *L);</pre> |
|
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|
3768 |
|
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|
3769 <p> |
|
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changeset
|
3770 Pushes the global environment onto the stack. |
|
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changeset
|
3771 |
|
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changeset
|
3772 |
|
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diff
changeset
|
3773 |
|
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diff
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|
3774 |
|
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|
3775 |
|
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|
3776 <hr><h3><a name="lua_pushinteger"><code>lua_pushinteger</code></a></h3><p> |
|
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|
3777 <span class="apii">[-0, +1, –]</span> |
|
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|
3778 <pre>void lua_pushinteger (lua_State *L, lua_Integer n);</pre> |
|
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|
3779 |
|
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|
3780 <p> |
|
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|
3781 Pushes an integer with value <code>n</code> onto the stack. |
|
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|
3782 |
|
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|
3783 |
|
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|
3784 |
|
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|
3785 |
|
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|
3786 |
|
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|
3787 <hr><h3><a name="lua_pushlightuserdata"><code>lua_pushlightuserdata</code></a></h3><p> |
|
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|
3788 <span class="apii">[-0, +1, –]</span> |
|
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|
3789 <pre>void lua_pushlightuserdata (lua_State *L, void *p);</pre> |
|
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|
3790 |
|
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|
3791 <p> |
|
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changeset
|
3792 Pushes a light userdata onto the stack. |
|
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|
3793 |
|
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diff
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|
3794 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3795 <p> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3796 Userdata represent C values in Lua. |
|
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parents:
diff
changeset
|
3797 A <em>light userdata</em> represents a pointer, a <code>void*</code>. |
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parents:
diff
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|
3798 It is a value (like a number): |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
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|
3799 you do not create it, it has no individual metatable, |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
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|
3800 and it is not collected (as it was never created). |
|
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parents:
diff
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|
3801 A light userdata is equal to "any" |
|
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parents:
diff
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|
3802 light userdata with the same C address. |
|
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parents:
diff
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|
3803 |
|
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diff
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|
3804 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
3805 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3806 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3807 |
|
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|
3808 <hr><h3><a name="lua_pushliteral"><code>lua_pushliteral</code></a></h3><p> |
|
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|
3809 <span class="apii">[-0, +1, <em>e</em>]</span> |
|
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|
3810 <pre>const char *lua_pushliteral (lua_State *L, const char *s);</pre> |
|
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|
3811 |
|
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diff
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|
3812 <p> |
|
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diff
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|
3813 This macro is equivalent to <a href="#lua_pushlstring"><code>lua_pushlstring</code></a>, |
|
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diff
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|
3814 but can be used only when <code>s</code> is a literal string. |
|
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parents:
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|
3815 It automatically provides the string length. |
|
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|
3816 |
|
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diff
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|
3817 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3818 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3819 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3820 |
|
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diff
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|
3821 <hr><h3><a name="lua_pushlstring"><code>lua_pushlstring</code></a></h3><p> |
|
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|
3822 <span class="apii">[-0, +1, <em>e</em>]</span> |
|
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|
3823 <pre>const char *lua_pushlstring (lua_State *L, const char *s, size_t len);</pre> |
|
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|
3824 |
|
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diff
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|
3825 <p> |
|
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parents:
diff
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|
3826 Pushes the string pointed to by <code>s</code> with size <code>len</code> |
|
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|
3827 onto the stack. |
|
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parents:
diff
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|
3828 Lua makes (or reuses) an internal copy of the given string, |
|
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parents:
diff
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|
3829 so the memory at <code>s</code> can be freed or reused immediately after |
|
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|
3830 the function returns. |
|
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parents:
diff
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|
3831 The string can contain any binary data, |
|
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parents:
diff
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|
3832 including embedded zeros. |
|
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parents:
diff
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|
3833 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3834 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
3835 <p> |
|
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parents:
diff
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|
3836 Returns a pointer to the internal copy of the string. |
|
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|
3837 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3838 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3839 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3840 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3841 |
|
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|
3842 <hr><h3><a name="lua_pushnil"><code>lua_pushnil</code></a></h3><p> |
|
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|
3843 <span class="apii">[-0, +1, –]</span> |
|
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parents:
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|
3844 <pre>void lua_pushnil (lua_State *L);</pre> |
|
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|
3845 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3846 <p> |
|
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parents:
diff
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|
3847 Pushes a nil value onto the stack. |
|
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parents:
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|
3848 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3849 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3850 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3851 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
3852 |
|
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|
3853 <hr><h3><a name="lua_pushnumber"><code>lua_pushnumber</code></a></h3><p> |
|
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|
3854 <span class="apii">[-0, +1, –]</span> |
|
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parents:
diff
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|
3855 <pre>void lua_pushnumber (lua_State *L, lua_Number n);</pre> |
|
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|
3856 |
|
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diff
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|
3857 <p> |
|
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diff
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|
3858 Pushes a float with value <code>n</code> onto the stack. |
|
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parents:
diff
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|
3859 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3860 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3861 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3862 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3863 |
|
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parents:
diff
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|
3864 <hr><h3><a name="lua_pushstring"><code>lua_pushstring</code></a></h3><p> |
|
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|
3865 <span class="apii">[-0, +1, <em>e</em>]</span> |
|
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parents:
diff
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|
3866 <pre>const char *lua_pushstring (lua_State *L, const char *s);</pre> |
|
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|
3867 |
|
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diff
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|
3868 <p> |
|
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parents:
diff
changeset
|
3869 Pushes the zero-terminated string pointed to by <code>s</code> |
|
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parents:
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|
3870 onto the stack. |
|
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parents:
diff
changeset
|
3871 Lua makes (or reuses) an internal copy of the given string, |
|
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parents:
diff
changeset
|
3872 so the memory at <code>s</code> can be freed or reused immediately after |
|
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parents:
diff
changeset
|
3873 the function returns. |
|
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parents:
diff
changeset
|
3874 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3875 |
|
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diff
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|
3876 <p> |
|
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parents:
diff
changeset
|
3877 Returns a pointer to the internal copy of the string. |
|
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parents:
diff
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|
3878 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3879 |
|
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diff
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|
3880 <p> |
|
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|
3881 If <code>s</code> is <code>NULL</code>, pushes <b>nil</b> and returns <code>NULL</code>. |
|
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|
3882 |
|
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diff
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|
3883 |
|
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diff
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|
3884 |
|
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diff
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|
3885 |
|
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|
3886 |
|
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|
3887 <hr><h3><a name="lua_pushthread"><code>lua_pushthread</code></a></h3><p> |
|
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|
3888 <span class="apii">[-0, +1, –]</span> |
|
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|
3889 <pre>int lua_pushthread (lua_State *L);</pre> |
|
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|
3890 |
|
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|
3891 <p> |
|
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changeset
|
3892 Pushes the thread represented by <code>L</code> onto the stack. |
|
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|
3893 Returns 1 if this thread is the main thread of its state. |
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|
3894 |
|
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|
3895 |
|
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|
3896 |
|
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|
3897 |
|
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|
3898 |
|
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|
3899 <hr><h3><a name="lua_pushvalue"><code>lua_pushvalue</code></a></h3><p> |
|
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|
3900 <span class="apii">[-0, +1, –]</span> |
|
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|
3901 <pre>void lua_pushvalue (lua_State *L, int index);</pre> |
|
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|
3902 |
|
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|
3903 <p> |
|
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|
3904 Pushes a copy of the element at the given index |
|
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|
3905 onto the stack. |
|
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|
3906 |
|
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|
3907 |
|
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|
3908 |
|
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|
3909 |
|
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|
3910 |
|
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|
3911 <hr><h3><a name="lua_pushvfstring"><code>lua_pushvfstring</code></a></h3><p> |
|
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|
3912 <span class="apii">[-0, +1, <em>e</em>]</span> |
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|
3913 <pre>const char *lua_pushvfstring (lua_State *L, |
|
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|
3914 const char *fmt, |
|
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|
3915 va_list argp);</pre> |
|
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|
3916 |
|
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diff
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|
3917 <p> |
|
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|
3918 Equivalent to <a href="#lua_pushfstring"><code>lua_pushfstring</code></a>, except that it receives a <code>va_list</code> |
|
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|
3919 instead of a variable number of arguments. |
|
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|
3920 |
|
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|
3921 |
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|
3922 |
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|
3923 |
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|
3924 |
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|
3925 <hr><h3><a name="lua_rawequal"><code>lua_rawequal</code></a></h3><p> |
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|
3926 <span class="apii">[-0, +0, –]</span> |
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|
3927 <pre>int lua_rawequal (lua_State *L, int index1, int index2);</pre> |
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|
3928 |
|
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|
3929 <p> |
|
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|
3930 Returns 1 if the two values in indices <code>index1</code> and |
|
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|
3931 <code>index2</code> are primitively equal |
|
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|
3932 (that is, without calling metamethods). |
|
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|
3933 Otherwise returns 0. |
|
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|
3934 Also returns 0 if any of the indices are not valid. |
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|
3935 |
|
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|
3936 |
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|
3937 |
|
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changeset
|
3938 |
|
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diff
changeset
|
3939 |
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|
3940 <hr><h3><a name="lua_rawget"><code>lua_rawget</code></a></h3><p> |
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|
3941 <span class="apii">[-1, +1, –]</span> |
|
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|
3942 <pre>int lua_rawget (lua_State *L, int index);</pre> |
|
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|
3943 |
|
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|
3944 <p> |
|
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|
3945 Similar to <a href="#lua_gettable"><code>lua_gettable</code></a>, but does a raw access |
|
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|
3946 (i.e., without metamethods). |
|
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|
3947 |
|
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diff
changeset
|
3948 |
|
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diff
changeset
|
3949 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3950 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3951 |
|
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|
3952 <hr><h3><a name="lua_rawgeti"><code>lua_rawgeti</code></a></h3><p> |
|
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|
3953 <span class="apii">[-0, +1, –]</span> |
|
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|
3954 <pre>int lua_rawgeti (lua_State *L, int index, lua_Integer n);</pre> |
|
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|
3955 |
|
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|
3956 <p> |
|
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|
3957 Pushes onto the stack the value <code>t[n]</code>, |
|
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|
3958 where <code>t</code> is the table at the given index. |
|
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|
3959 The access is raw; |
|
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|
3960 that is, it does not invoke metamethods. |
|
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|
3961 |
|
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diff
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|
3962 |
|
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|
3963 <p> |
|
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|
3964 Returns the type of the pushed value. |
|
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|
3965 |
|
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|
3966 |
|
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|
3967 |
|
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diff
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|
3968 |
|
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|
3969 |
|
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|
3970 <hr><h3><a name="lua_rawgetp"><code>lua_rawgetp</code></a></h3><p> |
|
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|
3971 <span class="apii">[-0, +1, –]</span> |
|
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|
3972 <pre>int lua_rawgetp (lua_State *L, int index, const void *p);</pre> |
|
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|
3973 |
|
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|
3974 <p> |
|
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|
3975 Pushes onto the stack the value <code>t[k]</code>, |
|
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|
3976 where <code>t</code> is the table at the given index and |
|
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|
3977 <code>k</code> is the pointer <code>p</code> represented as a light userdata. |
|
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|
3978 The access is raw; |
|
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|
3979 that is, it does not invoke metamethods. |
|
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|
3980 |
|
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diff
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|
3981 |
|
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|
3982 <p> |
|
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|
3983 Returns the type of the pushed value. |
|
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diff
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|
3984 |
|
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parents:
diff
changeset
|
3985 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3986 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3987 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3988 |
|
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|
3989 <hr><h3><a name="lua_rawlen"><code>lua_rawlen</code></a></h3><p> |
|
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|
3990 <span class="apii">[-0, +0, –]</span> |
|
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|
3991 <pre>size_t lua_rawlen (lua_State *L, int index);</pre> |
|
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|
3992 |
|
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|
3993 <p> |
|
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|
3994 Returns the raw "length" of the value at the given index: |
|
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|
3995 for strings, this is the string length; |
|
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parents:
diff
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|
3996 for tables, this is the result of the length operator ('<code>#</code>') |
|
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parents:
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|
3997 with no metamethods; |
|
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|
3998 for userdata, this is the size of the block of memory allocated |
|
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|
3999 for the userdata; |
|
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|
4000 for other values, it is 0. |
|
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|
4001 |
|
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|
4002 |
|
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|
4003 |
|
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|
4004 |
|
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|
4005 |
|
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|
4006 <hr><h3><a name="lua_rawset"><code>lua_rawset</code></a></h3><p> |
|
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|
4007 <span class="apii">[-2, +0, <em>e</em>]</span> |
|
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|
4008 <pre>void lua_rawset (lua_State *L, int index);</pre> |
|
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|
4009 |
|
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|
4010 <p> |
|
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|
4011 Similar to <a href="#lua_settable"><code>lua_settable</code></a>, but does a raw assignment |
|
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|
4012 (i.e., without metamethods). |
|
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|
4013 |
|
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changeset
|
4014 |
|
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|
4015 |
|
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|
4016 |
|
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|
4017 |
|
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|
4018 <hr><h3><a name="lua_rawseti"><code>lua_rawseti</code></a></h3><p> |
|
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|
4019 <span class="apii">[-1, +0, <em>e</em>]</span> |
|
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|
4020 <pre>void lua_rawseti (lua_State *L, int index, lua_Integer i);</pre> |
|
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|
4021 |
|
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|
4022 <p> |
|
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|
4023 Does the equivalent of <code>t[i] = v</code>, |
|
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|
4024 where <code>t</code> is the table at the given index |
|
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|
4025 and <code>v</code> is the value at the top of the stack. |
|
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changeset
|
4026 |
|
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changeset
|
4027 |
|
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|
4028 <p> |
|
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|
4029 This function pops the value from the stack. |
|
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|
4030 The assignment is raw; |
|
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|
4031 that is, it does not invoke metamethods. |
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|
4032 |
|
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|
4033 |
|
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|
4034 |
|
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|
4035 |
|
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|
4036 |
|
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|
4037 <hr><h3><a name="lua_rawsetp"><code>lua_rawsetp</code></a></h3><p> |
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4038 <span class="apii">[-1, +0, <em>e</em>]</span> |
|
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|
4039 <pre>void lua_rawsetp (lua_State *L, int index, const void *p);</pre> |
|
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|
4040 |
|
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|
4041 <p> |
|
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|
4042 Does the equivalent of <code>t[k] = v</code>, |
|
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|
4043 where <code>t</code> is the table at the given index, |
|
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|
4044 <code>k</code> is the pointer <code>p</code> represented as a light userdata, |
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|
4045 and <code>v</code> is the value at the top of the stack. |
|
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|
4046 |
|
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|
4047 |
|
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|
4048 <p> |
|
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|
4049 This function pops the value from the stack. |
|
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parents:
diff
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|
4050 The assignment is raw; |
|
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diff
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|
4051 that is, it does not invoke metamethods. |
|
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|
4052 |
|
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diff
changeset
|
4053 |
|
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diff
changeset
|
4054 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
4055 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
4056 |
|
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|
4057 <hr><h3><a name="lua_Reader"><code>lua_Reader</code></a></h3> |
|
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|
4058 <pre>typedef const char * (*lua_Reader) (lua_State *L, |
|
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|
4059 void *data, |
|
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|
4060 size_t *size);</pre> |
|
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|
4061 |
|
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|
4062 <p> |
|
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|
4063 The reader function used by <a href="#lua_load"><code>lua_load</code></a>. |
|
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|
4064 Every time it needs another piece of the chunk, |
|
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diff
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|
4065 <a href="#lua_load"><code>lua_load</code></a> calls the reader, |
|
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|
4066 passing along its <code>data</code> parameter. |
|
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|
4067 The reader must return a pointer to a block of memory |
|
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|
4068 with a new piece of the chunk |
|
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|
4069 and set <code>size</code> to the block size. |
|
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|
4070 The block must exist until the reader function is called again. |
|
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|
4071 To signal the end of the chunk, |
|
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|
4072 the reader must return <code>NULL</code> or set <code>size</code> to zero. |
|
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|
4073 The reader function may return pieces of any size greater than zero. |
|
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|
4074 |
|
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diff
changeset
|
4075 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
4076 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
4077 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
4078 |
|
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|
4079 <hr><h3><a name="lua_register"><code>lua_register</code></a></h3><p> |
|
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|
4080 <span class="apii">[-0, +0, <em>e</em>]</span> |
|
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|
4081 <pre>void lua_register (lua_State *L, const char *name, lua_CFunction f);</pre> |
|
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|
4082 |
|
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|
4083 <p> |
|
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|
4084 Sets the C function <code>f</code> as the new value of global <code>name</code>. |
|
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|
4085 It is defined as a macro: |
|
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|
4086 |
|
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|
4087 <pre> |
|
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|
4088 #define lua_register(L,n,f) \ |
|
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|
4089 (lua_pushcfunction(L, f), lua_setglobal(L, n)) |
|
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|
4090 </pre> |
|
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|
4091 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
4092 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
4093 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
4094 |
|
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|
4095 <hr><h3><a name="lua_remove"><code>lua_remove</code></a></h3><p> |
|
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|
4096 <span class="apii">[-1, +0, –]</span> |
|
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|
4097 <pre>void lua_remove (lua_State *L, int index);</pre> |
|
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|
4098 |
|
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|
4099 <p> |
|
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|
4100 Removes the element at the given valid index, |
|
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|
4101 shifting down the elements above this index to fill the gap. |
|
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|
4102 This function cannot be called with a pseudo-index, |
|
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|
4103 because a pseudo-index is not an actual stack position. |
|
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|
4104 |
|
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changeset
|
4105 |
|
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|
4106 |
|
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diff
changeset
|
4107 |
|
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|
4108 |
|
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|
4109 <hr><h3><a name="lua_replace"><code>lua_replace</code></a></h3><p> |
|
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4110 <span class="apii">[-1, +0, –]</span> |
|
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|
4111 <pre>void lua_replace (lua_State *L, int index);</pre> |
|
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|
4112 |
|
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|
4113 <p> |
|
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|
4114 Moves the top element into the given valid index |
|
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|
4115 without shifting any element |
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|
4116 (therefore replacing the value at the given index), |
|
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|
4117 and then pops the top element. |
|
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|
4118 |
|
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|
4119 |
|
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|
4120 |
|
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|
4121 |
|
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|
4122 |
|
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|
4123 <hr><h3><a name="lua_resume"><code>lua_resume</code></a></h3><p> |
|
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4124 <span class="apii">[-?, +?, –]</span> |
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|
4125 <pre>int lua_resume (lua_State *L, lua_State *from, int nargs);</pre> |
|
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|
4126 |
|
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|
4127 <p> |
|
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|
4128 Starts and resumes a coroutine in a given thread. |
|
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|
4129 |
|
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|
4130 |
|
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|
4131 <p> |
|
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|
4132 To start a coroutine, |
|
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|
4133 you push onto the thread stack the main function plus any arguments; |
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|
4134 then you call <a href="#lua_resume"><code>lua_resume</code></a>, |
|
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|
4135 with <code>nargs</code> being the number of arguments. |
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|
4136 This call returns when the coroutine suspends or finishes its execution. |
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|
4137 When it returns, the stack contains all values passed to <a href="#lua_yield"><code>lua_yield</code></a>, |
|
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|
4138 or all values returned by the body function. |
|
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|
4139 <a href="#lua_resume"><code>lua_resume</code></a> returns |
|
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|
4140 <a href="#pdf-LUA_YIELD"><code>LUA_YIELD</code></a> if the coroutine yields, |
|
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|
4141 <a href="#pdf-LUA_OK"><code>LUA_OK</code></a> if the coroutine finishes its execution |
|
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4142 without errors, |
|
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changeset
|
4143 or an error code in case of errors (see <a href="#lua_pcall"><code>lua_pcall</code></a>). |
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4144 |
|
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|
4145 |
|
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|
4146 <p> |
|
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|
4147 In case of errors, |
|
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|
4148 the stack is not unwound, |
|
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|
4149 so you can use the debug API over it. |
|
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4150 The error message is on the top of the stack. |
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4151 |
|
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4152 |
|
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|
4153 <p> |
|
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|
4154 To resume a coroutine, |
|
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|
4155 you remove any results from the last <a href="#lua_yield"><code>lua_yield</code></a>, |
|
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4156 put on its stack only the values to |
|
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|
4157 be passed as results from <code>yield</code>, |
|
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|
4158 and then call <a href="#lua_resume"><code>lua_resume</code></a>. |
|
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|
4159 |
|
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|
4160 |
|
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|
4161 <p> |
|
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|
4162 The parameter <code>from</code> represents the coroutine that is resuming <code>L</code>. |
|
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4163 If there is no such coroutine, |
|
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|
4164 this parameter can be <code>NULL</code>. |
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|
4165 |
|
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4166 |
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4167 |
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|
4168 |
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|
4169 |
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|
4170 <hr><h3><a name="lua_rotate"><code>lua_rotate</code></a></h3><p> |
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4171 <span class="apii">[-0, +0, –]</span> |
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|
4172 <pre>void lua_rotate (lua_State *L, int idx, int n);</pre> |
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4173 |
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4174 <p> |
|
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|
4175 Rotates the stack elements from <code>idx</code> to the top <code>n</code> positions |
|
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|
4176 in the direction of the top, for a positive <code>n</code>, |
|
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|
4177 or <code>-n</code> positions in the direction of the bottom, |
|
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|
4178 for a negative <code>n</code>. |
|
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|
4179 The absolute value of <code>n</code> must not be greater than the size |
|
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|
4180 of the slice being rotated. |
|
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|
4181 |
|
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|
4182 |
|
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|
4183 |
|
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|
4184 |
|
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|
4185 |
|
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|
4186 <hr><h3><a name="lua_setallocf"><code>lua_setallocf</code></a></h3><p> |
|
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4187 <span class="apii">[-0, +0, –]</span> |
|
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|
4188 <pre>void lua_setallocf (lua_State *L, lua_Alloc f, void *ud);</pre> |
|
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|
4189 |
|
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|
4190 <p> |
|
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|
4191 Changes the allocator function of a given state to <code>f</code> |
|
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|
4192 with user data <code>ud</code>. |
|
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|
4193 |
|
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|
4194 |
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|
4195 |
|
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|
4196 |
|
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|
4197 |
|
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|
4198 <hr><h3><a name="lua_setfield"><code>lua_setfield</code></a></h3><p> |
|
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|
4199 <span class="apii">[-1, +0, <em>e</em>]</span> |
|
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|
4200 <pre>void lua_setfield (lua_State *L, int index, const char *k);</pre> |
|
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|
4201 |
|
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|
4202 <p> |
|
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|
4203 Does the equivalent to <code>t[k] = v</code>, |
|
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diff
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|
4204 where <code>t</code> is the value at the given index |
|
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|
4205 and <code>v</code> is the value at the top of the stack. |
|
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|
4206 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
4207 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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|
4208 <p> |
|
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|
4209 This function pops the value from the stack. |
|
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|
4210 As in Lua, this function may trigger a metamethod |
|
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diff
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|
4211 for the "newindex" event (see <a href="#2.4">§2.4</a>). |
|
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parents:
diff
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|
4212 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
4213 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
4214 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
4215 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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|
4216 |
|
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|
4217 <hr><h3><a name="lua_setglobal"><code>lua_setglobal</code></a></h3><p> |
|
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|
4218 <span class="apii">[-1, +0, <em>e</em>]</span> |
|
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parents:
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|
4219 <pre>void lua_setglobal (lua_State *L, const char *name);</pre> |
|
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|
4220 |
|
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diff
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|
4221 <p> |
|
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|
4222 Pops a value from the stack and |
|
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parents:
diff
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|
4223 sets it as the new value of global <code>name</code>. |
|
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parents:
diff
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|
4224 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
4225 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
4226 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
4227 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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changeset
|
4228 |
|
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|
4229 <hr><h3><a name="lua_seti"><code>lua_seti</code></a></h3><p> |
|
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|
4230 <span class="apii">[-1, +0, <em>e</em>]</span> |
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|
4231 <pre>void lua_seti (lua_State *L, int index, lua_Integer n);</pre> |
|
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|
4232 |
|
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|
4233 <p> |
|
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|
4234 Does the equivalent to <code>t[n] = v</code>, |
|
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|
4235 where <code>t</code> is the value at the given index |
|
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|
4236 and <code>v</code> is the value at the top of the stack. |
|
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|
4237 |
|
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|
4238 |
|
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|
4239 <p> |
|
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|
4240 This function pops the value from the stack. |
|
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|
4241 As in Lua, this function may trigger a metamethod |
|
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|
4242 for the "newindex" event (see <a href="#2.4">§2.4</a>). |
|
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|
4243 |
|
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changeset
|
4244 |
|
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changeset
|
4245 |
|
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changeset
|
4246 |
|
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|
4247 |
|
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|
4248 <hr><h3><a name="lua_setmetatable"><code>lua_setmetatable</code></a></h3><p> |
|
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|
4249 <span class="apii">[-1, +0, –]</span> |
|
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|
4250 <pre>void lua_setmetatable (lua_State *L, int index);</pre> |
|
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|
4251 |
|
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|
4252 <p> |
|
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|
4253 Pops a table from the stack and |
|
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|
4254 sets it as the new metatable for the value at the given index. |
|
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|
4255 |
|
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changeset
|
4256 |
|
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changeset
|
4257 |
|
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|
4258 |
|
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|
4259 |
|
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|
4260 <hr><h3><a name="lua_settable"><code>lua_settable</code></a></h3><p> |
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|
4261 <span class="apii">[-2, +0, <em>e</em>]</span> |
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|
4262 <pre>void lua_settable (lua_State *L, int index);</pre> |
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4263 |
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|
4264 <p> |
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|
4265 Does the equivalent to <code>t[k] = v</code>, |
|
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|
4266 where <code>t</code> is the value at the given index, |
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|
4267 <code>v</code> is the value at the top of the stack, |
|
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|
4268 and <code>k</code> is the value just below the top. |
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|
4269 |
|
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|
4270 |
|
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|
4271 <p> |
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|
4272 This function pops both the key and the value from the stack. |
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|
4273 As in Lua, this function may trigger a metamethod |
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|
4274 for the "newindex" event (see <a href="#2.4">§2.4</a>). |
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|
4275 |
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|
4276 |
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|
4277 |
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|
4278 |
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4279 |
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4280 <hr><h3><a name="lua_settop"><code>lua_settop</code></a></h3><p> |
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|
4281 <span class="apii">[-?, +?, –]</span> |
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|
4282 <pre>void lua_settop (lua_State *L, int index);</pre> |
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4283 |
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4284 <p> |
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|
4285 Accepts any index, or 0, |
|
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4286 and sets the stack top to this index. |
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|
4287 If the new top is larger than the old one, |
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|
4288 then the new elements are filled with <b>nil</b>. |
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|
4289 If <code>index</code> is 0, then all stack elements are removed. |
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|
4290 |
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|
4291 |
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|
4292 |
|
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|
4293 |
|
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|
4294 |
|
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|
4295 <hr><h3><a name="lua_setuservalue"><code>lua_setuservalue</code></a></h3><p> |
|
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|
4296 <span class="apii">[-1, +0, –]</span> |
|
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|
4297 <pre>void lua_setuservalue (lua_State *L, int index);</pre> |
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4298 |
|
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|
4299 <p> |
|
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|
4300 Pops a value from the stack and sets it as |
|
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|
4301 the new value associated to the userdata at the given index. |
|
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|
4302 |
|
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|
4303 |
|
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|
4304 |
|
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|
4305 |
|
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|
4306 |
|
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|
4307 <hr><h3><a name="lua_State"><code>lua_State</code></a></h3> |
|
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|
4308 <pre>typedef struct lua_State lua_State;</pre> |
|
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|
4309 |
|
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|
4310 <p> |
|
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|
4311 An opaque structure that points to a thread and indirectly |
|
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|
4312 (through the thread) to the whole state of a Lua interpreter. |
|
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|
4313 The Lua library is fully reentrant: |
|
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|
4314 it has no global variables. |
|
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|
4315 All information about a state is accessible through this structure. |
|
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|
4316 |
|
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|
4317 |
|
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|
4318 <p> |
|
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|
4319 A pointer to this structure must be passed as the first argument to |
|
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|
4320 every function in the library, except to <a href="#lua_newstate"><code>lua_newstate</code></a>, |
|
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|
4321 which creates a Lua state from scratch. |
|
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|
4322 |
|
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|
4323 |
|
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|
4324 |
|
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|
4325 |
|
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|
4326 |
|
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|
4327 <hr><h3><a name="lua_status"><code>lua_status</code></a></h3><p> |
|
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|
4328 <span class="apii">[-0, +0, –]</span> |
|
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|
4329 <pre>int lua_status (lua_State *L);</pre> |
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|
4330 |
|
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|
4331 <p> |
|
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|
4332 Returns the status of the thread <code>L</code>. |
|
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|
4333 |
|
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|
4334 |
|
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|
4335 <p> |
|
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|
4336 The status can be 0 (<a href="#pdf-LUA_OK"><code>LUA_OK</code></a>) for a normal thread, |
|
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|
4337 an error code if the thread finished the execution |
|
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|
4338 of a <a href="#lua_resume"><code>lua_resume</code></a> with an error, |
|
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|
4339 or <a name="pdf-LUA_YIELD"><code>LUA_YIELD</code></a> if the thread is suspended. |
|
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|
4340 |
|
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|
4341 |
|
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|
4342 <p> |
|
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|
4343 You can only call functions in threads with status <a href="#pdf-LUA_OK"><code>LUA_OK</code></a>. |
|
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|
4344 You can resume threads with status <a href="#pdf-LUA_OK"><code>LUA_OK</code></a> |
|
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|
4345 (to start a new coroutine) or <a href="#pdf-LUA_YIELD"><code>LUA_YIELD</code></a> |
|
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|
4346 (to resume a coroutine). |
|
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|
4347 |
|
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|
4348 |
|
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|
4349 |
|
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|
4350 |
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|
4351 |
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|
4352 <hr><h3><a name="lua_stringtonumber"><code>lua_stringtonumber</code></a></h3><p> |
|
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4353 <span class="apii">[-0, +1, –]</span> |
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|
4354 <pre>size_t lua_stringtonumber (lua_State *L, const char *s);</pre> |
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4355 |
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|
4356 <p> |
|
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|
4357 Converts the zero-terminated string <code>s</code> to a number, |
|
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4358 pushes that number into the stack, |
|
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|
4359 and returns the total size of the string, |
|
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|
4360 that is, its length plus one. |
|
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4361 The conversion can result in an integer or a float, |
|
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4362 according to the lexical conventions of Lua (see <a href="#3.1">§3.1</a>). |
|
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4363 The string may have leading and trailing spaces and a sign. |
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4364 If the string is not a valid numeral, |
|
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4365 returns 0 and pushes nothing. |
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|
4366 (Note that the result can be used as a boolean, |
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|
4367 true if the conversion succeeds.) |
|
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|
4368 |
|
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|
4369 |
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|
4370 |
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|
4371 |
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|
4372 |
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|
4373 <hr><h3><a name="lua_toboolean"><code>lua_toboolean</code></a></h3><p> |
|
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4374 <span class="apii">[-0, +0, –]</span> |
|
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|
4375 <pre>int lua_toboolean (lua_State *L, int index);</pre> |
|
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4376 |
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|
4377 <p> |
|
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|
4378 Converts the Lua value at the given index to a C boolean |
|
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|
4379 value (0 or 1). |
|
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|
4380 Like all tests in Lua, |
|
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|
4381 <a href="#lua_toboolean"><code>lua_toboolean</code></a> returns true for any Lua value |
|
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4382 different from <b>false</b> and <b>nil</b>; |
|
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4383 otherwise it returns false. |
|
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|
4384 (If you want to accept only actual boolean values, |
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|
4385 use <a href="#lua_isboolean"><code>lua_isboolean</code></a> to test the value's type.) |
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4386 |
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4387 |
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|
4388 |
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4389 |
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4390 |
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4391 <hr><h3><a name="lua_tocfunction"><code>lua_tocfunction</code></a></h3><p> |
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4392 <span class="apii">[-0, +0, –]</span> |
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4393 <pre>lua_CFunction lua_tocfunction (lua_State *L, int index);</pre> |
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4394 |
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4395 <p> |
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4396 Converts a value at the given index to a C function. |
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4397 That value must be a C function; |
|
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4398 otherwise, returns <code>NULL</code>. |
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4399 |
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4400 |
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4401 |
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4402 |
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4403 |
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|
4404 <hr><h3><a name="lua_tointeger"><code>lua_tointeger</code></a></h3><p> |
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4405 <span class="apii">[-0, +0, –]</span> |
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|
4406 <pre>lua_Integer lua_tointeger (lua_State *L, int index);</pre> |
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4407 |
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|
4408 <p> |
|
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|
4409 Equivalent to <a href="#lua_tointegerx"><code>lua_tointegerx</code></a> with <code>isnum</code> equal to <code>NULL</code>. |
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|
4410 |
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|
4411 |
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|
4412 |
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|
4413 |
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|
4414 |
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|
4415 <hr><h3><a name="lua_tointegerx"><code>lua_tointegerx</code></a></h3><p> |
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|
4416 <span class="apii">[-0, +0, –]</span> |
|
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|
4417 <pre>lua_Integer lua_tointegerx (lua_State *L, int index, int *isnum);</pre> |
|
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|
4418 |
|
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|
4419 <p> |
|
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|
4420 Converts the Lua value at the given index |
|
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|
4421 to the signed integral type <a href="#lua_Integer"><code>lua_Integer</code></a>. |
|
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|
4422 The Lua value must be an integer, |
|
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|
4423 or a number or string convertible to an integer (see <a href="#3.4.3">§3.4.3</a>); |
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|
4424 otherwise, <code>lua_tointegerx</code> returns 0. |
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|
4425 |
|
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|
4426 |
|
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|
4427 <p> |
|
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|
4428 If <code>isnum</code> is not <code>NULL</code>, |
|
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|
4429 its referent is assigned a boolean value that |
|
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|
4430 indicates whether the operation succeeded. |
|
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|
4431 |
|
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|
4432 |
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|
4433 |
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|
4434 |
|
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|
4435 |
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|
4436 <hr><h3><a name="lua_tolstring"><code>lua_tolstring</code></a></h3><p> |
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|
4437 <span class="apii">[-0, +0, <em>e</em>]</span> |
|
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|
4438 <pre>const char *lua_tolstring (lua_State *L, int index, size_t *len);</pre> |
|
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|
4439 |
|
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|
4440 <p> |
|
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|
4441 Converts the Lua value at the given index to a C string. |
|
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|
4442 If <code>len</code> is not <code>NULL</code>, |
|
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|
4443 it also sets <code>*len</code> with the string length. |
|
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|
4444 The Lua value must be a string or a number; |
|
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|
4445 otherwise, the function returns <code>NULL</code>. |
|
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|
4446 If the value is a number, |
|
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|
4447 then <code>lua_tolstring</code> also |
|
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|
4448 <em>changes the actual value in the stack to a string</em>. |
|
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|
4449 (This change confuses <a href="#lua_next"><code>lua_next</code></a> |
|
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|
4450 when <code>lua_tolstring</code> is applied to keys during a table traversal.) |
|
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|
4451 |
|
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|
4452 |
|
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|
4453 <p> |
|
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|
4454 <code>lua_tolstring</code> returns a fully aligned pointer |
|
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|
4455 to a string inside the Lua state. |
|
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|
4456 This string always has a zero ('<code>\0</code>') |
|
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|
4457 after its last character (as in C), |
|
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|
4458 but can contain other zeros in its body. |
|
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|
4459 |
|
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|
4460 |
|
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|
4461 <p> |
|
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|
4462 Because Lua has garbage collection, |
|
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|
4463 there is no guarantee that the pointer returned by <code>lua_tolstring</code> |
|
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|
4464 will be valid after the corresponding Lua value is removed from the stack. |
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|
4465 |
|
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|
4466 |
|
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|
4467 |
|
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|
4468 |
|
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|
4469 |
|
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|
4470 <hr><h3><a name="lua_tonumber"><code>lua_tonumber</code></a></h3><p> |
|
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|
4471 <span class="apii">[-0, +0, –]</span> |
|
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|
4472 <pre>lua_Number lua_tonumber (lua_State *L, int index);</pre> |
|
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|
4473 |
|
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|
4474 <p> |
|
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|
4475 Equivalent to <a href="#lua_tonumberx"><code>lua_tonumberx</code></a> with <code>isnum</code> equal to <code>NULL</code>. |
|
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|
4476 |
|
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|
4477 |
|
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|
4478 |
|
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|
4479 |
|
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|
4480 |
|
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|
4481 <hr><h3><a name="lua_tonumberx"><code>lua_tonumberx</code></a></h3><p> |
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|
4482 <span class="apii">[-0, +0, –]</span> |
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|
4483 <pre>lua_Number lua_tonumberx (lua_State *L, int index, int *isnum);</pre> |
|
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|
4484 |
|
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|
4485 <p> |
|
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|
4486 Converts the Lua value at the given index |
|
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|
4487 to the C type <a href="#lua_Number"><code>lua_Number</code></a> (see <a href="#lua_Number"><code>lua_Number</code></a>). |
|
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4488 The Lua value must be a number or a string convertible to a number |
|
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|
4489 (see <a href="#3.4.3">§3.4.3</a>); |
|
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|
4490 otherwise, <a href="#lua_tonumberx"><code>lua_tonumberx</code></a> returns 0. |
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4491 |
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4492 |
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|
4493 <p> |
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|
4494 If <code>isnum</code> is not <code>NULL</code>, |
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4495 its referent is assigned a boolean value that |
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|
4496 indicates whether the operation succeeded. |
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4497 |
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4498 |
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4499 |
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4500 |
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4501 |
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4502 <hr><h3><a name="lua_topointer"><code>lua_topointer</code></a></h3><p> |
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4503 <span class="apii">[-0, +0, –]</span> |
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|
4504 <pre>const void *lua_topointer (lua_State *L, int index);</pre> |
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4505 |
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4506 <p> |
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4507 Converts the value at the given index to a generic |
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4508 C pointer (<code>void*</code>). |
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4509 The value can be a userdata, a table, a thread, or a function; |
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4510 otherwise, <code>lua_topointer</code> returns <code>NULL</code>. |
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4511 Different objects will give different pointers. |
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4512 There is no way to convert the pointer back to its original value. |
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4513 |
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4514 |
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4515 <p> |
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4516 Typically this function is used only for debug information. |
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4517 |
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4518 |
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4519 |
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4520 |
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4521 |
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4522 <hr><h3><a name="lua_tostring"><code>lua_tostring</code></a></h3><p> |
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4523 <span class="apii">[-0, +0, <em>e</em>]</span> |
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4524 <pre>const char *lua_tostring (lua_State *L, int index);</pre> |
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4525 |
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4526 <p> |
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|
4527 Equivalent to <a href="#lua_tolstring"><code>lua_tolstring</code></a> with <code>len</code> equal to <code>NULL</code>. |
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4528 |
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|
4529 |
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|
4530 |
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4531 |
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4532 |
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4533 <hr><h3><a name="lua_tothread"><code>lua_tothread</code></a></h3><p> |
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|
4534 <span class="apii">[-0, +0, –]</span> |
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|
4535 <pre>lua_State *lua_tothread (lua_State *L, int index);</pre> |
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4536 |
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|
4537 <p> |
|
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|
4538 Converts the value at the given index to a Lua thread |
|
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|
4539 (represented as <code>lua_State*</code>). |
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|
4540 This value must be a thread; |
|
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|
4541 otherwise, the function returns <code>NULL</code>. |
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4542 |
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|
4543 |
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|
4544 |
|
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|
4545 |
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|
4546 |
|
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|
4547 <hr><h3><a name="lua_touserdata"><code>lua_touserdata</code></a></h3><p> |
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|
4548 <span class="apii">[-0, +0, –]</span> |
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|
4549 <pre>void *lua_touserdata (lua_State *L, int index);</pre> |
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|
4550 |
|
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|
4551 <p> |
|
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|
4552 If the value at the given index is a full userdata, |
|
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|
4553 returns its block address. |
|
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|
4554 If the value is a light userdata, |
|
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|
4555 returns its pointer. |
|
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|
4556 Otherwise, returns <code>NULL</code>. |
|
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|
4557 |
|
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|
4558 |
|
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|
4559 |
|
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|
4560 |
|
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|
4561 |
|
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|
4562 <hr><h3><a name="lua_type"><code>lua_type</code></a></h3><p> |
|
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4563 <span class="apii">[-0, +0, –]</span> |
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|
4564 <pre>int lua_type (lua_State *L, int index);</pre> |
|
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|
4565 |
|
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|
4566 <p> |
|
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|
4567 Returns the type of the value in the given valid index, |
|
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|
4568 or <code>LUA_TNONE</code> for a non-valid (but acceptable) index. |
|
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|
4569 The types returned by <a href="#lua_type"><code>lua_type</code></a> are coded by the following constants |
|
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|
4570 defined in <code>lua.h</code>: |
|
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|
4571 <a name="pdf-LUA_TNIL"><code>LUA_TNIL</code></a>, |
|
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|
4572 <a name="pdf-LUA_TNUMBER"><code>LUA_TNUMBER</code></a>, |
|
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|
4573 <a name="pdf-LUA_TBOOLEAN"><code>LUA_TBOOLEAN</code></a>, |
|
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|
4574 <a name="pdf-LUA_TSTRING"><code>LUA_TSTRING</code></a>, |
|
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|
4575 <a name="pdf-LUA_TTABLE"><code>LUA_TTABLE</code></a>, |
|
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|
4576 <a name="pdf-LUA_TFUNCTION"><code>LUA_TFUNCTION</code></a>, |
|
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|
4577 <a name="pdf-LUA_TUSERDATA"><code>LUA_TUSERDATA</code></a>, |
|
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|
4578 <a name="pdf-LUA_TTHREAD"><code>LUA_TTHREAD</code></a>, |
|
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|
4579 and |
|
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|
4580 <a name="pdf-LUA_TLIGHTUSERDATA"><code>LUA_TLIGHTUSERDATA</code></a>. |
|
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|
4581 |
|
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|
4582 |
|
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|
4583 |
|
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|
4584 |
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|
4585 |
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|
4586 <hr><h3><a name="lua_typename"><code>lua_typename</code></a></h3><p> |
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4587 <span class="apii">[-0, +0, –]</span> |
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|
4588 <pre>const char *lua_typename (lua_State *L, int tp);</pre> |
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|
4589 |
|
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|
4590 <p> |
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|
4591 Returns the name of the type encoded by the value <code>tp</code>, |
|
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|
4592 which must be one the values returned by <a href="#lua_type"><code>lua_type</code></a>. |
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|
4593 |
|
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|
4594 |
|
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|
4595 |
|
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|
4596 |
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|
4597 |
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|
4598 <hr><h3><a name="lua_Unsigned"><code>lua_Unsigned</code></a></h3> |
|
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|
4599 <pre>typedef ... lua_Unsigned;</pre> |
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4600 |
|
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|
4601 <p> |
|
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|
4602 The unsigned version of <a href="#lua_Integer"><code>lua_Integer</code></a>. |
|
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4603 |
|
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|
4604 |
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|
4605 |
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4606 |
|
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4607 |
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4608 <hr><h3><a name="lua_upvalueindex"><code>lua_upvalueindex</code></a></h3><p> |
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4609 <span class="apii">[-0, +0, –]</span> |
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4610 <pre>int lua_upvalueindex (int i);</pre> |
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4611 |
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4612 <p> |
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4613 Returns the pseudo-index that represents the <code>i</code>-th upvalue of |
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4614 the running function (see <a href="#4.4">§4.4</a>). |
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4615 |
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4616 |
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4617 |
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4618 |
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4619 |
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4620 <hr><h3><a name="lua_version"><code>lua_version</code></a></h3><p> |
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4621 <span class="apii">[-0, +0, <em>v</em>]</span> |
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4622 <pre>const lua_Number *lua_version (lua_State *L);</pre> |
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4623 |
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4624 <p> |
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4625 Returns the address of the version number stored in the Lua core. |
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4626 When called with a valid <a href="#lua_State"><code>lua_State</code></a>, |
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4627 returns the address of the version used to create that state. |
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4628 When called with <code>NULL</code>, |
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4629 returns the address of the version running the call. |
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4630 |
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4631 |
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4632 |
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4633 |
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4634 |
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4635 <hr><h3><a name="lua_Writer"><code>lua_Writer</code></a></h3> |
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4636 <pre>typedef int (*lua_Writer) (lua_State *L, |
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4637 const void* p, |
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4638 size_t sz, |
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|
4639 void* ud);</pre> |
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4640 |
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4641 <p> |
|
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|
4642 The type of the writer function used by <a href="#lua_dump"><code>lua_dump</code></a>. |
|
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4643 Every time it produces another piece of chunk, |
|
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|
4644 <a href="#lua_dump"><code>lua_dump</code></a> calls the writer, |
|
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|
4645 passing along the buffer to be written (<code>p</code>), |
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4646 its size (<code>sz</code>), |
|
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4647 and the <code>data</code> parameter supplied to <a href="#lua_dump"><code>lua_dump</code></a>. |
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4648 |
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4649 |
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4650 <p> |
|
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4651 The writer returns an error code: |
|
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4652 0 means no errors; |
|
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|
4653 any other value means an error and stops <a href="#lua_dump"><code>lua_dump</code></a> from |
|
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4654 calling the writer again. |
|
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|
4655 |
|
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|
4656 |
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4657 |
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4658 |
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4659 |
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4660 <hr><h3><a name="lua_xmove"><code>lua_xmove</code></a></h3><p> |
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4661 <span class="apii">[-?, +?, –]</span> |
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|
4662 <pre>void lua_xmove (lua_State *from, lua_State *to, int n);</pre> |
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4663 |
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4664 <p> |
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4665 Exchange values between different threads of the same state. |
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4666 |
|
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|
4667 |
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4668 <p> |
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|
4669 This function pops <code>n</code> values from the stack <code>from</code>, |
|
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|
4670 and pushes them onto the stack <code>to</code>. |
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|
4671 |
|
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|
4672 |
|
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|
4673 |
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|
4674 |
|
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|
4675 |
|
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|
4676 <hr><h3><a name="lua_yield"><code>lua_yield</code></a></h3><p> |
|
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|
4677 <span class="apii">[-?, +?, <em>e</em>]</span> |
|
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|
4678 <pre>int lua_yield (lua_State *L, int nresults);</pre> |
|
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|
4679 |
|
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|
4680 <p> |
|
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|
4681 This function is equivalent to <a href="#lua_yieldk"><code>lua_yieldk</code></a>, |
|
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|
4682 but it has no continuation (see <a href="#4.7">§4.7</a>). |
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|
4683 Therefore, when the thread resumes, |
|
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|
4684 it continues the function that called |
|
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|
4685 the function calling <code>lua_yield</code>. |
|
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|
4686 |
|
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|
4687 |
|
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|
4688 |
|
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|
4689 |
|
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|
4690 |
|
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|
4691 <hr><h3><a name="lua_yieldk"><code>lua_yieldk</code></a></h3><p> |
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|
4692 <span class="apii">[-?, +?, <em>e</em>]</span> |
|
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|
4693 <pre>int lua_yieldk (lua_State *L, |
|
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4694 int nresults, |
|
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4695 lua_KContext ctx, |
|
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|
4696 lua_KFunction k);</pre> |
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4697 |
|
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4698 <p> |
|
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4699 Yields a coroutine (thread). |
|
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|
4700 |
|
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|
4701 |
|
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|
4702 <p> |
|
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|
4703 When a C function calls <a href="#lua_yieldk"><code>lua_yieldk</code></a>, |
|
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4704 the running coroutine suspends its execution, |
|
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4705 and the call to <a href="#lua_resume"><code>lua_resume</code></a> that started this coroutine returns. |
|
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|
4706 The parameter <code>nresults</code> is the number of values from the stack |
|
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|
4707 that will be passed as results to <a href="#lua_resume"><code>lua_resume</code></a>. |
|
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|
4708 |
|
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|
4709 |
|
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|
4710 <p> |
|
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|
4711 When the coroutine is resumed again, |
|
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|
4712 Lua calls the given continuation function <code>k</code> to continue |
|
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|
4713 the execution of the C function that yielded (see <a href="#4.7">§4.7</a>). |
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|
4714 This continuation function receives the same stack |
|
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|
4715 from the previous function, |
|
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|
4716 with the <code>n</code> results removed and |
|
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|
4717 replaced by the arguments passed to <a href="#lua_resume"><code>lua_resume</code></a>. |
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|
4718 Moreover, |
|
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|
4719 the continuation function receives the value <code>ctx</code> |
|
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|
4720 that was passed to <a href="#lua_yieldk"><code>lua_yieldk</code></a>. |
|
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4721 |
|
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4722 |
|
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|
4723 <p> |
|
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|
4724 Usually, this function does not return; |
|
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|
4725 when the coroutine eventually resumes, |
|
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|
4726 it continues executing the continuation function. |
|
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|
4727 However, there is one special case, |
|
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|
4728 which is when this function is called |
|
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|
4729 from inside a line hook (see <a href="#4.9">§4.9</a>). |
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4730 In that case, <code>lua_yieldk</code> should be called with no continuation |
|
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|
4731 (probably in the form of <a href="#lua_yield"><code>lua_yield</code></a>), |
|
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|
4732 and the hook should return immediately after the call. |
|
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|
4733 Lua will yield and, |
|
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|
4734 when the coroutine resumes again, |
|
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|
4735 it will continue the normal execution |
|
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|
4736 of the (Lua) function that triggered the hook. |
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|
4737 |
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|
4738 |
|
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|
4739 <p> |
|
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|
4740 This function can raise an error if it is called from a thread |
|
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|
4741 with a pending C call with no continuation function, |
|
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|
4742 or it is called from a thread that is not running inside a resume |
|
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4743 (e.g., the main thread). |
|
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4744 |
|
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|
4745 |
|
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|
4746 |
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|
4747 |
|
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|
4748 |
|
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|
4749 |
|
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|
4750 |
|
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|
4751 <h2>4.9 – <a name="4.9">The Debug Interface</a></h2> |
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4752 |
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|
4753 <p> |
|
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|
4754 Lua has no built-in debugging facilities. |
|
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|
4755 Instead, it offers a special interface |
|
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|
4756 by means of functions and <em>hooks</em>. |
|
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|
4757 This interface allows the construction of different |
|
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|
4758 kinds of debuggers, profilers, and other tools |
|
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|
4759 that need "inside information" from the interpreter. |
|
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|
4760 |
|
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|
4761 |
|
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|
4762 |
|
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|
4763 <hr><h3><a name="lua_Debug"><code>lua_Debug</code></a></h3> |
|
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|
4764 <pre>typedef struct lua_Debug { |
|
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|
4765 int event; |
|
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|
4766 const char *name; /* (n) */ |
|
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|
4767 const char *namewhat; /* (n) */ |
|
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|
4768 const char *what; /* (S) */ |
|
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|
4769 const char *source; /* (S) */ |
|
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|
4770 int currentline; /* (l) */ |
|
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|
4771 int linedefined; /* (S) */ |
|
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|
4772 int lastlinedefined; /* (S) */ |
|
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|
4773 unsigned char nups; /* (u) number of upvalues */ |
|
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|
4774 unsigned char nparams; /* (u) number of parameters */ |
|
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|
4775 char isvararg; /* (u) */ |
|
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|
4776 char istailcall; /* (t) */ |
|
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|
4777 char short_src[LUA_IDSIZE]; /* (S) */ |
|
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|
4778 /* private part */ |
|
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|
4779 <em>other fields</em> |
|
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|
4780 } lua_Debug;</pre> |
|
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|
4781 |
|
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|
4782 <p> |
|
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|
4783 A structure used to carry different pieces of |
|
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|
4784 information about a function or an activation record. |
|
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|
4785 <a href="#lua_getstack"><code>lua_getstack</code></a> fills only the private part |
|
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|
4786 of this structure, for later use. |
|
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|
4787 To fill the other fields of <a href="#lua_Debug"><code>lua_Debug</code></a> with useful information, |
|
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|
4788 call <a href="#lua_getinfo"><code>lua_getinfo</code></a>. |
|
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|
4789 |
|
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|
4790 |
|
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|
4791 <p> |
|
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|
4792 The fields of <a href="#lua_Debug"><code>lua_Debug</code></a> have the following meaning: |
|
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|
4793 |
|
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diff
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|
4794 <ul> |
|
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|
4795 |
|
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|
4796 <li><b><code>source</code>: </b> |
|
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|
4797 the name of the chunk that created the function. |
|
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|
4798 If <code>source</code> starts with a '<code>@</code>', |
|
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|
4799 it means that the function was defined in a file where |
|
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|
4800 the file name follows the '<code>@</code>'. |
|
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|
4801 If <code>source</code> starts with a '<code>=</code>', |
|
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|
4802 the remainder of its contents describe the source in a user-dependent manner. |
|
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|
4803 Otherwise, |
|
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|
4804 the function was defined in a string where |
|
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|
4805 <code>source</code> is that string. |
|
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|
4806 </li> |
|
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|
4807 |
|
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|
4808 <li><b><code>short_src</code>: </b> |
|
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|
4809 a "printable" version of <code>source</code>, to be used in error messages. |
|
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|
4810 </li> |
|
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|
4811 |
|
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|
4812 <li><b><code>linedefined</code>: </b> |
|
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|
4813 the line number where the definition of the function starts. |
|
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|
4814 </li> |
|
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|
4815 |
|
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|
4816 <li><b><code>lastlinedefined</code>: </b> |
|
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4817 the line number where the definition of the function ends. |
|
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|
4818 </li> |
|
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|
4819 |
|
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|
4820 <li><b><code>what</code>: </b> |
|
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|
4821 the string <code>"Lua"</code> if the function is a Lua function, |
|
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|
4822 <code>"C"</code> if it is a C function, |
|
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|
4823 <code>"main"</code> if it is the main part of a chunk. |
|
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|
4824 </li> |
|
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|
4825 |
|
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|
4826 <li><b><code>currentline</code>: </b> |
|
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4827 the current line where the given function is executing. |
|
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|
4828 When no line information is available, |
|
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|
4829 <code>currentline</code> is set to -1. |
|
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|
4830 </li> |
|
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|
4831 |
|
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|
4832 <li><b><code>name</code>: </b> |
|
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|
4833 a reasonable name for the given function. |
|
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|
4834 Because functions in Lua are first-class values, |
|
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|
4835 they do not have a fixed name: |
|
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|
4836 some functions can be the value of multiple global variables, |
|
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4837 while others can be stored only in a table field. |
|
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|
4838 The <code>lua_getinfo</code> function checks how the function was |
|
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|
4839 called to find a suitable name. |
|
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diff
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|
4840 If it cannot find a name, |
|
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|
4841 then <code>name</code> is set to <code>NULL</code>. |
|
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|
4842 </li> |
|
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diff
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|
4843 |
|
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|
4844 <li><b><code>namewhat</code>: </b> |
|
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|
4845 explains the <code>name</code> field. |
|
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|
4846 The value of <code>namewhat</code> can be |
|
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|
4847 <code>"global"</code>, <code>"local"</code>, <code>"method"</code>, |
|
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|
4848 <code>"field"</code>, <code>"upvalue"</code>, or <code>""</code> (the empty string), |
|
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|
4849 according to how the function was called. |
|
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|
4850 (Lua uses the empty string when no other option seems to apply.) |
|
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|
4851 </li> |
|
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|
4852 |
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4853 <li><b><code>istailcall</code>: </b> |
|
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|
4854 true if this function invocation was called by a tail call. |
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|
4855 In this case, the caller of this level is not in the stack. |
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|
4856 </li> |
|
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|
4857 |
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|
4858 <li><b><code>nups</code>: </b> |
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|
4859 the number of upvalues of the function. |
|
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|
4860 </li> |
|
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|
4861 |
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|
4862 <li><b><code>nparams</code>: </b> |
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|
4863 the number of fixed parameters of the function |
|
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|
4864 (always 0 for C functions). |
|
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|
4865 </li> |
|
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|
4866 |
|
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|
4867 <li><b><code>isvararg</code>: </b> |
|
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|
4868 true if the function is a vararg function |
|
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|
4869 (always true for C functions). |
|
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|
4870 </li> |
|
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|
4871 |
|
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|
4872 </ul> |
|
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|
4873 |
|
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diff
changeset
|
4874 |
|
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diff
changeset
|
4875 |
|
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diff
changeset
|
4876 |
|
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|
4877 <hr><h3><a name="lua_gethook"><code>lua_gethook</code></a></h3><p> |
|
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|
4878 <span class="apii">[-0, +0, –]</span> |
|
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|
4879 <pre>lua_Hook lua_gethook (lua_State *L);</pre> |
|
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|
4880 |
|
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|
4881 <p> |
|
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|
4882 Returns the current hook function. |
|
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|
4883 |
|
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|
4884 |
|
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diff
changeset
|
4885 |
|
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changeset
|
4886 |
|
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|
4887 |
|
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|
4888 <hr><h3><a name="lua_gethookcount"><code>lua_gethookcount</code></a></h3><p> |
|
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|
4889 <span class="apii">[-0, +0, –]</span> |
|
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diff
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|
4890 <pre>int lua_gethookcount (lua_State *L);</pre> |
|
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|
4891 |
|
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|
4892 <p> |
|
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|
4893 Returns the current hook count. |
|
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|
4894 |
|
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diff
changeset
|
4895 |
|
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diff
changeset
|
4896 |
|
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diff
changeset
|
4897 |
|
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diff
changeset
|
4898 |
|
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|
4899 <hr><h3><a name="lua_gethookmask"><code>lua_gethookmask</code></a></h3><p> |
|
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|
4900 <span class="apii">[-0, +0, –]</span> |
|
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|
4901 <pre>int lua_gethookmask (lua_State *L);</pre> |
|
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|
4902 |
|
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|
4903 <p> |
|
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|
4904 Returns the current hook mask. |
|
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|
4905 |
|
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diff
changeset
|
4906 |
|
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diff
changeset
|
4907 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
4908 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
4909 |
|
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|
4910 <hr><h3><a name="lua_getinfo"><code>lua_getinfo</code></a></h3><p> |
|
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|
4911 <span class="apii">[-(0|1), +(0|1|2), <em>e</em>]</span> |
|
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|
4912 <pre>int lua_getinfo (lua_State *L, const char *what, lua_Debug *ar);</pre> |
|
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|
4913 |
|
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|
4914 <p> |
|
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|
4915 Gets information about a specific function or function invocation. |
|
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|
4916 |
|
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|
4917 |
|
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|
4918 <p> |
|
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|
4919 To get information about a function invocation, |
|
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|
4920 the parameter <code>ar</code> must be a valid activation record that was |
|
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|
4921 filled by a previous call to <a href="#lua_getstack"><code>lua_getstack</code></a> or |
|
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|
4922 given as argument to a hook (see <a href="#lua_Hook"><code>lua_Hook</code></a>). |
|
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|
4923 |
|
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|
4924 |
|
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|
4925 <p> |
|
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|
4926 To get information about a function you push it onto the stack |
|
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|
4927 and start the <code>what</code> string with the character '<code>></code>'. |
|
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|
4928 (In that case, |
|
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|
4929 <code>lua_getinfo</code> pops the function from the top of the stack.) |
|
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|
4930 For instance, to know in which line a function <code>f</code> was defined, |
|
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|
4931 you can write the following code: |
|
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|
4932 |
|
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|
4933 <pre> |
|
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|
4934 lua_Debug ar; |
|
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|
4935 lua_getglobal(L, "f"); /* get global 'f' */ |
|
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|
4936 lua_getinfo(L, ">S", &ar); |
|
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|
4937 printf("%d\n", ar.linedefined); |
|
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|
4938 </pre> |
|
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|
4939 |
|
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|
4940 <p> |
|
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|
4941 Each character in the string <code>what</code> |
|
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|
4942 selects some fields of the structure <code>ar</code> to be filled or |
|
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4943 a value to be pushed on the stack: |
|
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|
4944 |
|
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|
4945 <ul> |
|
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|
4946 |
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|
4947 <li><b>'<code>n</code>': </b> fills in the field <code>name</code> and <code>namewhat</code>; |
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|
4948 </li> |
|
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|
4949 |
|
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|
4950 <li><b>'<code>S</code>': </b> |
|
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|
4951 fills in the fields <code>source</code>, <code>short_src</code>, |
|
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|
4952 <code>linedefined</code>, <code>lastlinedefined</code>, and <code>what</code>; |
|
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|
4953 </li> |
|
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|
4954 |
|
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|
4955 <li><b>'<code>l</code>': </b> fills in the field <code>currentline</code>; |
|
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4956 </li> |
|
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4957 |
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4958 <li><b>'<code>t</code>': </b> fills in the field <code>istailcall</code>; |
|
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4959 </li> |
|
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4960 |
|
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4961 <li><b>'<code>u</code>': </b> fills in the fields |
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4962 <code>nups</code>, <code>nparams</code>, and <code>isvararg</code>; |
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4963 </li> |
|
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4964 |
|
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4965 <li><b>'<code>f</code>': </b> |
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4966 pushes onto the stack the function that is |
|
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4967 running at the given level; |
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4968 </li> |
|
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4969 |
|
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4970 <li><b>'<code>L</code>': </b> |
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4971 pushes onto the stack a table whose indices are the |
|
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|
4972 numbers of the lines that are valid on the function. |
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|
4973 (A <em>valid line</em> is a line with some associated code, |
|
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4974 that is, a line where you can put a break point. |
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|
4975 Non-valid lines include empty lines and comments.) |
|
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4976 |
|
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|
4977 |
|
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|
4978 <p> |
|
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|
4979 If this option is given together with option '<code>f</code>', |
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4980 its table is pushed after the function. |
|
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|
4981 </li> |
|
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|
4982 |
|
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|
4983 </ul> |
|
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4984 |
|
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|
4985 <p> |
|
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|
4986 This function returns 0 on error |
|
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|
4987 (for instance, an invalid option in <code>what</code>). |
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4988 |
|
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|
4989 |
|
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|
4990 |
|
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|
4991 |
|
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|
4992 |
|
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|
4993 <hr><h3><a name="lua_getlocal"><code>lua_getlocal</code></a></h3><p> |
|
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|
4994 <span class="apii">[-0, +(0|1), –]</span> |
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|
4995 <pre>const char *lua_getlocal (lua_State *L, const lua_Debug *ar, int n);</pre> |
|
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4996 |
|
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|
4997 <p> |
|
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|
4998 Gets information about a local variable of |
|
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|
4999 a given activation record or a given function. |
|
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|
5000 |
|
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|
5001 |
|
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|
5002 <p> |
|
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|
5003 In the first case, |
|
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|
5004 the parameter <code>ar</code> must be a valid activation record that was |
|
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|
5005 filled by a previous call to <a href="#lua_getstack"><code>lua_getstack</code></a> or |
|
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|
5006 given as argument to a hook (see <a href="#lua_Hook"><code>lua_Hook</code></a>). |
|
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|
5007 The index <code>n</code> selects which local variable to inspect; |
|
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|
5008 see <a href="#pdf-debug.getlocal"><code>debug.getlocal</code></a> for details about variable indices |
|
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|
5009 and names. |
|
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|
5010 |
|
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|
5011 |
|
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|
5012 <p> |
|
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|
5013 <a href="#lua_getlocal"><code>lua_getlocal</code></a> pushes the variable's value onto the stack |
|
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|
5014 and returns its name. |
|
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|
5015 |
|
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|
5016 |
|
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|
5017 <p> |
|
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|
5018 In the second case, <code>ar</code> must be <code>NULL</code> and the function |
|
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|
5019 to be inspected must be at the top of the stack. |
|
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|
5020 In this case, only parameters of Lua functions are visible |
|
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|
5021 (as there is no information about what variables are active) |
|
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|
5022 and no values are pushed onto the stack. |
|
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|
5023 |
|
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|
5024 |
|
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|
5025 <p> |
|
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|
5026 Returns <code>NULL</code> (and pushes nothing) |
|
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|
5027 when the index is greater than |
|
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|
5028 the number of active local variables. |
|
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|
5029 |
|
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diff
changeset
|
5030 |
|
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changeset
|
5031 |
|
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changeset
|
5032 |
|
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changeset
|
5033 |
|
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|
5034 <hr><h3><a name="lua_getstack"><code>lua_getstack</code></a></h3><p> |
|
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|
5035 <span class="apii">[-0, +0, –]</span> |
|
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|
5036 <pre>int lua_getstack (lua_State *L, int level, lua_Debug *ar);</pre> |
|
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|
5037 |
|
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|
5038 <p> |
|
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|
5039 Gets information about the interpreter runtime stack. |
|
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|
5040 |
|
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changeset
|
5041 |
|
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|
5042 <p> |
|
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|
5043 This function fills parts of a <a href="#lua_Debug"><code>lua_Debug</code></a> structure with |
|
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|
5044 an identification of the <em>activation record</em> |
|
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|
5045 of the function executing at a given level. |
|
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|
5046 Level 0 is the current running function, |
|
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|
5047 whereas level <em>n+1</em> is the function that has called level <em>n</em> |
|
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|
5048 (except for tail calls, which do not count on the stack). |
|
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|
5049 When there are no errors, <a href="#lua_getstack"><code>lua_getstack</code></a> returns 1; |
|
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|
5050 when called with a level greater than the stack depth, |
|
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|
5051 it returns 0. |
|
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changeset
|
5052 |
|
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changeset
|
5053 |
|
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changeset
|
5054 |
|
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changeset
|
5055 |
|
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changeset
|
5056 |
|
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|
5057 <hr><h3><a name="lua_getupvalue"><code>lua_getupvalue</code></a></h3><p> |
|
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|
5058 <span class="apii">[-0, +(0|1), –]</span> |
|
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|
5059 <pre>const char *lua_getupvalue (lua_State *L, int funcindex, int n);</pre> |
|
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|
5060 |
|
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|
5061 <p> |
|
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changeset
|
5062 Gets information about a closure's upvalue. |
|
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|
5063 (For Lua functions, |
|
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|
5064 upvalues are the external local variables that the function uses, |
|
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|
5065 and that are consequently included in its closure.) |
|
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|
5066 <a href="#lua_getupvalue"><code>lua_getupvalue</code></a> gets the index <code>n</code> of an upvalue, |
|
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|
5067 pushes the upvalue's value onto the stack, |
|
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|
5068 and returns its name. |
|
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|
5069 <code>funcindex</code> points to the closure in the stack. |
|
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|
5070 (Upvalues have no particular order, |
|
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|
5071 as they are active through the whole function. |
|
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|
5072 So, they are numbered in an arbitrary order.) |
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5073 |
|
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5074 |
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5075 <p> |
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5076 Returns <code>NULL</code> (and pushes nothing) |
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5077 when the index is greater than the number of upvalues. |
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5078 For C functions, this function uses the empty string <code>""</code> |
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5079 as a name for all upvalues. |
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5080 |
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5081 |
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5082 |
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|
5083 |
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5084 |
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5085 <hr><h3><a name="lua_Hook"><code>lua_Hook</code></a></h3> |
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5086 <pre>typedef void (*lua_Hook) (lua_State *L, lua_Debug *ar);</pre> |
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5087 |
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5088 <p> |
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5089 Type for debugging hook functions. |
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5090 |
|
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5091 |
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5092 <p> |
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5093 Whenever a hook is called, its <code>ar</code> argument has its field |
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5094 <code>event</code> set to the specific event that triggered the hook. |
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5095 Lua identifies these events with the following constants: |
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5096 <a name="pdf-LUA_HOOKCALL"><code>LUA_HOOKCALL</code></a>, <a name="pdf-LUA_HOOKRET"><code>LUA_HOOKRET</code></a>, |
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5097 <a name="pdf-LUA_HOOKTAILCALL"><code>LUA_HOOKTAILCALL</code></a>, <a name="pdf-LUA_HOOKLINE"><code>LUA_HOOKLINE</code></a>, |
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5098 and <a name="pdf-LUA_HOOKCOUNT"><code>LUA_HOOKCOUNT</code></a>. |
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5099 Moreover, for line events, the field <code>currentline</code> is also set. |
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5100 To get the value of any other field in <code>ar</code>, |
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5101 the hook must call <a href="#lua_getinfo"><code>lua_getinfo</code></a>. |
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5102 |
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5103 |
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5104 <p> |
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5105 For call events, <code>event</code> can be <code>LUA_HOOKCALL</code>, |
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5106 the normal value, or <code>LUA_HOOKTAILCALL</code>, for a tail call; |
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5107 in this case, there will be no corresponding return event. |
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5108 |
|
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5109 |
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5110 <p> |
|
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5111 While Lua is running a hook, it disables other calls to hooks. |
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5112 Therefore, if a hook calls back Lua to execute a function or a chunk, |
|
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5113 this execution occurs without any calls to hooks. |
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5114 |
|
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5115 |
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5116 <p> |
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5117 Hook functions cannot have continuations, |
|
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5118 that is, they cannot call <a href="#lua_yieldk"><code>lua_yieldk</code></a>, |
|
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5119 <a href="#lua_pcallk"><code>lua_pcallk</code></a>, or <a href="#lua_callk"><code>lua_callk</code></a> with a non-null <code>k</code>. |
|
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5120 |
|
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5121 |
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5122 <p> |
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5123 Hook functions can yield under the following conditions: |
|
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5124 Only count and line events can yield |
|
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5125 and they cannot yield any value; |
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5126 to yield a hook function must finish its execution |
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5127 calling <a href="#lua_yield"><code>lua_yield</code></a> with <code>nresults</code> equal to zero. |
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5128 |
|
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5129 |
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|
5130 |
|
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|
5131 |
|
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|
5132 |
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5133 <hr><h3><a name="lua_sethook"><code>lua_sethook</code></a></h3><p> |
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5134 <span class="apii">[-0, +0, –]</span> |
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5135 <pre>void lua_sethook (lua_State *L, lua_Hook f, int mask, int count);</pre> |
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5136 |
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5137 <p> |
|
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|
5138 Sets the debugging hook function. |
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5139 |
|
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5140 |
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5141 <p> |
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|
5142 Argument <code>f</code> is the hook function. |
|
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|
5143 <code>mask</code> specifies on which events the hook will be called: |
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5144 it is formed by a bitwise or of the constants |
|
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|
5145 <a name="pdf-LUA_MASKCALL"><code>LUA_MASKCALL</code></a>, |
|
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5146 <a name="pdf-LUA_MASKRET"><code>LUA_MASKRET</code></a>, |
|
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5147 <a name="pdf-LUA_MASKLINE"><code>LUA_MASKLINE</code></a>, |
|
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5148 and <a name="pdf-LUA_MASKCOUNT"><code>LUA_MASKCOUNT</code></a>. |
|
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5149 The <code>count</code> argument is only meaningful when the mask |
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5150 includes <code>LUA_MASKCOUNT</code>. |
|
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5151 For each event, the hook is called as explained below: |
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|
5152 |
|
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|
5153 <ul> |
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5154 |
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5155 <li><b>The call hook: </b> is called when the interpreter calls a function. |
|
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5156 The hook is called just after Lua enters the new function, |
|
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5157 before the function gets its arguments. |
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5158 </li> |
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5159 |
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5160 <li><b>The return hook: </b> is called when the interpreter returns from a function. |
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5161 The hook is called just before Lua leaves the function. |
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5162 There is no standard way to access the values |
|
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5163 to be returned by the function. |
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5164 </li> |
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5165 |
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5166 <li><b>The line hook: </b> is called when the interpreter is about to |
|
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5167 start the execution of a new line of code, |
|
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5168 or when it jumps back in the code (even to the same line). |
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5169 (This event only happens while Lua is executing a Lua function.) |
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5170 </li> |
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5171 |
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5172 <li><b>The count hook: </b> is called after the interpreter executes every |
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5173 <code>count</code> instructions. |
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5174 (This event only happens while Lua is executing a Lua function.) |
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5175 </li> |
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5176 |
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5177 </ul> |
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5178 |
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5179 <p> |
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5180 A hook is disabled by setting <code>mask</code> to zero. |
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5181 |
|
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5182 |
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5183 |
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5184 |
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5185 |
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5186 <hr><h3><a name="lua_setlocal"><code>lua_setlocal</code></a></h3><p> |
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5187 <span class="apii">[-(0|1), +0, –]</span> |
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5188 <pre>const char *lua_setlocal (lua_State *L, const lua_Debug *ar, int n);</pre> |
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5189 |
|
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5190 <p> |
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5191 Sets the value of a local variable of a given activation record. |
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5192 Parameters <code>ar</code> and <code>n</code> are as in <a href="#lua_getlocal"><code>lua_getlocal</code></a> |
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5193 (see <a href="#lua_getlocal"><code>lua_getlocal</code></a>). |
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5194 <a href="#lua_setlocal"><code>lua_setlocal</code></a> assigns the value at the top of the stack |
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5195 to the variable and returns its name. |
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5196 It also pops the value from the stack. |
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5197 |
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5198 |
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5199 <p> |
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5200 Returns <code>NULL</code> (and pops nothing) |
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5201 when the index is greater than |
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5202 the number of active local variables. |
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5203 |
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5204 |
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5205 |
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5206 |
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5207 |
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5208 <hr><h3><a name="lua_setupvalue"><code>lua_setupvalue</code></a></h3><p> |
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5209 <span class="apii">[-(0|1), +0, –]</span> |
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5210 <pre>const char *lua_setupvalue (lua_State *L, int funcindex, int n);</pre> |
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5211 |
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5212 <p> |
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5213 Sets the value of a closure's upvalue. |
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5214 It assigns the value at the top of the stack |
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5215 to the upvalue and returns its name. |
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5216 It also pops the value from the stack. |
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5217 Parameters <code>funcindex</code> and <code>n</code> are as in the <a href="#lua_getupvalue"><code>lua_getupvalue</code></a> |
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5218 (see <a href="#lua_getupvalue"><code>lua_getupvalue</code></a>). |
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5219 |
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5220 |
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5221 <p> |
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5222 Returns <code>NULL</code> (and pops nothing) |
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5223 when the index is greater than the number of upvalues. |
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5224 |
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5225 |
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5226 |
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5227 |
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5228 |
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5229 <hr><h3><a name="lua_upvalueid"><code>lua_upvalueid</code></a></h3><p> |
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5230 <span class="apii">[-0, +0, –]</span> |
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5231 <pre>void *lua_upvalueid (lua_State *L, int funcindex, int n);</pre> |
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5232 |
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5233 <p> |
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5234 Returns a unique identifier for the upvalue numbered <code>n</code> |
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5235 from the closure at index <code>funcindex</code>. |
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5236 Parameters <code>funcindex</code> and <code>n</code> are as in the <a href="#lua_getupvalue"><code>lua_getupvalue</code></a> |
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5237 (see <a href="#lua_getupvalue"><code>lua_getupvalue</code></a>) |
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5238 (but <code>n</code> cannot be greater than the number of upvalues). |
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5239 |
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5240 |
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5241 <p> |
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5242 These unique identifiers allow a program to check whether different |
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5243 closures share upvalues. |
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5244 Lua closures that share an upvalue |
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5245 (that is, that access a same external local variable) |
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5246 will return identical ids for those upvalue indices. |
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5247 |
|
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|
5248 |
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5249 |
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5250 |
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5251 |
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5252 <hr><h3><a name="lua_upvaluejoin"><code>lua_upvaluejoin</code></a></h3><p> |
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5253 <span class="apii">[-0, +0, –]</span> |
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|
5254 <pre>void lua_upvaluejoin (lua_State *L, int funcindex1, int n1, |
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5255 int funcindex2, int n2);</pre> |
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5256 |
|
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5257 <p> |
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5258 Make the <code>n1</code>-th upvalue of the Lua closure at index <code>funcindex1</code> |
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5259 refer to the <code>n2</code>-th upvalue of the Lua closure at index <code>funcindex2</code>. |
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|
5260 |
|
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|
5261 |
|
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|
5262 |
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5263 |
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|
5264 |
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|
5265 |
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5266 |
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|
5267 <h1>5 – <a name="5">The Auxiliary Library</a></h1> |
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5268 |
|
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5269 <p> |
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|
5270 |
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|
5271 The <em>auxiliary library</em> provides several convenient functions |
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5272 to interface C with Lua. |
|
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5273 While the basic API provides the primitive functions for all |
|
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5274 interactions between C and Lua, |
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5275 the auxiliary library provides higher-level functions for some |
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5276 common tasks. |
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|
5277 |
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5278 |
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5279 <p> |
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5280 All functions and types from the auxiliary library |
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5281 are defined in header file <code>lauxlib.h</code> and |
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5282 have a prefix <code>luaL_</code>. |
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5283 |
|
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5284 |
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5285 <p> |
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5286 All functions in the auxiliary library are built on |
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5287 top of the basic API, |
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5288 and so they provide nothing that cannot be done with that API. |
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5289 Nevertheless, the use of the auxiliary library ensures |
|
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5290 more consistency to your code. |
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5291 |
|
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5292 |
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5293 <p> |
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5294 Several functions in the auxiliary library use internally some |
|
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5295 extra stack slots. |
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5296 When a function in the auxiliary library uses less than five slots, |
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5297 it does not check the stack size; |
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5298 it simply assumes that there are enough slots. |
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5299 |
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5300 |
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5301 <p> |
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5302 Several functions in the auxiliary library are used to |
|
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5303 check C function arguments. |
|
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5304 Because the error message is formatted for arguments |
|
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5305 (e.g., "<code>bad argument #1</code>"), |
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5306 you should not use these functions for other stack values. |
|
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5307 |
|
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|
5308 |
|
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5309 <p> |
|
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|
5310 Functions called <code>luaL_check*</code> |
|
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5311 always raise an error if the check is not satisfied. |
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5312 |
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5313 |
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5314 |
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5315 <h2>5.1 – <a name="5.1">Functions and Types</a></h2> |
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5316 |
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5317 <p> |
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5318 Here we list all functions and types from the auxiliary library |
|
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5319 in alphabetical order. |
|
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5320 |
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5321 |
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5322 |
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5323 <hr><h3><a name="luaL_addchar"><code>luaL_addchar</code></a></h3><p> |
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5324 <span class="apii">[-?, +?, <em>e</em>]</span> |
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5325 <pre>void luaL_addchar (luaL_Buffer *B, char c);</pre> |
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5326 |
|
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5327 <p> |
|
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5328 Adds the byte <code>c</code> to the buffer <code>B</code> |
|
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5329 (see <a href="#luaL_Buffer"><code>luaL_Buffer</code></a>). |
|
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|
5330 |
|
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|
5331 |
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5332 |
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|
5333 |
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|
5334 |
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5335 <hr><h3><a name="luaL_addlstring"><code>luaL_addlstring</code></a></h3><p> |
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5336 <span class="apii">[-?, +?, <em>e</em>]</span> |
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|
5337 <pre>void luaL_addlstring (luaL_Buffer *B, const char *s, size_t l);</pre> |
|
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5338 |
|
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5339 <p> |
|
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5340 Adds the string pointed to by <code>s</code> with length <code>l</code> to |
|
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|
5341 the buffer <code>B</code> |
|
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|
5342 (see <a href="#luaL_Buffer"><code>luaL_Buffer</code></a>). |
|
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|
5343 The string can contain embedded zeros. |
|
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|
5344 |
|
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|
5345 |
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|
5346 |
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|
5347 |
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|
5348 |
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|
5349 <hr><h3><a name="luaL_addsize"><code>luaL_addsize</code></a></h3><p> |
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|
5350 <span class="apii">[-?, +?, <em>e</em>]</span> |
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|
5351 <pre>void luaL_addsize (luaL_Buffer *B, size_t n);</pre> |
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5352 |
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5353 <p> |
|
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|
5354 Adds to the buffer <code>B</code> (see <a href="#luaL_Buffer"><code>luaL_Buffer</code></a>) |
|
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|
5355 a string of length <code>n</code> previously copied to the |
|
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|
5356 buffer area (see <a href="#luaL_prepbuffer"><code>luaL_prepbuffer</code></a>). |
|
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|
5357 |
|
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|
5358 |
|
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|
5359 |
|
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|
5360 |
|
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|
5361 |
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|
5362 <hr><h3><a name="luaL_addstring"><code>luaL_addstring</code></a></h3><p> |
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|
5363 <span class="apii">[-?, +?, <em>e</em>]</span> |
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|
5364 <pre>void luaL_addstring (luaL_Buffer *B, const char *s);</pre> |
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|
5365 |
|
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|
5366 <p> |
|
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|
5367 Adds the zero-terminated string pointed to by <code>s</code> |
|
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|
5368 to the buffer <code>B</code> |
|
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|
5369 (see <a href="#luaL_Buffer"><code>luaL_Buffer</code></a>). |
|
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|
5370 |
|
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|
5371 |
|
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|
5372 |
|
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|
5373 |
|
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|
5374 |
|
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|
5375 <hr><h3><a name="luaL_addvalue"><code>luaL_addvalue</code></a></h3><p> |
|
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|
5376 <span class="apii">[-1, +?, <em>e</em>]</span> |
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|
5377 <pre>void luaL_addvalue (luaL_Buffer *B);</pre> |
|
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|
5378 |
|
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|
5379 <p> |
|
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|
5380 Adds the value at the top of the stack |
|
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|
5381 to the buffer <code>B</code> |
|
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|
5382 (see <a href="#luaL_Buffer"><code>luaL_Buffer</code></a>). |
|
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|
5383 Pops the value. |
|
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|
5384 |
|
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|
5385 |
|
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|
5386 <p> |
|
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|
5387 This is the only function on string buffers that can (and must) |
|
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5388 be called with an extra element on the stack, |
|
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|
5389 which is the value to be added to the buffer. |
|
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|
5390 |
|
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|
5391 |
|
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|
5392 |
|
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|
5393 |
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|
5394 |
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|
5395 <hr><h3><a name="luaL_argcheck"><code>luaL_argcheck</code></a></h3><p> |
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5396 <span class="apii">[-0, +0, <em>v</em>]</span> |
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|
5397 <pre>void luaL_argcheck (lua_State *L, |
|
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5398 int cond, |
|
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5399 int arg, |
|
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|
5400 const char *extramsg);</pre> |
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5401 |
|
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|
5402 <p> |
|
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5403 Checks whether <code>cond</code> is true. |
|
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5404 If it is not, raises an error with a standard message (see <a href="#luaL_argerror"><code>luaL_argerror</code></a>). |
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5405 |
|
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|
5406 |
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|
5407 |
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|
5408 |
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|
5409 |
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5410 <hr><h3><a name="luaL_argerror"><code>luaL_argerror</code></a></h3><p> |
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5411 <span class="apii">[-0, +0, <em>v</em>]</span> |
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5412 <pre>int luaL_argerror (lua_State *L, int arg, const char *extramsg);</pre> |
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5413 |
|
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|
5414 <p> |
|
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5415 Raises an error reporting a problem with argument <code>arg</code> |
|
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5416 of the C function that called it, |
|
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5417 using a standard message |
|
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5418 that includes <code>extramsg</code> as a comment: |
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5419 |
|
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|
5420 <pre> |
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5421 bad argument #<em>arg</em> to '<em>funcname</em>' (<em>extramsg</em>) |
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|
5422 </pre><p> |
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|
5423 This function never returns. |
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|
5424 |
|
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|
5425 |
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|
5426 |
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|
5427 |
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|
5428 |
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|
5429 <hr><h3><a name="luaL_Buffer"><code>luaL_Buffer</code></a></h3> |
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|
5430 <pre>typedef struct luaL_Buffer luaL_Buffer;</pre> |
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5431 |
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|
5432 <p> |
|
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|
5433 Type for a <em>string buffer</em>. |
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5434 |
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5435 |
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5436 <p> |
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|
5437 A string buffer allows C code to build Lua strings piecemeal. |
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|
5438 Its pattern of use is as follows: |
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5439 |
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|
5440 <ul> |
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5441 |
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|
5442 <li>First declare a variable <code>b</code> of type <a href="#luaL_Buffer"><code>luaL_Buffer</code></a>.</li> |
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5443 |
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|
5444 <li>Then initialize it with a call <code>luaL_buffinit(L, &b)</code>.</li> |
|
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|
5445 |
|
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|
5446 <li> |
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5447 Then add string pieces to the buffer calling any of |
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5448 the <code>luaL_add*</code> functions. |
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|
5449 </li> |
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5450 |
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5451 <li> |
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5452 Finish by calling <code>luaL_pushresult(&b)</code>. |
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5453 This call leaves the final string on the top of the stack. |
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|
5454 </li> |
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|
5455 |
|
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|
5456 </ul> |
|
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|
5457 |
|
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|
5458 <p> |
|
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|
5459 If you know beforehand the total size of the resulting string, |
|
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|
5460 you can use the buffer like this: |
|
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|
5461 |
|
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|
5462 <ul> |
|
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|
5463 |
|
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|
5464 <li>First declare a variable <code>b</code> of type <a href="#luaL_Buffer"><code>luaL_Buffer</code></a>.</li> |
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|
5465 |
|
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|
5466 <li>Then initialize it and preallocate a space of |
|
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|
5467 size <code>sz</code> with a call <code>luaL_buffinitsize(L, &b, sz)</code>.</li> |
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|
5468 |
|
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|
5469 <li>Then copy the string into that space.</li> |
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|
5470 |
|
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|
5471 <li> |
|
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5472 Finish by calling <code>luaL_pushresultsize(&b, sz)</code>, |
|
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|
5473 where <code>sz</code> is the total size of the resulting string |
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|
5474 copied into that space. |
|
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|
5475 </li> |
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|
5476 |
|
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|
5477 </ul> |
|
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|
5478 |
|
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|
5479 <p> |
|
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|
5480 During its normal operation, |
|
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|
5481 a string buffer uses a variable number of stack slots. |
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|
5482 So, while using a buffer, you cannot assume that you know where |
|
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|
5483 the top of the stack is. |
|
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|
5484 You can use the stack between successive calls to buffer operations |
|
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|
5485 as long as that use is balanced; |
|
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|
5486 that is, |
|
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|
5487 when you call a buffer operation, |
|
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|
5488 the stack is at the same level |
|
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|
5489 it was immediately after the previous buffer operation. |
|
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|
5490 (The only exception to this rule is <a href="#luaL_addvalue"><code>luaL_addvalue</code></a>.) |
|
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|
5491 After calling <a href="#luaL_pushresult"><code>luaL_pushresult</code></a> the stack is back to its |
|
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|
5492 level when the buffer was initialized, |
|
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|
5493 plus the final string on its top. |
|
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|
5494 |
|
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|
5495 |
|
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|
5496 |
|
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|
5497 |
|
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|
5498 |
|
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|
5499 <hr><h3><a name="luaL_buffinit"><code>luaL_buffinit</code></a></h3><p> |
|
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|
5500 <span class="apii">[-0, +0, –]</span> |
|
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|
5501 <pre>void luaL_buffinit (lua_State *L, luaL_Buffer *B);</pre> |
|
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|
5502 |
|
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|
5503 <p> |
|
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|
5504 Initializes a buffer <code>B</code>. |
|
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|
5505 This function does not allocate any space; |
|
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|
5506 the buffer must be declared as a variable |
|
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|
5507 (see <a href="#luaL_Buffer"><code>luaL_Buffer</code></a>). |
|
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|
5508 |
|
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|
5509 |
|
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|
5510 |
|
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|
5511 |
|
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|
5512 |
|
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|
5513 <hr><h3><a name="luaL_buffinitsize"><code>luaL_buffinitsize</code></a></h3><p> |
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|
5514 <span class="apii">[-?, +?, <em>e</em>]</span> |
|
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|
5515 <pre>char *luaL_buffinitsize (lua_State *L, luaL_Buffer *B, size_t sz);</pre> |
|
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|
5516 |
|
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|
5517 <p> |
|
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|
5518 Equivalent to the sequence |
|
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|
5519 <a href="#luaL_buffinit"><code>luaL_buffinit</code></a>, <a href="#luaL_prepbuffsize"><code>luaL_prepbuffsize</code></a>. |
|
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|
5520 |
|
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changeset
|
5521 |
|
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|
5522 |
|
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|
5523 |
|
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|
5524 |
|
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|
5525 <hr><h3><a name="luaL_callmeta"><code>luaL_callmeta</code></a></h3><p> |
|
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|
5526 <span class="apii">[-0, +(0|1), <em>e</em>]</span> |
|
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|
5527 <pre>int luaL_callmeta (lua_State *L, int obj, const char *e);</pre> |
|
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|
5528 |
|
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|
5529 <p> |
|
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|
5530 Calls a metamethod. |
|
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|
5531 |
|
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|
5532 |
|
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|
5533 <p> |
|
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|
5534 If the object at index <code>obj</code> has a metatable and this |
|
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|
5535 metatable has a field <code>e</code>, |
|
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|
5536 this function calls this field passing the object as its only argument. |
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|
5537 In this case this function returns true and pushes onto the |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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diff
changeset
|
5538 stack the value returned by the call. |
|
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parents:
diff
changeset
|
5539 If there is no metatable or no metamethod, |
|
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parents:
diff
changeset
|
5540 this function returns false (without pushing any value on the stack). |
|
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diff
changeset
|
5541 |
|
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parents:
diff
changeset
|
5542 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
5543 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
5544 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
5545 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
5546 <hr><h3><a name="luaL_checkany"><code>luaL_checkany</code></a></h3><p> |
|
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|
5547 <span class="apii">[-0, +0, <em>v</em>]</span> |
|
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|
5548 <pre>void luaL_checkany (lua_State *L, int arg);</pre> |
|
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|
5549 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
5550 <p> |
|
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parents:
diff
changeset
|
5551 Checks whether the function has an argument |
|
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diff
changeset
|
5552 of any type (including <b>nil</b>) at position <code>arg</code>. |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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diff
changeset
|
5553 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
5554 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5555 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5556 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5557 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
5558 <hr><h3><a name="luaL_checkinteger"><code>luaL_checkinteger</code></a></h3><p> |
|
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|
5559 <span class="apii">[-0, +0, <em>v</em>]</span> |
|
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parents:
diff
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|
5560 <pre>lua_Integer luaL_checkinteger (lua_State *L, int arg);</pre> |
|
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diff
changeset
|
5561 |
|
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diff
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|
5562 <p> |
|
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diff
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|
5563 Checks whether the function argument <code>arg</code> is an integer |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
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|
5564 (or can be converted to an integer) |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
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|
5565 and returns this integer cast to a <a href="#lua_Integer"><code>lua_Integer</code></a>. |
|
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diff
changeset
|
5566 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5567 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5568 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5569 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
5570 |
|
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diff
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|
5571 <hr><h3><a name="luaL_checklstring"><code>luaL_checklstring</code></a></h3><p> |
|
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|
5572 <span class="apii">[-0, +0, <em>v</em>]</span> |
|
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diff
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|
5573 <pre>const char *luaL_checklstring (lua_State *L, int arg, size_t *l);</pre> |
|
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|
5574 |
|
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diff
changeset
|
5575 <p> |
|
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diff
changeset
|
5576 Checks whether the function argument <code>arg</code> is a string |
|
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parents:
diff
changeset
|
5577 and returns this string; |
|
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parents:
diff
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|
5578 if <code>l</code> is not <code>NULL</code> fills <code>*l</code> |
|
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|
5579 with the string's length. |
|
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diff
changeset
|
5580 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5581 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5582 <p> |
|
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parents:
diff
changeset
|
5583 This function uses <a href="#lua_tolstring"><code>lua_tolstring</code></a> to get its result, |
|
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diff
changeset
|
5584 so all conversions and caveats of that function apply here. |
|
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diff
changeset
|
5585 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5586 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5587 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5588 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5589 |
|
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diff
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|
5590 <hr><h3><a name="luaL_checknumber"><code>luaL_checknumber</code></a></h3><p> |
|
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|
5591 <span class="apii">[-0, +0, <em>v</em>]</span> |
|
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diff
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|
5592 <pre>lua_Number luaL_checknumber (lua_State *L, int arg);</pre> |
|
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changeset
|
5593 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5594 <p> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5595 Checks whether the function argument <code>arg</code> is a number |
|
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diff
changeset
|
5596 and returns this number. |
|
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parents:
diff
changeset
|
5597 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5598 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5599 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5600 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5601 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
5602 <hr><h3><a name="luaL_checkoption"><code>luaL_checkoption</code></a></h3><p> |
|
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|
5603 <span class="apii">[-0, +0, <em>v</em>]</span> |
|
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diff
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|
5604 <pre>int luaL_checkoption (lua_State *L, |
|
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|
5605 int arg, |
|
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diff
changeset
|
5606 const char *def, |
|
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diff
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|
5607 const char *const lst[]);</pre> |
|
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|
5608 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
5609 <p> |
|
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diff
changeset
|
5610 Checks whether the function argument <code>arg</code> is a string and |
|
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parents:
diff
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|
5611 searches for this string in the array <code>lst</code> |
|
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parents:
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|
5612 (which must be NULL-terminated). |
|
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diff
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|
5613 Returns the index in the array where the string was found. |
|
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|
5614 Raises an error if the argument is not a string or |
|
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diff
changeset
|
5615 if the string cannot be found. |
|
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diff
changeset
|
5616 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5617 |
|
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diff
changeset
|
5618 <p> |
|
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changeset
|
5619 If <code>def</code> is not <code>NULL</code>, |
|
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changeset
|
5620 the function uses <code>def</code> as a default value when |
|
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diff
changeset
|
5621 there is no argument <code>arg</code> or when this argument is <b>nil</b>. |
|
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changeset
|
5622 |
|
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diff
changeset
|
5623 |
|
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changeset
|
5624 <p> |
|
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diff
changeset
|
5625 This is a useful function for mapping strings to C enums. |
|
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diff
changeset
|
5626 (The usual convention in Lua libraries is |
|
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diff
changeset
|
5627 to use strings instead of numbers to select options.) |
|
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diff
changeset
|
5628 |
|
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diff
changeset
|
5629 |
|
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diff
changeset
|
5630 |
|
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diff
changeset
|
5631 |
|
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diff
changeset
|
5632 |
|
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|
5633 <hr><h3><a name="luaL_checkstack"><code>luaL_checkstack</code></a></h3><p> |
|
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|
5634 <span class="apii">[-0, +0, <em>v</em>]</span> |
|
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|
5635 <pre>void luaL_checkstack (lua_State *L, int sz, const char *msg);</pre> |
|
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changeset
|
5636 |
|
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changeset
|
5637 <p> |
|
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changeset
|
5638 Grows the stack size to <code>top + sz</code> elements, |
|
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diff
changeset
|
5639 raising an error if the stack cannot grow to that size. |
|
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diff
changeset
|
5640 <code>msg</code> is an additional text to go into the error message |
|
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|
5641 (or <code>NULL</code> for no additional text). |
|
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changeset
|
5642 |
|
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changeset
|
5643 |
|
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changeset
|
5644 |
|
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changeset
|
5645 |
|
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changeset
|
5646 |
|
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changeset
|
5647 <hr><h3><a name="luaL_checkstring"><code>luaL_checkstring</code></a></h3><p> |
|
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|
5648 <span class="apii">[-0, +0, <em>v</em>]</span> |
|
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|
5649 <pre>const char *luaL_checkstring (lua_State *L, int arg);</pre> |
|
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changeset
|
5650 |
|
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changeset
|
5651 <p> |
|
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diff
changeset
|
5652 Checks whether the function argument <code>arg</code> is a string |
|
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diff
changeset
|
5653 and returns this string. |
|
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diff
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|
5654 |
|
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diff
changeset
|
5655 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
5656 <p> |
|
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diff
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|
5657 This function uses <a href="#lua_tolstring"><code>lua_tolstring</code></a> to get its result, |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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|
5658 so all conversions and caveats of that function apply here. |
|
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diff
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|
5659 |
|
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parents:
diff
changeset
|
5660 |
|
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diff
changeset
|
5661 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5662 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5663 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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|
5664 <hr><h3><a name="luaL_checktype"><code>luaL_checktype</code></a></h3><p> |
|
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|
5665 <span class="apii">[-0, +0, <em>v</em>]</span> |
|
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|
5666 <pre>void luaL_checktype (lua_State *L, int arg, int t);</pre> |
|
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|
5667 |
|
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diff
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|
5668 <p> |
|
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diff
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|
5669 Checks whether the function argument <code>arg</code> has type <code>t</code>. |
|
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|
5670 See <a href="#lua_type"><code>lua_type</code></a> for the encoding of types for <code>t</code>. |
|
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|
5671 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
5672 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5673 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5674 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
5675 |
|
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|
5676 <hr><h3><a name="luaL_checkudata"><code>luaL_checkudata</code></a></h3><p> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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|
5677 <span class="apii">[-0, +0, <em>v</em>]</span> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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|
5678 <pre>void *luaL_checkudata (lua_State *L, int arg, const char *tname);</pre> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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|
5679 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
5680 <p> |
|
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diff
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|
5681 Checks whether the function argument <code>arg</code> is a userdata |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
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|
5682 of the type <code>tname</code> (see <a href="#luaL_newmetatable"><code>luaL_newmetatable</code></a>) and |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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diff
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|
5683 returns the userdata address (see <a href="#lua_touserdata"><code>lua_touserdata</code></a>). |
|
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diff
changeset
|
5684 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5685 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5686 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5687 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5688 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
5689 <hr><h3><a name="luaL_checkversion"><code>luaL_checkversion</code></a></h3><p> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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diff
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|
5690 <span class="apii">[-0, +0, –]</span> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
5691 <pre>void luaL_checkversion (lua_State *L);</pre> |
|
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diff
changeset
|
5692 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
5693 <p> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5694 Checks whether the core running the call, |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
5695 the core that created the Lua state, |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
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|
5696 and the code making the call are all using the same version of Lua. |
|
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parents:
diff
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|
5697 Also checks whether the core running the call |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
5698 and the core that created the Lua state |
|
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parents:
diff
changeset
|
5699 are using the same address space. |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
5700 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5701 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5702 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5703 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5704 |
|
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|
5705 <hr><h3><a name="luaL_dofile"><code>luaL_dofile</code></a></h3><p> |
|
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|
5706 <span class="apii">[-0, +?, <em>e</em>]</span> |
|
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parents:
diff
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|
5707 <pre>int luaL_dofile (lua_State *L, const char *filename);</pre> |
|
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|
5708 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
5709 <p> |
|
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diff
changeset
|
5710 Loads and runs the given file. |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5711 It is defined as the following macro: |
|
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diff
changeset
|
5712 |
|
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diff
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|
5713 <pre> |
|
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diff
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|
5714 (luaL_loadfile(L, filename) || lua_pcall(L, 0, LUA_MULTRET, 0)) |
|
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|
5715 </pre><p> |
|
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diff
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|
5716 It returns false if there are no errors |
|
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parents:
diff
changeset
|
5717 or true in case of errors. |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5718 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5719 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5720 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5721 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5722 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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|
5723 <hr><h3><a name="luaL_dostring"><code>luaL_dostring</code></a></h3><p> |
|
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|
5724 <span class="apii">[-0, +?, –]</span> |
|
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parents:
diff
changeset
|
5725 <pre>int luaL_dostring (lua_State *L, const char *str);</pre> |
|
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diff
changeset
|
5726 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5727 <p> |
|
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parents:
diff
changeset
|
5728 Loads and runs the given string. |
|
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parents:
diff
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|
5729 It is defined as the following macro: |
|
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parents:
diff
changeset
|
5730 |
|
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diff
changeset
|
5731 <pre> |
|
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diff
changeset
|
5732 (luaL_loadstring(L, str) || lua_pcall(L, 0, LUA_MULTRET, 0)) |
|
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changeset
|
5733 </pre><p> |
|
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parents:
diff
changeset
|
5734 It returns false if there are no errors |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5735 or true in case of errors. |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5736 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5737 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5738 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5739 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5740 |
|
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diff
changeset
|
5741 <hr><h3><a name="luaL_error"><code>luaL_error</code></a></h3><p> |
|
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|
5742 <span class="apii">[-0, +0, <em>v</em>]</span> |
|
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|
5743 <pre>int luaL_error (lua_State *L, const char *fmt, ...);</pre> |
|
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changeset
|
5744 |
|
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changeset
|
5745 <p> |
|
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changeset
|
5746 Raises an error. |
|
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diff
changeset
|
5747 The error message format is given by <code>fmt</code> |
|
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changeset
|
5748 plus any extra arguments, |
|
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changeset
|
5749 following the same rules of <a href="#lua_pushfstring"><code>lua_pushfstring</code></a>. |
|
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changeset
|
5750 It also adds at the beginning of the message the file name and |
|
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changeset
|
5751 the line number where the error occurred, |
|
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parents:
diff
changeset
|
5752 if this information is available. |
|
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diff
changeset
|
5753 |
|
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parents:
diff
changeset
|
5754 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5755 <p> |
|
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changeset
|
5756 This function never returns, |
|
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parents:
diff
changeset
|
5757 but it is an idiom to use it in C functions |
|
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changeset
|
5758 as <code>return luaL_error(<em>args</em>)</code>. |
|
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diff
changeset
|
5759 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5760 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5761 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5762 |
|
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diff
changeset
|
5763 |
|
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changeset
|
5764 <hr><h3><a name="luaL_execresult"><code>luaL_execresult</code></a></h3><p> |
|
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changeset
|
5765 <span class="apii">[-0, +3, <em>e</em>]</span> |
|
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changeset
|
5766 <pre>int luaL_execresult (lua_State *L, int stat);</pre> |
|
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changeset
|
5767 |
|
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diff
changeset
|
5768 <p> |
|
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diff
changeset
|
5769 This function produces the return values for |
|
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diff
changeset
|
5770 process-related functions in the standard library |
|
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5771 (<a href="#pdf-os.execute"><code>os.execute</code></a> and <a href="#pdf-io.close"><code>io.close</code></a>). |
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5772 |
|
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5773 |
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|
5774 |
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5775 |
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5776 |
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5777 <hr><h3><a name="luaL_fileresult"><code>luaL_fileresult</code></a></h3><p> |
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5778 <span class="apii">[-0, +(1|3), <em>e</em>]</span> |
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5779 <pre>int luaL_fileresult (lua_State *L, int stat, const char *fname);</pre> |
|
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5780 |
|
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5781 <p> |
|
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|
5782 This function produces the return values for |
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|
5783 file-related functions in the standard library |
|
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|
5784 (<a href="#pdf-io.open"><code>io.open</code></a>, <a href="#pdf-os.rename"><code>os.rename</code></a>, <a href="#pdf-file:seek"><code>file:seek</code></a>, etc.). |
|
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|
5785 |
|
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5786 |
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5787 |
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5788 |
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5789 |
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5790 <hr><h3><a name="luaL_getmetafield"><code>luaL_getmetafield</code></a></h3><p> |
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5791 <span class="apii">[-0, +(0|1), <em>e</em>]</span> |
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|
5792 <pre>int luaL_getmetafield (lua_State *L, int obj, const char *e);</pre> |
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5793 |
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5794 <p> |
|
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|
5795 Pushes onto the stack the field <code>e</code> from the metatable |
|
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|
5796 of the object at index <code>obj</code> and returns the type of pushed value. |
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5797 If the object does not have a metatable, |
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5798 or if the metatable does not have this field, |
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5799 pushes nothing and returns <code>LUA_TNIL</code>. |
|
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5800 |
|
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|
5801 |
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|
5802 |
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|
5803 |
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|
5804 |
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|
5805 <hr><h3><a name="luaL_getmetatable"><code>luaL_getmetatable</code></a></h3><p> |
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5806 <span class="apii">[-0, +1, –]</span> |
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|
5807 <pre>int luaL_getmetatable (lua_State *L, const char *tname);</pre> |
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5808 |
|
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|
5809 <p> |
|
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|
5810 Pushes onto the stack the metatable associated with name <code>tname</code> |
|
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|
5811 in the registry (see <a href="#luaL_newmetatable"><code>luaL_newmetatable</code></a>). |
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5812 If there is no metatable associated with <code>tname</code>, |
|
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5813 returns false and pushes <b>nil</b>. |
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5814 |
|
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|
5815 |
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|
5816 |
|
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|
5817 |
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5818 |
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5819 <hr><h3><a name="luaL_getsubtable"><code>luaL_getsubtable</code></a></h3><p> |
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5820 <span class="apii">[-0, +1, <em>e</em>]</span> |
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5821 <pre>int luaL_getsubtable (lua_State *L, int idx, const char *fname);</pre> |
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5822 |
|
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5823 <p> |
|
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|
5824 Ensures that the value <code>t[fname]</code>, |
|
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5825 where <code>t</code> is the value at index <code>idx</code>, |
|
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5826 is a table, |
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|
5827 and pushes that table onto the stack. |
|
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5828 Returns true if it finds a previous table there |
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5829 and false if it creates a new table. |
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|
5830 |
|
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|
5831 |
|
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|
5832 |
|
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|
5833 |
|
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|
5834 |
|
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|
5835 <hr><h3><a name="luaL_gsub"><code>luaL_gsub</code></a></h3><p> |
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5836 <span class="apii">[-0, +1, <em>e</em>]</span> |
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|
5837 <pre>const char *luaL_gsub (lua_State *L, |
|
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|
5838 const char *s, |
|
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|
5839 const char *p, |
|
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|
5840 const char *r);</pre> |
|
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|
5841 |
|
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|
5842 <p> |
|
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|
5843 Creates a copy of string <code>s</code> by replacing |
|
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|
5844 any occurrence of the string <code>p</code> |
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|
5845 with the string <code>r</code>. |
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|
5846 Pushes the resulting string on the stack and returns it. |
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|
5847 |
|
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|
5848 |
|
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|
5849 |
|
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|
5850 |
|
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|
5851 |
|
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|
5852 <hr><h3><a name="luaL_len"><code>luaL_len</code></a></h3><p> |
|
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|
5853 <span class="apii">[-0, +0, <em>e</em>]</span> |
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|
5854 <pre>lua_Integer luaL_len (lua_State *L, int index);</pre> |
|
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|
5855 |
|
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|
5856 <p> |
|
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|
5857 Returns the "length" of the value at the given index |
|
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5858 as a number; |
|
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|
5859 it is equivalent to the '<code>#</code>' operator in Lua (see <a href="#3.4.7">§3.4.7</a>). |
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5860 Raises an error if the result of the operation is not an integer. |
|
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|
5861 (This case only can happen through metamethods.) |
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5862 |
|
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|
5863 |
|
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|
5864 |
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|
5865 |
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|
5866 |
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5867 <hr><h3><a name="luaL_loadbuffer"><code>luaL_loadbuffer</code></a></h3><p> |
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5868 <span class="apii">[-0, +1, –]</span> |
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5869 <pre>int luaL_loadbuffer (lua_State *L, |
|
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|
5870 const char *buff, |
|
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5871 size_t sz, |
|
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|
5872 const char *name);</pre> |
|
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|
5873 |
|
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|
5874 <p> |
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|
5875 Equivalent to <a href="#luaL_loadbufferx"><code>luaL_loadbufferx</code></a> with <code>mode</code> equal to <code>NULL</code>. |
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|
5876 |
|
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|
5877 |
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|
5878 |
|
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|
5879 |
|
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|
5880 |
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|
5881 <hr><h3><a name="luaL_loadbufferx"><code>luaL_loadbufferx</code></a></h3><p> |
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5882 <span class="apii">[-0, +1, –]</span> |
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5883 <pre>int luaL_loadbufferx (lua_State *L, |
|
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5884 const char *buff, |
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changeset
|
5885 size_t sz, |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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|
5886 const char *name, |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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|
5887 const char *mode);</pre> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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diff
changeset
|
5888 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5889 <p> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
5890 Loads a buffer as a Lua chunk. |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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diff
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|
5891 This function uses <a href="#lua_load"><code>lua_load</code></a> to load the chunk in the |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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diff
changeset
|
5892 buffer pointed to by <code>buff</code> with size <code>sz</code>. |
|
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|
5893 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5894 |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5895 <p> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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diff
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|
5896 This function returns the same results as <a href="#lua_load"><code>lua_load</code></a>. |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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|
5897 <code>name</code> is the chunk name, |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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|
5898 used for debug information and error messages. |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
5899 The string <code>mode</code> works as in function <a href="#lua_load"><code>lua_load</code></a>. |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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changeset
|
5900 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
5901 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5902 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5903 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
5904 |
|
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|
5905 <hr><h3><a name="luaL_loadfile"><code>luaL_loadfile</code></a></h3><p> |
|
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|
5906 <span class="apii">[-0, +1, <em>e</em>]</span> |
|
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|
5907 <pre>int luaL_loadfile (lua_State *L, const char *filename);</pre> |
|
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|
5908 |
|
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diff
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|
5909 <p> |
|
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|
5910 Equivalent to <a href="#luaL_loadfilex"><code>luaL_loadfilex</code></a> with <code>mode</code> equal to <code>NULL</code>. |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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changeset
|
5911 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
5912 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
5913 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
5914 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
5915 |
|
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|
5916 <hr><h3><a name="luaL_loadfilex"><code>luaL_loadfilex</code></a></h3><p> |
|
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|
5917 <span class="apii">[-0, +1, <em>e</em>]</span> |
|
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|
5918 <pre>int luaL_loadfilex (lua_State *L, const char *filename, |
|
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|
5919 const char *mode);</pre> |
|
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|
5920 |
|
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|
5921 <p> |
|
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|
5922 Loads a file as a Lua chunk. |
|
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|
5923 This function uses <a href="#lua_load"><code>lua_load</code></a> to load the chunk in the file |
|
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|
5924 named <code>filename</code>. |
|
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diff
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|
5925 If <code>filename</code> is <code>NULL</code>, |
|
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|
5926 then it loads from the standard input. |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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diff
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|
5927 The first line in the file is ignored if it starts with a <code>#</code>. |
|
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|
5928 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
5929 |
|
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diff
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|
5930 <p> |
|
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diff
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|
5931 The string <code>mode</code> works as in function <a href="#lua_load"><code>lua_load</code></a>. |
|
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changeset
|
5932 |
|
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diff
changeset
|
5933 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5934 <p> |
|
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changeset
|
5935 This function returns the same results as <a href="#lua_load"><code>lua_load</code></a>, |
|
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|
5936 but it has an extra error code <a name="pdf-LUA_ERRFILE"><code>LUA_ERRFILE</code></a> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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|
5937 if it cannot open/read the file or the file has a wrong mode. |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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diff
changeset
|
5938 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5939 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
5940 <p> |
|
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parents:
diff
changeset
|
5941 As <a href="#lua_load"><code>lua_load</code></a>, this function only loads the chunk; |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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|
5942 it does not run it. |
|
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diff
changeset
|
5943 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5944 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
5945 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
5946 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
5947 |
|
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|
5948 <hr><h3><a name="luaL_loadstring"><code>luaL_loadstring</code></a></h3><p> |
|
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|
5949 <span class="apii">[-0, +1, –]</span> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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|
5950 <pre>int luaL_loadstring (lua_State *L, const char *s);</pre> |
|
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|
5951 |
|
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diff
changeset
|
5952 <p> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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diff
changeset
|
5953 Loads a string as a Lua chunk. |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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|
5954 This function uses <a href="#lua_load"><code>lua_load</code></a> to load the chunk in |
|
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changeset
|
5955 the zero-terminated string <code>s</code>. |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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diff
changeset
|
5956 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5957 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
5958 <p> |
|
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diff
changeset
|
5959 This function returns the same results as <a href="#lua_load"><code>lua_load</code></a>. |
|
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diff
changeset
|
5960 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5961 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
5962 <p> |
|
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diff
changeset
|
5963 Also as <a href="#lua_load"><code>lua_load</code></a>, this function only loads the chunk; |
|
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changeset
|
5964 it does not run it. |
|
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diff
changeset
|
5965 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5966 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
5967 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
5968 |
|
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diff
changeset
|
5969 |
|
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|
5970 <hr><h3><a name="luaL_newlib"><code>luaL_newlib</code></a></h3><p> |
|
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|
5971 <span class="apii">[-0, +1, <em>e</em>]</span> |
|
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|
5972 <pre>void luaL_newlib (lua_State *L, const luaL_Reg l[]);</pre> |
|
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changeset
|
5973 |
|
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changeset
|
5974 <p> |
|
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changeset
|
5975 Creates a new table and registers there |
|
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|
5976 the functions in list <code>l</code>. |
|
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changeset
|
5977 |
|
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diff
changeset
|
5978 |
|
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|
5979 <p> |
|
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changeset
|
5980 It is implemented as the following macro: |
|
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|
5981 |
|
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changeset
|
5982 <pre> |
|
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changeset
|
5983 (luaL_newlibtable(L,l), luaL_setfuncs(L,l,0)) |
|
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|
5984 </pre><p> |
|
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|
5985 The array <code>l</code> must be the actual array, |
|
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|
5986 not a pointer to it. |
|
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changeset
|
5987 |
|
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changeset
|
5988 |
|
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diff
changeset
|
5989 |
|
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diff
changeset
|
5990 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
5991 |
|
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changeset
|
5992 <hr><h3><a name="luaL_newlibtable"><code>luaL_newlibtable</code></a></h3><p> |
|
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|
5993 <span class="apii">[-0, +1, <em>e</em>]</span> |
|
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|
5994 <pre>void luaL_newlibtable (lua_State *L, const luaL_Reg l[]);</pre> |
|
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changeset
|
5995 |
|
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diff
changeset
|
5996 <p> |
|
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diff
changeset
|
5997 Creates a new table with a size optimized |
|
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diff
changeset
|
5998 to store all entries in the array <code>l</code> |
|
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changeset
|
5999 (but does not actually store them). |
|
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|
6000 It is intended to be used in conjunction with <a href="#luaL_setfuncs"><code>luaL_setfuncs</code></a> |
|
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|
6001 (see <a href="#luaL_newlib"><code>luaL_newlib</code></a>). |
|
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|
6002 |
|
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|
6003 |
|
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|
6004 <p> |
|
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|
6005 It is implemented as a macro. |
|
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|
6006 The array <code>l</code> must be the actual array, |
|
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|
6007 not a pointer to it. |
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|
6008 |
|
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|
6009 |
|
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|
6010 |
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|
6011 |
|
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diff
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|
6012 |
|
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|
6013 <hr><h3><a name="luaL_newmetatable"><code>luaL_newmetatable</code></a></h3><p> |
|
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6014 <span class="apii">[-0, +1, <em>e</em>]</span> |
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|
6015 <pre>int luaL_newmetatable (lua_State *L, const char *tname);</pre> |
|
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|
6016 |
|
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|
6017 <p> |
|
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|
6018 If the registry already has the key <code>tname</code>, |
|
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|
6019 returns 0. |
|
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|
6020 Otherwise, |
|
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|
6021 creates a new table to be used as a metatable for userdata, |
|
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|
6022 adds to this new table the pair <code>__name = tname</code>, |
|
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|
6023 adds to the registry the pair <code>[tname] = new table</code>, |
|
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6024 and returns 1. |
|
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|
6025 (The entry <code>__name</code> is used by some error-reporting functions.) |
|
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|
6026 |
|
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diff
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|
6027 |
|
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|
6028 <p> |
|
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|
6029 In both cases pushes onto the stack the final value associated |
|
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|
6030 with <code>tname</code> in the registry. |
|
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|
6031 |
|
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diff
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|
6032 |
|
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diff
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|
6033 |
|
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diff
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|
6034 |
|
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diff
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|
6035 |
|
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|
6036 <hr><h3><a name="luaL_newstate"><code>luaL_newstate</code></a></h3><p> |
|
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6037 <span class="apii">[-0, +0, –]</span> |
|
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|
6038 <pre>lua_State *luaL_newstate (void);</pre> |
|
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|
6039 |
|
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|
6040 <p> |
|
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|
6041 Creates a new Lua state. |
|
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|
6042 It calls <a href="#lua_newstate"><code>lua_newstate</code></a> with an |
|
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|
6043 allocator based on the standard C <code>realloc</code> function |
|
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|
6044 and then sets a panic function (see <a href="#4.6">§4.6</a>) that prints |
|
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|
6045 an error message to the standard error output in case of fatal |
|
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|
6046 errors. |
|
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|
6047 |
|
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|
6048 |
|
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|
6049 <p> |
|
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|
6050 Returns the new state, |
|
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|
6051 or <code>NULL</code> if there is a memory allocation error. |
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|
6052 |
|
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diff
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|
6053 |
|
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|
6054 |
|
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|
6055 |
|
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|
6056 |
|
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|
6057 <hr><h3><a name="luaL_openlibs"><code>luaL_openlibs</code></a></h3><p> |
|
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|
6058 <span class="apii">[-0, +0, <em>e</em>]</span> |
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|
6059 <pre>void luaL_openlibs (lua_State *L);</pre> |
|
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|
6060 |
|
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|
6061 <p> |
|
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|
6062 Opens all standard Lua libraries into the given state. |
|
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|
6063 |
|
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changeset
|
6064 |
|
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changeset
|
6065 |
|
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changeset
|
6066 |
|
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changeset
|
6067 |
|
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|
6068 <hr><h3><a name="luaL_optinteger"><code>luaL_optinteger</code></a></h3><p> |
|
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|
6069 <span class="apii">[-0, +0, <em>v</em>]</span> |
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|
6070 <pre>lua_Integer luaL_optinteger (lua_State *L, |
|
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|
6071 int arg, |
|
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|
6072 lua_Integer d);</pre> |
|
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|
6073 |
|
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|
6074 <p> |
|
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|
6075 If the function argument <code>arg</code> is an integer |
|
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|
6076 (or convertible to an integer), |
|
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|
6077 returns this integer. |
|
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|
6078 If this argument is absent or is <b>nil</b>, |
|
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|
6079 returns <code>d</code>. |
|
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|
6080 Otherwise, raises an error. |
|
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changeset
|
6081 |
|
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changeset
|
6082 |
|
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parents:
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changeset
|
6083 |
|
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parents:
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changeset
|
6084 |
|
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changeset
|
6085 |
|
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|
6086 <hr><h3><a name="luaL_optlstring"><code>luaL_optlstring</code></a></h3><p> |
|
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|
6087 <span class="apii">[-0, +0, <em>v</em>]</span> |
|
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|
6088 <pre>const char *luaL_optlstring (lua_State *L, |
|
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|
6089 int arg, |
|
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changeset
|
6090 const char *d, |
|
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|
6091 size_t *l);</pre> |
|
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|
6092 |
|
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|
6093 <p> |
|
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changeset
|
6094 If the function argument <code>arg</code> is a string, |
|
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|
6095 returns this string. |
|
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|
6096 If this argument is absent or is <b>nil</b>, |
|
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changeset
|
6097 returns <code>d</code>. |
|
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changeset
|
6098 Otherwise, raises an error. |
|
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changeset
|
6099 |
|
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changeset
|
6100 |
|
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|
6101 <p> |
|
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|
6102 If <code>l</code> is not <code>NULL</code>, |
|
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|
6103 fills the position <code>*l</code> with the result's length. |
|
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changeset
|
6104 |
|
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changeset
|
6105 |
|
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parents:
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changeset
|
6106 |
|
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parents:
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changeset
|
6107 |
|
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changeset
|
6108 |
|
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|
6109 <hr><h3><a name="luaL_optnumber"><code>luaL_optnumber</code></a></h3><p> |
|
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|
6110 <span class="apii">[-0, +0, <em>v</em>]</span> |
|
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|
6111 <pre>lua_Number luaL_optnumber (lua_State *L, int arg, lua_Number d);</pre> |
|
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|
6112 |
|
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changeset
|
6113 <p> |
|
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changeset
|
6114 If the function argument <code>arg</code> is a number, |
|
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changeset
|
6115 returns this number. |
|
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changeset
|
6116 If this argument is absent or is <b>nil</b>, |
|
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|
6117 returns <code>d</code>. |
|
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6118 Otherwise, raises an error. |
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6119 |
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6120 |
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6121 |
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6122 |
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6123 |
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6124 <hr><h3><a name="luaL_optstring"><code>luaL_optstring</code></a></h3><p> |
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6125 <span class="apii">[-0, +0, <em>v</em>]</span> |
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6126 <pre>const char *luaL_optstring (lua_State *L, |
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6127 int arg, |
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6128 const char *d);</pre> |
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6129 |
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6130 <p> |
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6131 If the function argument <code>arg</code> is a string, |
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6132 returns this string. |
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6133 If this argument is absent or is <b>nil</b>, |
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6134 returns <code>d</code>. |
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6135 Otherwise, raises an error. |
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6136 |
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6137 |
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6138 |
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6139 |
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6140 |
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6141 <hr><h3><a name="luaL_prepbuffer"><code>luaL_prepbuffer</code></a></h3><p> |
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6142 <span class="apii">[-?, +?, <em>e</em>]</span> |
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6143 <pre>char *luaL_prepbuffer (luaL_Buffer *B);</pre> |
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6144 |
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6145 <p> |
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6146 Equivalent to <a href="#luaL_prepbuffsize"><code>luaL_prepbuffsize</code></a> |
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6147 with the predefined size <a name="pdf-LUAL_BUFFERSIZE"><code>LUAL_BUFFERSIZE</code></a>. |
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6148 |
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6149 |
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6150 |
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6151 |
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6152 |
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6153 <hr><h3><a name="luaL_prepbuffsize"><code>luaL_prepbuffsize</code></a></h3><p> |
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6154 <span class="apii">[-?, +?, <em>e</em>]</span> |
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6155 <pre>char *luaL_prepbuffsize (luaL_Buffer *B, size_t sz);</pre> |
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6156 |
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6157 <p> |
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6158 Returns an address to a space of size <code>sz</code> |
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6159 where you can copy a string to be added to buffer <code>B</code> |
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6160 (see <a href="#luaL_Buffer"><code>luaL_Buffer</code></a>). |
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6161 After copying the string into this space you must call |
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6162 <a href="#luaL_addsize"><code>luaL_addsize</code></a> with the size of the string to actually add |
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6163 it to the buffer. |
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6164 |
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6165 |
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6166 |
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6167 |
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6168 |
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6169 <hr><h3><a name="luaL_pushresult"><code>luaL_pushresult</code></a></h3><p> |
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6170 <span class="apii">[-?, +1, <em>e</em>]</span> |
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6171 <pre>void luaL_pushresult (luaL_Buffer *B);</pre> |
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6172 |
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6173 <p> |
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6174 Finishes the use of buffer <code>B</code> leaving the final string on |
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6175 the top of the stack. |
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6176 |
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6177 |
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6178 |
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6179 |
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6180 |
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6181 <hr><h3><a name="luaL_pushresultsize"><code>luaL_pushresultsize</code></a></h3><p> |
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6182 <span class="apii">[-?, +1, <em>e</em>]</span> |
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6183 <pre>void luaL_pushresultsize (luaL_Buffer *B, size_t sz);</pre> |
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6184 |
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6185 <p> |
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6186 Equivalent to the sequence <a href="#luaL_addsize"><code>luaL_addsize</code></a>, <a href="#luaL_pushresult"><code>luaL_pushresult</code></a>. |
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6187 |
|
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|
6188 |
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|
6189 |
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|
6190 |
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6191 |
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6192 <hr><h3><a name="luaL_ref"><code>luaL_ref</code></a></h3><p> |
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6193 <span class="apii">[-1, +0, <em>e</em>]</span> |
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6194 <pre>int luaL_ref (lua_State *L, int t);</pre> |
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6195 |
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6196 <p> |
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6197 Creates and returns a <em>reference</em>, |
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6198 in the table at index <code>t</code>, |
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6199 for the object at the top of the stack (and pops the object). |
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6200 |
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|
6201 |
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6202 <p> |
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6203 A reference is a unique integer key. |
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6204 As long as you do not manually add integer keys into table <code>t</code>, |
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6205 <a href="#luaL_ref"><code>luaL_ref</code></a> ensures the uniqueness of the key it returns. |
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6206 You can retrieve an object referred by reference <code>r</code> |
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6207 by calling <code>lua_rawgeti(L, t, r)</code>. |
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6208 Function <a href="#luaL_unref"><code>luaL_unref</code></a> frees a reference and its associated object. |
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6209 |
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6210 |
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6211 <p> |
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6212 If the object at the top of the stack is <b>nil</b>, |
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6213 <a href="#luaL_ref"><code>luaL_ref</code></a> returns the constant <a name="pdf-LUA_REFNIL"><code>LUA_REFNIL</code></a>. |
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6214 The constant <a name="pdf-LUA_NOREF"><code>LUA_NOREF</code></a> is guaranteed to be different |
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6215 from any reference returned by <a href="#luaL_ref"><code>luaL_ref</code></a>. |
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6216 |
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6217 |
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6218 |
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6219 |
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6220 |
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6221 <hr><h3><a name="luaL_Reg"><code>luaL_Reg</code></a></h3> |
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6222 <pre>typedef struct luaL_Reg { |
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6223 const char *name; |
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6224 lua_CFunction func; |
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6225 } luaL_Reg;</pre> |
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6226 |
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6227 <p> |
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6228 Type for arrays of functions to be registered by |
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6229 <a href="#luaL_setfuncs"><code>luaL_setfuncs</code></a>. |
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6230 <code>name</code> is the function name and <code>func</code> is a pointer to |
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6231 the function. |
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|
6232 Any array of <a href="#luaL_Reg"><code>luaL_Reg</code></a> must end with a sentinel entry |
|
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|
6233 in which both <code>name</code> and <code>func</code> are <code>NULL</code>. |
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6234 |
|
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|
6235 |
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|
6236 |
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|
6237 |
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|
6238 |
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6239 <hr><h3><a name="luaL_requiref"><code>luaL_requiref</code></a></h3><p> |
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6240 <span class="apii">[-0, +1, <em>e</em>]</span> |
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6241 <pre>void luaL_requiref (lua_State *L, const char *modname, |
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|
6242 lua_CFunction openf, int glb);</pre> |
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6243 |
|
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6244 <p> |
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6245 If <code>modname</code> is not already present in <a href="#pdf-package.loaded"><code>package.loaded</code></a>, |
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|
6246 calls function <code>openf</code> with string <code>modname</code> as an argument |
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6247 and sets the call result in <code>package.loaded[modname]</code>, |
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6248 as if that function has been called through <a href="#pdf-require"><code>require</code></a>. |
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6249 |
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6250 |
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6251 <p> |
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6252 If <code>glb</code> is true, |
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6253 also stores the module into global <code>modname</code>. |
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6254 |
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|
6255 |
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6256 <p> |
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6257 Leaves a copy of the module on the stack. |
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6258 |
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|
6259 |
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|
6260 |
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|
6261 |
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|
6262 |
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6263 <hr><h3><a name="luaL_setfuncs"><code>luaL_setfuncs</code></a></h3><p> |
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6264 <span class="apii">[-nup, +0, <em>e</em>]</span> |
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6265 <pre>void luaL_setfuncs (lua_State *L, const luaL_Reg *l, int nup);</pre> |
|
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|
6266 |
|
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|
6267 <p> |
|
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|
6268 Registers all functions in the array <code>l</code> |
|
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|
6269 (see <a href="#luaL_Reg"><code>luaL_Reg</code></a>) into the table on the top of the stack |
|
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6270 (below optional upvalues, see next). |
|
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|
6271 |
|
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|
6272 |
|
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|
6273 <p> |
|
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|
6274 When <code>nup</code> is not zero, |
|
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|
6275 all functions are created sharing <code>nup</code> upvalues, |
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|
6276 which must be previously pushed on the stack |
|
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|
6277 on top of the library table. |
|
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|
6278 These values are popped from the stack after the registration. |
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|
6279 |
|
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|
6280 |
|
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|
6281 |
|
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|
6282 |
|
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|
6283 |
|
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|
6284 <hr><h3><a name="luaL_setmetatable"><code>luaL_setmetatable</code></a></h3><p> |
|
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6285 <span class="apii">[-0, +0, –]</span> |
|
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|
6286 <pre>void luaL_setmetatable (lua_State *L, const char *tname);</pre> |
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|
6287 |
|
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|
6288 <p> |
|
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|
6289 Sets the metatable of the object at the top of the stack |
|
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6290 as the metatable associated with name <code>tname</code> |
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|
6291 in the registry (see <a href="#luaL_newmetatable"><code>luaL_newmetatable</code></a>). |
|
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|
6292 |
|
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|
6293 |
|
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|
6294 |
|
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|
6295 |
|
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|
6296 |
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|
6297 <hr><h3><a name="luaL_Stream"><code>luaL_Stream</code></a></h3> |
|
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|
6298 <pre>typedef struct luaL_Stream { |
|
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|
6299 FILE *f; |
|
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|
6300 lua_CFunction closef; |
|
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|
6301 } luaL_Stream;</pre> |
|
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|
6302 |
|
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|
6303 <p> |
|
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|
6304 The standard representation for file handles, |
|
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|
6305 which is used by the standard I/O library. |
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|
6306 |
|
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|
6307 |
|
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|
6308 <p> |
|
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|
6309 A file handle is implemented as a full userdata, |
|
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|
6310 with a metatable called <code>LUA_FILEHANDLE</code> |
|
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|
6311 (where <code>LUA_FILEHANDLE</code> is a macro with the actual metatable's name). |
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6312 The metatable is created by the I/O library |
|
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|
6313 (see <a href="#luaL_newmetatable"><code>luaL_newmetatable</code></a>). |
|
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|
6314 |
|
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|
6315 |
|
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|
6316 <p> |
|
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|
6317 This userdata must start with the structure <code>luaL_Stream</code>; |
|
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6318 it can contain other data after this initial structure. |
|
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|
6319 Field <code>f</code> points to the corresponding C stream |
|
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6320 (or it can be <code>NULL</code> to indicate an incompletely created handle). |
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6321 Field <code>closef</code> points to a Lua function |
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6322 that will be called to close the stream |
|
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|
6323 when the handle is closed or collected; |
|
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6324 this function receives the file handle as its sole argument and |
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6325 must return either <b>true</b> (in case of success) |
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6326 or <b>nil</b> plus an error message (in case of error). |
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6327 Once Lua calls this field, |
|
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6328 the field value is changed to <code>NULL</code> |
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|
6329 to signal that the handle is closed. |
|
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|
6330 |
|
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changeset
|
6331 |
|
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|
6332 |
|
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|
6333 |
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|
6334 |
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|
6335 <hr><h3><a name="luaL_testudata"><code>luaL_testudata</code></a></h3><p> |
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6336 <span class="apii">[-0, +0, <em>e</em>]</span> |
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6337 <pre>void *luaL_testudata (lua_State *L, int arg, const char *tname);</pre> |
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|
6338 |
|
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|
6339 <p> |
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|
6340 This function works like <a href="#luaL_checkudata"><code>luaL_checkudata</code></a>, |
|
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6341 except that, when the test fails, |
|
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6342 it returns <code>NULL</code> instead of raising an error. |
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|
6343 |
|
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changeset
|
6344 |
|
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changeset
|
6345 |
|
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changeset
|
6346 |
|
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changeset
|
6347 |
|
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|
6348 <hr><h3><a name="luaL_tolstring"><code>luaL_tolstring</code></a></h3><p> |
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|
6349 <span class="apii">[-0, +1, <em>e</em>]</span> |
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|
6350 <pre>const char *luaL_tolstring (lua_State *L, int idx, size_t *len);</pre> |
|
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|
6351 |
|
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|
6352 <p> |
|
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|
6353 Converts any Lua value at the given index to a C string |
|
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|
6354 in a reasonable format. |
|
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|
6355 The resulting string is pushed onto the stack and also |
|
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|
6356 returned by the function. |
|
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|
6357 If <code>len</code> is not <code>NULL</code>, |
|
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|
6358 the function also sets <code>*len</code> with the string length. |
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|
6359 |
|
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|
6360 |
|
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|
6361 <p> |
|
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|
6362 If the value has a metatable with a <code>"__tostring"</code> field, |
|
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|
6363 then <code>luaL_tolstring</code> calls the corresponding metamethod |
|
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|
6364 with the value as argument, |
|
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|
6365 and uses the result of the call as its result. |
|
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|
6366 |
|
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|
6367 |
|
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|
6368 |
|
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|
6369 |
|
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|
6370 |
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|
6371 <hr><h3><a name="luaL_traceback"><code>luaL_traceback</code></a></h3><p> |
|
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6372 <span class="apii">[-0, +1, <em>e</em>]</span> |
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|
6373 <pre>void luaL_traceback (lua_State *L, lua_State *L1, const char *msg, |
|
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|
6374 int level);</pre> |
|
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|
6375 |
|
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|
6376 <p> |
|
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|
6377 Creates and pushes a traceback of the stack <code>L1</code>. |
|
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|
6378 If <code>msg</code> is not <code>NULL</code> it is appended |
|
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|
6379 at the beginning of the traceback. |
|
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|
6380 The <code>level</code> parameter tells at which level |
|
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|
6381 to start the traceback. |
|
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|
6382 |
|
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|
6383 |
|
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|
6384 |
|
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|
6385 |
|
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|
6386 |
|
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|
6387 <hr><h3><a name="luaL_typename"><code>luaL_typename</code></a></h3><p> |
|
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6388 <span class="apii">[-0, +0, –]</span> |
|
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|
6389 <pre>const char *luaL_typename (lua_State *L, int index);</pre> |
|
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|
6390 |
|
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|
6391 <p> |
|
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|
6392 Returns the name of the type of the value at the given index. |
|
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|
6393 |
|
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|
6394 |
|
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|
6395 |
|
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|
6396 |
|
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|
6397 |
|
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|
6398 <hr><h3><a name="luaL_unref"><code>luaL_unref</code></a></h3><p> |
|
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|
6399 <span class="apii">[-0, +0, –]</span> |
|
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|
6400 <pre>void luaL_unref (lua_State *L, int t, int ref);</pre> |
|
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|
6401 |
|
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|
6402 <p> |
|
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|
6403 Releases reference <code>ref</code> from the table at index <code>t</code> |
|
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|
6404 (see <a href="#luaL_ref"><code>luaL_ref</code></a>). |
|
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|
6405 The entry is removed from the table, |
|
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|
6406 so that the referred object can be collected. |
|
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|
6407 The reference <code>ref</code> is also freed to be used again. |
|
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|
6408 |
|
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|
6409 |
|
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|
6410 <p> |
|
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|
6411 If <code>ref</code> is <a href="#pdf-LUA_NOREF"><code>LUA_NOREF</code></a> or <a href="#pdf-LUA_REFNIL"><code>LUA_REFNIL</code></a>, |
|
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|
6412 <a href="#luaL_unref"><code>luaL_unref</code></a> does nothing. |
|
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|
6413 |
|
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|
6414 |
|
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|
6415 |
|
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|
6416 |
|
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|
6417 |
|
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|
6418 <hr><h3><a name="luaL_where"><code>luaL_where</code></a></h3><p> |
|
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6419 <span class="apii">[-0, +1, <em>e</em>]</span> |
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|
6420 <pre>void luaL_where (lua_State *L, int lvl);</pre> |
|
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|
6421 |
|
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|
6422 <p> |
|
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|
6423 Pushes onto the stack a string identifying the current position |
|
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|
6424 of the control at level <code>lvl</code> in the call stack. |
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|
6425 Typically this string has the following format: |
|
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|
6426 |
|
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|
6427 <pre> |
|
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|
6428 <em>chunkname</em>:<em>currentline</em>: |
|
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|
6429 </pre><p> |
|
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|
6430 Level 0 is the running function, |
|
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|
6431 level 1 is the function that called the running function, |
|
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|
6432 etc. |
|
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|
6433 |
|
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|
6434 |
|
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|
6435 <p> |
|
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|
6436 This function is used to build a prefix for error messages. |
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|
6437 |
|
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|
6438 |
|
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|
6439 |
|
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|
6440 |
|
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|
6441 |
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|
6442 |
|
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|
6443 |
|
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|
6444 <h1>6 – <a name="6">Standard Libraries</a></h1> |
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|
6445 |
|
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|
6446 <p> |
|
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|
6447 The standard Lua libraries provide useful functions |
|
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|
6448 that are implemented directly through the C API. |
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|
6449 Some of these functions provide essential services to the language |
|
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|
6450 (e.g., <a href="#pdf-type"><code>type</code></a> and <a href="#pdf-getmetatable"><code>getmetatable</code></a>); |
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|
6451 others provide access to "outside" services (e.g., I/O); |
|
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|
6452 and others could be implemented in Lua itself, |
|
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|
6453 but are quite useful or have critical performance requirements that |
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|
6454 deserve an implementation in C (e.g., <a href="#pdf-table.sort"><code>table.sort</code></a>). |
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|
6455 |
|
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|
6456 |
|
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|
6457 <p> |
|
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|
6458 All libraries are implemented through the official C API |
|
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|
6459 and are provided as separate C modules. |
|
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|
6460 Currently, Lua has the following standard libraries: |
|
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|
6461 |
|
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|
6462 <ul> |
|
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changeset
|
6463 |
|
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|
6464 <li>basic library (<a href="#6.1">§6.1</a>);</li> |
|
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|
6465 |
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|
6466 <li>coroutine library (<a href="#6.2">§6.2</a>);</li> |
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6467 |
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|
6468 <li>package library (<a href="#6.3">§6.3</a>);</li> |
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6469 |
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6470 <li>string manipulation (<a href="#6.4">§6.4</a>);</li> |
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6471 |
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6472 <li>basic UTF-8 support (<a href="#6.5">§6.5</a>);</li> |
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6473 |
|
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|
6474 <li>table manipulation (<a href="#6.6">§6.6</a>);</li> |
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6475 |
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6476 <li>mathematical functions (<a href="#6.7">§6.7</a>) (sin, log, etc.);</li> |
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6477 |
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6478 <li>input and output (<a href="#6.8">§6.8</a>);</li> |
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6479 |
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6480 <li>operating system facilities (<a href="#6.9">§6.9</a>);</li> |
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6481 |
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6482 <li>debug facilities (<a href="#6.10">§6.10</a>).</li> |
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6483 |
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|
6484 </ul><p> |
|
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6485 Except for the basic and the package libraries, |
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6486 each library provides all its functions as fields of a global table |
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6487 or as methods of its objects. |
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6488 |
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6489 |
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6490 <p> |
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|
6491 To have access to these libraries, |
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6492 the C host program should call the <a href="#luaL_openlibs"><code>luaL_openlibs</code></a> function, |
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6493 which opens all standard libraries. |
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6494 Alternatively, |
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6495 the host program can open them individually by using |
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6496 <a href="#luaL_requiref"><code>luaL_requiref</code></a> to call |
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|
6497 <a name="pdf-luaopen_base"><code>luaopen_base</code></a> (for the basic library), |
|
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|
6498 <a name="pdf-luaopen_package"><code>luaopen_package</code></a> (for the package library), |
|
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|
6499 <a name="pdf-luaopen_coroutine"><code>luaopen_coroutine</code></a> (for the coroutine library), |
|
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|
6500 <a name="pdf-luaopen_string"><code>luaopen_string</code></a> (for the string library), |
|
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6501 <a name="pdf-luaopen_utf8"><code>luaopen_utf8</code></a> (for the UTF8 library), |
|
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|
6502 <a name="pdf-luaopen_table"><code>luaopen_table</code></a> (for the table library), |
|
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|
6503 <a name="pdf-luaopen_math"><code>luaopen_math</code></a> (for the mathematical library), |
|
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6504 <a name="pdf-luaopen_io"><code>luaopen_io</code></a> (for the I/O library), |
|
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|
6505 <a name="pdf-luaopen_os"><code>luaopen_os</code></a> (for the operating system library), |
|
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6506 and <a name="pdf-luaopen_debug"><code>luaopen_debug</code></a> (for the debug library). |
|
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|
6507 These functions are declared in <a name="pdf-lualib.h"><code>lualib.h</code></a>. |
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6508 |
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6509 |
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6510 |
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|
6511 <h2>6.1 – <a name="6.1">Basic Functions</a></h2> |
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6512 |
|
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6513 <p> |
|
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6514 The basic library provides core functions to Lua. |
|
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6515 If you do not include this library in your application, |
|
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6516 you should check carefully whether you need to provide |
|
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6517 implementations for some of its facilities. |
|
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6518 |
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6519 |
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6520 <p> |
|
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|
6521 <hr><h3><a name="pdf-assert"><code>assert (v [, message])</code></a></h3> |
|
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6522 |
|
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6523 |
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|
6524 <p> |
|
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|
6525 Calls <a href="#pdf-error"><code>error</code></a> if |
|
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|
6526 the value of its argument <code>v</code> is false (i.e., <b>nil</b> or <b>false</b>); |
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6527 otherwise, returns all its arguments. |
|
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|
6528 In case of error, |
|
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|
6529 <code>message</code> is the error object; |
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|
6530 when absent, it defaults to "<code>assertion failed!</code>" |
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6531 |
|
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|
6532 |
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|
6533 |
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|
6534 |
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|
6535 <p> |
|
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|
6536 <hr><h3><a name="pdf-collectgarbage"><code>collectgarbage ([opt [, arg]])</code></a></h3> |
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6537 |
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6538 |
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6539 <p> |
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6540 This function is a generic interface to the garbage collector. |
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|
6541 It performs different functions according to its first argument, <code>opt</code>: |
|
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6542 |
|
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|
6543 <ul> |
|
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6544 |
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6545 <li><b>"<code>collect</code>": </b> |
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6546 performs a full garbage-collection cycle. |
|
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6547 This is the default option. |
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|
6548 </li> |
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6549 |
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6550 <li><b>"<code>stop</code>": </b> |
|
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|
6551 stops automatic execution of the garbage collector. |
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6552 The collector will run only when explicitly invoked, |
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6553 until a call to restart it. |
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6554 </li> |
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6555 |
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6556 <li><b>"<code>restart</code>": </b> |
|
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6557 restarts automatic execution of the garbage collector. |
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6558 </li> |
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6559 |
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6560 <li><b>"<code>count</code>": </b> |
|
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6561 returns the total memory in use by Lua in Kbytes. |
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6562 The value has a fractional part, |
|
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6563 so that it multiplied by 1024 |
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6564 gives the exact number of bytes in use by Lua |
|
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6565 (except for overflows). |
|
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|
6566 </li> |
|
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6567 |
|
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6568 <li><b>"<code>step</code>": </b> |
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|
6569 performs a garbage-collection step. |
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6570 The step "size" is controlled by <code>arg</code>. |
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6571 With a zero value, |
|
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6572 the collector will perform one basic (indivisible) step. |
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6573 For non-zero values, |
|
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|
6574 the collector will perform as if that amount of memory |
|
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6575 (in KBytes) had been allocated by Lua. |
|
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6576 Returns <b>true</b> if the step finished a collection cycle. |
|
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|
6577 </li> |
|
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|
6578 |
|
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|
6579 <li><b>"<code>setpause</code>": </b> |
|
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|
6580 sets <code>arg</code> as the new value for the <em>pause</em> of |
|
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|
6581 the collector (see <a href="#2.5">§2.5</a>). |
|
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|
6582 Returns the previous value for <em>pause</em>. |
|
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|
6583 </li> |
|
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|
6584 |
|
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|
6585 <li><b>"<code>setstepmul</code>": </b> |
|
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|
6586 sets <code>arg</code> as the new value for the <em>step multiplier</em> of |
|
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|
6587 the collector (see <a href="#2.5">§2.5</a>). |
|
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6588 Returns the previous value for <em>step</em>. |
|
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|
6589 </li> |
|
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|
6590 |
|
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|
6591 <li><b>"<code>isrunning</code>": </b> |
|
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|
6592 returns a boolean that tells whether the collector is running |
|
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6593 (i.e., not stopped). |
|
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|
6594 </li> |
|
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|
6595 |
|
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|
6596 </ul> |
|
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|
6597 |
|
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|
6598 |
|
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|
6599 |
|
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6600 <p> |
|
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|
6601 <hr><h3><a name="pdf-dofile"><code>dofile ([filename])</code></a></h3> |
|
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6602 Opens the named file and executes its contents as a Lua chunk. |
|
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6603 When called without arguments, |
|
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|
6604 <code>dofile</code> executes the contents of the standard input (<code>stdin</code>). |
|
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6605 Returns all values returned by the chunk. |
|
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|
6606 In case of errors, <code>dofile</code> propagates the error |
|
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|
6607 to its caller (that is, <code>dofile</code> does not run in protected mode). |
|
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|
6608 |
|
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|
6609 |
|
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|
6610 |
|
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|
6611 |
|
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|
6612 <p> |
|
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|
6613 <hr><h3><a name="pdf-error"><code>error (message [, level])</code></a></h3> |
|
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6614 Terminates the last protected function called |
|
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6615 and returns <code>message</code> as the error object. |
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6616 Function <code>error</code> never returns. |
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6617 |
|
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|
6618 |
|
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|
6619 <p> |
|
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6620 Usually, <code>error</code> adds some information about the error position |
|
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|
6621 at the beginning of the message, if the message is a string. |
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|
6622 The <code>level</code> argument specifies how to get the error position. |
|
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6623 With level 1 (the default), the error position is where the |
|
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6624 <code>error</code> function was called. |
|
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|
6625 Level 2 points the error to where the function |
|
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|
6626 that called <code>error</code> was called; and so on. |
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6627 Passing a level 0 avoids the addition of error position information |
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6628 to the message. |
|
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|
6629 |
|
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|
6630 |
|
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|
6631 |
|
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|
6632 |
|
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|
6633 <p> |
|
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|
6634 <hr><h3><a name="pdf-_G"><code>_G</code></a></h3> |
|
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|
6635 A global variable (not a function) that |
|
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|
6636 holds the global environment (see <a href="#2.2">§2.2</a>). |
|
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|
6637 Lua itself does not use this variable; |
|
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6638 changing its value does not affect any environment, |
|
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6639 nor vice versa. |
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|
6640 |
|
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|
6641 |
|
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|
6642 |
|
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|
6643 |
|
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|
6644 <p> |
|
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|
6645 <hr><h3><a name="pdf-getmetatable"><code>getmetatable (object)</code></a></h3> |
|
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|
6646 |
|
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|
6647 |
|
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|
6648 <p> |
|
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|
6649 If <code>object</code> does not have a metatable, returns <b>nil</b>. |
|
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|
6650 Otherwise, |
|
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|
6651 if the object's metatable has a <code>"__metatable"</code> field, |
|
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|
6652 returns the associated value. |
|
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|
6653 Otherwise, returns the metatable of the given object. |
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|
6654 |
|
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|
6655 |
|
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|
6656 |
|
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|
6657 |
|
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|
6658 <p> |
|
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|
6659 <hr><h3><a name="pdf-ipairs"><code>ipairs (t)</code></a></h3> |
|
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|
6660 |
|
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|
6661 |
|
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|
6662 <p> |
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|
6663 Returns three values (an iterator function, the table <code>t</code>, and 0) |
|
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|
6664 so that the construction |
|
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|
6665 |
|
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|
6666 <pre> |
|
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|
6667 for i,v in ipairs(t) do <em>body</em> end |
|
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|
6668 </pre><p> |
|
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|
6669 will iterate over the key–value pairs |
|
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6670 (<code>1,t[1]</code>), (<code>2,t[2]</code>), ..., |
|
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|
6671 up to the first nil value. |
|
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|
6672 |
|
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|
6673 |
|
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|
6674 |
|
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changeset
|
6675 |
|
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|
6676 <p> |
|
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|
6677 <hr><h3><a name="pdf-load"><code>load (chunk [, chunkname [, mode [, env]]])</code></a></h3> |
|
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|
6678 |
|
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changeset
|
6679 |
|
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|
6680 <p> |
|
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|
6681 Loads a chunk. |
|
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changeset
|
6682 |
|
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changeset
|
6683 |
|
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|
6684 <p> |
|
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|
6685 If <code>chunk</code> is a string, the chunk is this string. |
|
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|
6686 If <code>chunk</code> is a function, |
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6687 <code>load</code> calls it repeatedly to get the chunk pieces. |
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|
6688 Each call to <code>chunk</code> must return a string that concatenates |
|
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|
6689 with previous results. |
|
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|
6690 A return of an empty string, <b>nil</b>, or no value signals the end of the chunk. |
|
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changeset
|
6691 |
|
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changeset
|
6692 |
|
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changeset
|
6693 <p> |
|
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changeset
|
6694 If there are no syntactic errors, |
|
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changeset
|
6695 returns the compiled chunk as a function; |
|
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|
6696 otherwise, returns <b>nil</b> plus the error message. |
|
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|
6697 |
|
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|
6698 |
|
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|
6699 <p> |
|
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|
6700 If the resulting function has upvalues, |
|
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|
6701 the first upvalue is set to the value of <code>env</code>, |
|
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6702 if that parameter is given, |
|
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|
6703 or to the value of the global environment. |
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|
6704 Other upvalues are initialized with <b>nil</b>. |
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|
6705 (When you load a main chunk, |
|
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|
6706 the resulting function will always have exactly one upvalue, |
|
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|
6707 the <code>_ENV</code> variable (see <a href="#2.2">§2.2</a>). |
|
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6708 However, |
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|
6709 when you load a binary chunk created from a function (see <a href="#pdf-string.dump"><code>string.dump</code></a>), |
|
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|
6710 the resulting function can have an arbitrary number of upvalues.) |
|
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|
6711 All upvalues are fresh, that is, |
|
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6712 they are not shared with any other function. |
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6713 |
|
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|
6714 |
|
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|
6715 <p> |
|
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|
6716 <code>chunkname</code> is used as the name of the chunk for error messages |
|
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|
6717 and debug information (see <a href="#4.9">§4.9</a>). |
|
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|
6718 When absent, |
|
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|
6719 it defaults to <code>chunk</code>, if <code>chunk</code> is a string, |
|
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6720 or to "<code>=(load)</code>" otherwise. |
|
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|
6721 |
|
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|
6722 |
|
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|
6723 <p> |
|
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|
6724 The string <code>mode</code> controls whether the chunk can be text or binary |
|
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|
6725 (that is, a precompiled chunk). |
|
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|
6726 It may be the string "<code>b</code>" (only binary chunks), |
|
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|
6727 "<code>t</code>" (only text chunks), |
|
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|
6728 or "<code>bt</code>" (both binary and text). |
|
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|
6729 The default is "<code>bt</code>". |
|
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|
6730 |
|
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|
6731 |
|
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|
6732 <p> |
|
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|
6733 Lua does not check the consistency of binary chunks. |
|
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|
6734 Maliciously crafted binary chunks can crash |
|
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|
6735 the interpreter. |
|
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|
6736 |
|
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changeset
|
6737 |
|
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changeset
|
6738 |
|
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|
6739 |
|
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|
6740 <p> |
|
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|
6741 <hr><h3><a name="pdf-loadfile"><code>loadfile ([filename [, mode [, env]]])</code></a></h3> |
|
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|
6742 |
|
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|
6743 |
|
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|
6744 <p> |
|
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|
6745 Similar to <a href="#pdf-load"><code>load</code></a>, |
|
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|
6746 but gets the chunk from file <code>filename</code> |
|
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6747 or from the standard input, |
|
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|
6748 if no file name is given. |
|
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|
6749 |
|
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|
6750 |
|
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|
6751 |
|
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|
6752 |
|
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|
6753 <p> |
|
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|
6754 <hr><h3><a name="pdf-next"><code>next (table [, index])</code></a></h3> |
|
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|
6755 |
|
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|
6756 |
|
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|
6757 <p> |
|
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|
6758 Allows a program to traverse all fields of a table. |
|
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|
6759 Its first argument is a table and its second argument |
|
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6760 is an index in this table. |
|
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|
6761 <code>next</code> returns the next index of the table |
|
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|
6762 and its associated value. |
|
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|
6763 When called with <b>nil</b> as its second argument, |
|
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|
6764 <code>next</code> returns an initial index |
|
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|
6765 and its associated value. |
|
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|
6766 When called with the last index, |
|
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|
6767 or with <b>nil</b> in an empty table, |
|
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|
6768 <code>next</code> returns <b>nil</b>. |
|
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|
6769 If the second argument is absent, then it is interpreted as <b>nil</b>. |
|
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|
6770 In particular, |
|
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|
6771 you can use <code>next(t)</code> to check whether a table is empty. |
|
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|
6772 |
|
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|
6773 |
|
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|
6774 <p> |
|
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|
6775 The order in which the indices are enumerated is not specified, |
|
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6776 <em>even for numeric indices</em>. |
|
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|
6777 (To traverse a table in numeric order, |
|
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|
6778 use a numerical <b>for</b>.) |
|
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|
6779 |
|
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|
6780 |
|
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|
6781 <p> |
|
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|
6782 The behavior of <code>next</code> is undefined if, |
|
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6783 during the traversal, |
|
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|
6784 you assign any value to a non-existent field in the table. |
|
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|
6785 You may however modify existing fields. |
|
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|
6786 In particular, you may clear existing fields. |
|
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|
6787 |
|
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changeset
|
6788 |
|
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|
6789 |
|
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changeset
|
6790 |
|
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|
6791 <p> |
|
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|
6792 <hr><h3><a name="pdf-pairs"><code>pairs (t)</code></a></h3> |
|
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|
6793 |
|
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|
6794 |
|
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|
6795 <p> |
|
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|
6796 If <code>t</code> has a metamethod <code>__pairs</code>, |
|
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|
6797 calls it with <code>t</code> as argument and returns the first three |
|
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|
6798 results from the call. |
|
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|
6799 |
|
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|
6800 |
|
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|
6801 <p> |
|
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|
6802 Otherwise, |
|
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|
6803 returns three values: the <a href="#pdf-next"><code>next</code></a> function, the table <code>t</code>, and <b>nil</b>, |
|
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|
6804 so that the construction |
|
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|
6805 |
|
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|
6806 <pre> |
|
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|
6807 for k,v in pairs(t) do <em>body</em> end |
|
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|
6808 </pre><p> |
|
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|
6809 will iterate over all key–value pairs of table <code>t</code>. |
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|
6810 |
|
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|
6811 |
|
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|
6812 <p> |
|
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|
6813 See function <a href="#pdf-next"><code>next</code></a> for the caveats of modifying |
|
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|
6814 the table during its traversal. |
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|
6815 |
|
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diff
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|
6816 |
|
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diff
changeset
|
6817 |
|
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|
6818 |
|
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|
6819 <p> |
|
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|
6820 <hr><h3><a name="pdf-pcall"><code>pcall (f [, arg1, ···])</code></a></h3> |
|
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|
6821 |
|
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|
6822 |
|
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|
6823 <p> |
|
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6824 Calls function <code>f</code> with |
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|
6825 the given arguments in <em>protected mode</em>. |
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|
6826 This means that any error inside <code>f</code> is not propagated; |
|
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|
6827 instead, <code>pcall</code> catches the error |
|
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|
6828 and returns a status code. |
|
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|
6829 Its first result is the status code (a boolean), |
|
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diff
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|
6830 which is true if the call succeeds without errors. |
|
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|
6831 In such case, <code>pcall</code> also returns all results from the call, |
|
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6832 after this first result. |
|
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|
6833 In case of any error, <code>pcall</code> returns <b>false</b> plus the error message. |
|
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|
6834 |
|
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diff
changeset
|
6835 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
6836 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
6837 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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|
6838 <p> |
|
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|
6839 <hr><h3><a name="pdf-print"><code>print (···)</code></a></h3> |
|
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|
6840 Receives any number of arguments |
|
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|
6841 and prints their values to <code>stdout</code>, |
|
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|
6842 using the <a href="#pdf-tostring"><code>tostring</code></a> function to convert each argument to a string. |
|
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diff
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|
6843 <code>print</code> is not intended for formatted output, |
|
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diff
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|
6844 but only as a quick way to show a value, |
|
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changeset
|
6845 for instance for debugging. |
|
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diff
changeset
|
6846 For complete control over the output, |
|
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diff
changeset
|
6847 use <a href="#pdf-string.format"><code>string.format</code></a> and <a href="#pdf-io.write"><code>io.write</code></a>. |
|
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changeset
|
6848 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
6849 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
6850 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
6851 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
6852 <p> |
|
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|
6853 <hr><h3><a name="pdf-rawequal"><code>rawequal (v1, v2)</code></a></h3> |
|
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|
6854 Checks whether <code>v1</code> is equal to <code>v2</code>, |
|
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changeset
|
6855 without invoking any metamethod. |
|
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parents:
diff
changeset
|
6856 Returns a boolean. |
|
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parents:
diff
changeset
|
6857 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
6858 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
6859 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
6860 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
6861 <p> |
|
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|
6862 <hr><h3><a name="pdf-rawget"><code>rawget (table, index)</code></a></h3> |
|
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|
6863 Gets the real value of <code>table[index]</code>, |
|
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changeset
|
6864 without invoking any metamethod. |
|
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parents:
diff
changeset
|
6865 <code>table</code> must be a table; |
|
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|
6866 <code>index</code> may be any value. |
|
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changeset
|
6867 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
6868 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
6869 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
6870 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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|
6871 <p> |
|
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|
6872 <hr><h3><a name="pdf-rawlen"><code>rawlen (v)</code></a></h3> |
|
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|
6873 Returns the length of the object <code>v</code>, |
|
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changeset
|
6874 which must be a table or a string, |
|
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diff
changeset
|
6875 without invoking any metamethod. |
|
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diff
changeset
|
6876 Returns an integer. |
|
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diff
changeset
|
6877 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
6878 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
6879 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
6880 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
6881 <p> |
|
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diff
changeset
|
6882 <hr><h3><a name="pdf-rawset"><code>rawset (table, index, value)</code></a></h3> |
|
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|
6883 Sets the real value of <code>table[index]</code> to <code>value</code>, |
|
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parents:
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changeset
|
6884 without invoking any metamethod. |
|
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parents:
diff
changeset
|
6885 <code>table</code> must be a table, |
|
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changeset
|
6886 <code>index</code> any value different from <b>nil</b> and NaN, |
|
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diff
changeset
|
6887 and <code>value</code> any Lua value. |
|
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parents:
diff
changeset
|
6888 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
6889 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
6890 <p> |
|
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parents:
diff
changeset
|
6891 This function returns <code>table</code>. |
|
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parents:
diff
changeset
|
6892 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
6893 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
6894 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
6895 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
6896 <p> |
|
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diff
changeset
|
6897 <hr><h3><a name="pdf-select"><code>select (index, ···)</code></a></h3> |
|
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parents:
diff
changeset
|
6898 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
6899 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
6900 <p> |
|
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diff
changeset
|
6901 If <code>index</code> is a number, |
|
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changeset
|
6902 returns all arguments after argument number <code>index</code>; |
|
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parents:
diff
changeset
|
6903 a negative number indexes from the end (-1 is the last argument). |
|
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parents:
diff
changeset
|
6904 Otherwise, <code>index</code> must be the string <code>"#"</code>, |
|
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changeset
|
6905 and <code>select</code> returns the total number of extra arguments it received. |
|
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parents:
diff
changeset
|
6906 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
6907 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
6908 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
6909 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
6910 <p> |
|
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changeset
|
6911 <hr><h3><a name="pdf-setmetatable"><code>setmetatable (table, metatable)</code></a></h3> |
|
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diff
changeset
|
6912 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
6913 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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changeset
|
6914 <p> |
|
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changeset
|
6915 Sets the metatable for the given table. |
|
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diff
changeset
|
6916 (You cannot change the metatable of other types from Lua, only from C.) |
|
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changeset
|
6917 If <code>metatable</code> is <b>nil</b>, |
|
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changeset
|
6918 removes the metatable of the given table. |
|
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diff
changeset
|
6919 If the original metatable has a <code>"__metatable"</code> field, |
|
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changeset
|
6920 raises an error. |
|
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parents:
diff
changeset
|
6921 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
6922 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
6923 <p> |
|
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parents:
diff
changeset
|
6924 This function returns <code>table</code>. |
|
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parents:
diff
changeset
|
6925 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
6926 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
6927 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
6928 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
6929 <p> |
|
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changeset
|
6930 <hr><h3><a name="pdf-tonumber"><code>tonumber (e [, base])</code></a></h3> |
|
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parents:
diff
changeset
|
6931 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
6932 |
|
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|
6933 <p> |
|
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|
6934 When called with no <code>base</code>, |
|
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|
6935 <code>tonumber</code> tries to convert its argument to a number. |
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|
6936 If the argument is already a number or |
|
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|
6937 a string convertible to a number, |
|
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|
6938 then <code>tonumber</code> returns this number; |
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|
6939 otherwise, it returns <b>nil</b>. |
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|
6940 |
|
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|
6941 |
|
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|
6942 <p> |
|
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diff
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|
6943 The conversion of strings can result in integers or floats, |
|
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|
6944 according to the lexical conventions of Lua (see <a href="#3.1">§3.1</a>). |
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6945 (The string may have leading and trailing spaces and a sign.) |
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|
6946 |
|
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|
6947 |
|
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|
6948 <p> |
|
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|
6949 When called with <code>base</code>, |
|
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|
6950 then <code>e</code> must be a string to be interpreted as |
|
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|
6951 an integer numeral in that base. |
|
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6952 The base may be any integer between 2 and 36, inclusive. |
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6953 In bases above 10, the letter '<code>A</code>' (in either upper or lower case) |
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|
6954 represents 10, '<code>B</code>' represents 11, and so forth, |
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|
6955 with '<code>Z</code>' representing 35. |
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|
6956 If the string <code>e</code> is not a valid numeral in the given base, |
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6957 the function returns <b>nil</b>. |
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|
6958 |
|
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|
6959 |
|
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|
6960 |
|
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|
6961 |
|
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|
6962 <p> |
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|
6963 <hr><h3><a name="pdf-tostring"><code>tostring (v)</code></a></h3> |
|
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6964 Receives a value of any type and |
|
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6965 converts it to a string in a human-readable format. |
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|
6966 Floats always produce strings with some |
|
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|
6967 floating-point indication (either a decimal dot or an exponent). |
|
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6968 (For complete control of how numbers are converted, |
|
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|
6969 use <a href="#pdf-string.format"><code>string.format</code></a>.) |
|
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|
6970 |
|
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diff
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|
6971 |
|
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|
6972 <p> |
|
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|
6973 If the metatable of <code>v</code> has a <code>"__tostring"</code> field, |
|
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|
6974 then <code>tostring</code> calls the corresponding value |
|
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|
6975 with <code>v</code> as argument, |
|
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|
6976 and uses the result of the call as its result. |
|
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|
6977 |
|
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diff
changeset
|
6978 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
6979 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
6980 |
|
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|
6981 <p> |
|
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|
6982 <hr><h3><a name="pdf-type"><code>type (v)</code></a></h3> |
|
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|
6983 Returns the type of its only argument, coded as a string. |
|
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|
6984 The possible results of this function are |
|
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|
6985 "<code>nil</code>" (a string, not the value <b>nil</b>), |
|
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|
6986 "<code>number</code>", |
|
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|
6987 "<code>string</code>", |
|
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|
6988 "<code>boolean</code>", |
|
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|
6989 "<code>table</code>", |
|
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|
6990 "<code>function</code>", |
|
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|
6991 "<code>thread</code>", |
|
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|
6992 and "<code>userdata</code>". |
|
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|
6993 |
|
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diff
changeset
|
6994 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
6995 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
6996 |
|
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|
6997 <p> |
|
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|
6998 <hr><h3><a name="pdf-_VERSION"><code>_VERSION</code></a></h3> |
|
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|
6999 A global variable (not a function) that |
|
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diff
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|
7000 holds a string containing the current interpreter version. |
|
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diff
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|
7001 The current value of this variable is "<code>Lua 5.3</code>". |
|
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|
7002 |
|
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parents:
diff
changeset
|
7003 |
|
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parents:
diff
changeset
|
7004 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7005 |
|
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parents:
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|
7006 <p> |
|
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parents:
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|
7007 <hr><h3><a name="pdf-xpcall"><code>xpcall (f, msgh [, arg1, ···])</code></a></h3> |
|
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|
7008 |
|
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changeset
|
7009 |
|
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|
7010 <p> |
|
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|
7011 This function is similar to <a href="#pdf-pcall"><code>pcall</code></a>, |
|
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|
7012 except that it sets a new message handler <code>msgh</code>. |
|
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|
7013 |
|
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parents:
diff
changeset
|
7014 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7015 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7016 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7017 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7018 |
|
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changeset
|
7019 |
|
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changeset
|
7020 <h2>6.2 – <a name="6.2">Coroutine Manipulation</a></h2> |
|
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changeset
|
7021 |
|
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changeset
|
7022 <p> |
|
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changeset
|
7023 The operations related to coroutines comprise a sub-library of |
|
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|
7024 the basic library and come inside the table <a name="pdf-coroutine"><code>coroutine</code></a>. |
|
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|
7025 See <a href="#2.6">§2.6</a> for a general description of coroutines. |
|
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changeset
|
7026 |
|
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parents:
diff
changeset
|
7027 |
|
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changeset
|
7028 <p> |
|
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|
7029 <hr><h3><a name="pdf-coroutine.create"><code>coroutine.create (f)</code></a></h3> |
|
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changeset
|
7030 |
|
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parents:
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changeset
|
7031 |
|
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changeset
|
7032 <p> |
|
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changeset
|
7033 Creates a new coroutine, with body <code>f</code>. |
|
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changeset
|
7034 <code>f</code> must be a Lua function. |
|
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changeset
|
7035 Returns this new coroutine, |
|
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changeset
|
7036 an object with type <code>"thread"</code>. |
|
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changeset
|
7037 |
|
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diff
changeset
|
7038 |
|
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parents:
diff
changeset
|
7039 |
|
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parents:
diff
changeset
|
7040 |
|
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changeset
|
7041 <p> |
|
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changeset
|
7042 <hr><h3><a name="pdf-coroutine.isyieldable"><code>coroutine.isyieldable ()</code></a></h3> |
|
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changeset
|
7043 |
|
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changeset
|
7044 |
|
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changeset
|
7045 <p> |
|
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changeset
|
7046 Returns true when the running coroutine can yield. |
|
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changeset
|
7047 |
|
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changeset
|
7048 |
|
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changeset
|
7049 <p> |
|
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changeset
|
7050 A running coroutine is yieldable if it is not the main thread and |
|
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diff
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|
7051 it is not inside a non-yieldable C function. |
|
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|
7052 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7053 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7054 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7055 |
|
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diff
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|
7056 <p> |
|
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diff
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|
7057 <hr><h3><a name="pdf-coroutine.resume"><code>coroutine.resume (co [, val1, ···])</code></a></h3> |
|
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|
7058 |
|
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parents:
diff
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|
7059 |
|
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diff
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|
7060 <p> |
|
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diff
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|
7061 Starts or continues the execution of coroutine <code>co</code>. |
|
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|
7062 The first time you resume a coroutine, |
|
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diff
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|
7063 it starts running its body. |
|
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|
7064 The values <code>val1</code>, ... are passed |
|
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parents:
diff
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|
7065 as the arguments to the body function. |
|
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parents:
diff
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|
7066 If the coroutine has yielded, |
|
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parents:
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|
7067 <code>resume</code> restarts it; |
|
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parents:
diff
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|
7068 the values <code>val1</code>, ... are passed |
|
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parents:
diff
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|
7069 as the results from the yield. |
|
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diff
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|
7070 |
|
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diff
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|
7071 |
|
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diff
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|
7072 <p> |
|
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diff
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|
7073 If the coroutine runs without any errors, |
|
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parents:
diff
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|
7074 <code>resume</code> returns <b>true</b> plus any values passed to <code>yield</code> |
|
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|
7075 (when the coroutine yields) or any values returned by the body function |
|
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|
7076 (when the coroutine terminates). |
|
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parents:
diff
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|
7077 If there is any error, |
|
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|
7078 <code>resume</code> returns <b>false</b> plus the error message. |
|
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|
7079 |
|
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diff
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|
7080 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7081 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
7082 |
|
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|
7083 <p> |
|
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|
7084 <hr><h3><a name="pdf-coroutine.running"><code>coroutine.running ()</code></a></h3> |
|
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|
7085 |
|
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diff
changeset
|
7086 |
|
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|
7087 <p> |
|
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diff
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|
7088 Returns the running coroutine plus a boolean, |
|
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|
7089 true when the running coroutine is the main one. |
|
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diff
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|
7090 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7091 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7092 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7093 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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|
7094 <p> |
|
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|
7095 <hr><h3><a name="pdf-coroutine.status"><code>coroutine.status (co)</code></a></h3> |
|
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|
7096 |
|
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diff
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|
7097 |
|
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|
7098 <p> |
|
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|
7099 Returns the status of coroutine <code>co</code>, as a string: |
|
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parents:
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|
7100 <code>"running"</code>, |
|
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|
7101 if the coroutine is running (that is, it called <code>status</code>); |
|
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|
7102 <code>"suspended"</code>, if the coroutine is suspended in a call to <code>yield</code>, |
|
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|
7103 or if it has not started running yet; |
|
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|
7104 <code>"normal"</code> if the coroutine is active but not running |
|
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|
7105 (that is, it has resumed another coroutine); |
|
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|
7106 and <code>"dead"</code> if the coroutine has finished its body function, |
|
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|
7107 or if it has stopped with an error. |
|
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|
7108 |
|
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diff
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|
7109 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
7110 |
|
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parents:
diff
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|
7111 |
|
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|
7112 <p> |
|
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|
7113 <hr><h3><a name="pdf-coroutine.wrap"><code>coroutine.wrap (f)</code></a></h3> |
|
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|
7114 |
|
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parents:
diff
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|
7115 |
|
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|
7116 <p> |
|
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|
7117 Creates a new coroutine, with body <code>f</code>. |
|
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|
7118 <code>f</code> must be a Lua function. |
|
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|
7119 Returns a function that resumes the coroutine each time it is called. |
|
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parents:
diff
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|
7120 Any arguments passed to the function behave as the |
|
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parents:
diff
changeset
|
7121 extra arguments to <code>resume</code>. |
|
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parents:
diff
changeset
|
7122 Returns the same values returned by <code>resume</code>, |
|
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parents:
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|
7123 except the first boolean. |
|
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parents:
diff
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|
7124 In case of error, propagates the error. |
|
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parents:
diff
changeset
|
7125 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7126 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7127 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7128 |
|
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parents:
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|
7129 <p> |
|
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parents:
diff
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|
7130 <hr><h3><a name="pdf-coroutine.yield"><code>coroutine.yield (···)</code></a></h3> |
|
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parents:
diff
changeset
|
7131 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7132 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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|
7133 <p> |
|
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parents:
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|
7134 Suspends the execution of the calling coroutine. |
|
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parents:
diff
changeset
|
7135 Any arguments to <code>yield</code> are passed as extra results to <code>resume</code>. |
|
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parents:
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changeset
|
7136 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7137 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7138 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7139 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7140 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7141 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7142 |
|
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parents:
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|
7143 <h2>6.3 – <a name="6.3">Modules</a></h2> |
|
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parents:
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changeset
|
7144 |
|
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parents:
diff
changeset
|
7145 <p> |
|
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parents:
diff
changeset
|
7146 The package library provides basic |
|
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parents:
diff
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|
7147 facilities for loading modules in Lua. |
|
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diff
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|
7148 It exports one function directly in the global environment: |
|
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|
7149 <a href="#pdf-require"><code>require</code></a>. |
|
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changeset
|
7150 Everything else is exported in a table <a name="pdf-package"><code>package</code></a>. |
|
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changeset
|
7151 |
|
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changeset
|
7152 |
|
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|
7153 <p> |
|
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changeset
|
7154 <hr><h3><a name="pdf-require"><code>require (modname)</code></a></h3> |
|
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parents:
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changeset
|
7155 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7156 |
|
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parents:
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changeset
|
7157 <p> |
|
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parents:
diff
changeset
|
7158 Loads the given module. |
|
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parents:
diff
changeset
|
7159 The function starts by looking into the <a href="#pdf-package.loaded"><code>package.loaded</code></a> table |
|
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diff
changeset
|
7160 to determine whether <code>modname</code> is already loaded. |
|
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parents:
diff
changeset
|
7161 If it is, then <code>require</code> returns the value stored |
|
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parents:
diff
changeset
|
7162 at <code>package.loaded[modname]</code>. |
|
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parents:
diff
changeset
|
7163 Otherwise, it tries to find a <em>loader</em> for the module. |
|
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parents:
diff
changeset
|
7164 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7165 |
|
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parents:
diff
changeset
|
7166 <p> |
|
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changeset
|
7167 To find a loader, |
|
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parents:
diff
changeset
|
7168 <code>require</code> is guided by the <a href="#pdf-package.searchers"><code>package.searchers</code></a> sequence. |
|
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parents:
diff
changeset
|
7169 By changing this sequence, |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
7170 we can change how <code>require</code> looks for a module. |
|
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parents:
diff
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|
7171 The following explanation is based on the default configuration |
|
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parents:
diff
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|
7172 for <a href="#pdf-package.searchers"><code>package.searchers</code></a>. |
|
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parents:
diff
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|
7173 |
|
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parents:
diff
changeset
|
7174 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
7175 <p> |
|
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parents:
diff
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|
7176 First <code>require</code> queries <code>package.preload[modname]</code>. |
|
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parents:
diff
changeset
|
7177 If it has a value, |
|
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parents:
diff
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|
7178 this value (which must be a function) is the loader. |
|
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parents:
diff
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|
7179 Otherwise <code>require</code> searches for a Lua loader using the |
|
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parents:
diff
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|
7180 path stored in <a href="#pdf-package.path"><code>package.path</code></a>. |
|
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parents:
diff
changeset
|
7181 If that also fails, it searches for a C loader using the |
|
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parents:
diff
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|
7182 path stored in <a href="#pdf-package.cpath"><code>package.cpath</code></a>. |
|
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parents:
diff
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|
7183 If that also fails, |
|
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parents:
diff
changeset
|
7184 it tries an <em>all-in-one</em> loader (see <a href="#pdf-package.searchers"><code>package.searchers</code></a>). |
|
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diff
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|
7185 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7186 |
|
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parents:
diff
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|
7187 <p> |
|
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parents:
diff
changeset
|
7188 Once a loader is found, |
|
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parents:
diff
changeset
|
7189 <code>require</code> calls the loader with two arguments: |
|
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parents:
diff
changeset
|
7190 <code>modname</code> and an extra value dependent on how it got the loader. |
|
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parents:
diff
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|
7191 (If the loader came from a file, |
|
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parents:
diff
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|
7192 this extra value is the file name.) |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7193 If the loader returns any non-nil value, |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7194 <code>require</code> assigns the returned value to <code>package.loaded[modname]</code>. |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7195 If the loader does not return a non-nil value and |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
7196 has not assigned any value to <code>package.loaded[modname]</code>, |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7197 then <code>require</code> assigns <b>true</b> to this entry. |
|
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parents:
diff
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|
7198 In any case, <code>require</code> returns the |
|
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parents:
diff
changeset
|
7199 final value of <code>package.loaded[modname]</code>. |
|
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parents:
diff
changeset
|
7200 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7201 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
7202 <p> |
|
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parents:
diff
changeset
|
7203 If there is any error loading or running the module, |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
7204 or if it cannot find any loader for the module, |
|
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parents:
diff
changeset
|
7205 then <code>require</code> raises an error. |
|
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parents:
diff
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|
7206 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7207 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7208 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7209 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
7210 <p> |
|
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diff
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|
7211 <hr><h3><a name="pdf-package.config"><code>package.config</code></a></h3> |
|
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diff
changeset
|
7212 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7213 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
7214 <p> |
|
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parents:
diff
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|
7215 A string describing some compile-time configurations for packages. |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
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|
7216 This string is a sequence of lines: |
|
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parents:
diff
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|
7217 |
|
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parents:
diff
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|
7218 <ul> |
|
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diff
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|
7219 |
|
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|
7220 <li>The first line is the directory separator string. |
|
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parents:
diff
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|
7221 Default is '<code>\</code>' for Windows and '<code>/</code>' for all other systems.</li> |
|
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diff
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|
7222 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
7223 <li>The second line is the character that separates templates in a path. |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
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|
7224 Default is '<code>;</code>'.</li> |
|
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parents:
diff
changeset
|
7225 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7226 <li>The third line is the string that marks the |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7227 substitution points in a template. |
|
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parents:
diff
changeset
|
7228 Default is '<code>?</code>'.</li> |
|
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diff
changeset
|
7229 |
|
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parents:
diff
changeset
|
7230 <li>The fourth line is a string that, in a path in Windows, |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7231 is replaced by the executable's directory. |
|
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parents:
diff
changeset
|
7232 Default is '<code>!</code>'.</li> |
|
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parents:
diff
changeset
|
7233 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
7234 <li>The fifth line is a mark to ignore all text after it |
|
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parents:
diff
changeset
|
7235 when building the <code>luaopen_</code> function name. |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
7236 Default is '<code>-</code>'.</li> |
|
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parents:
diff
changeset
|
7237 |
|
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parents:
diff
changeset
|
7238 </ul> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7239 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7240 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7241 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
7242 <p> |
|
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parents:
diff
changeset
|
7243 <hr><h3><a name="pdf-package.cpath"><code>package.cpath</code></a></h3> |
|
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parents:
diff
changeset
|
7244 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7245 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
7246 <p> |
|
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parents:
diff
changeset
|
7247 The path used by <a href="#pdf-require"><code>require</code></a> to search for a C loader. |
|
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parents:
diff
changeset
|
7248 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7249 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7250 <p> |
|
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parents:
diff
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|
7251 Lua initializes the C path <a href="#pdf-package.cpath"><code>package.cpath</code></a> in the same way |
|
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diff
changeset
|
7252 it initializes the Lua path <a href="#pdf-package.path"><code>package.path</code></a>, |
|
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diff
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|
7253 using the environment variable <a name="pdf-LUA_CPATH_5_3"><code>LUA_CPATH_5_3</code></a> |
|
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parents:
diff
changeset
|
7254 or the environment variable <a name="pdf-LUA_CPATH"><code>LUA_CPATH</code></a> |
|
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parents:
diff
changeset
|
7255 or a default path defined in <code>luaconf.h</code>. |
|
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parents:
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changeset
|
7256 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7257 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7258 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7259 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7260 <p> |
|
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parents:
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changeset
|
7261 <hr><h3><a name="pdf-package.loaded"><code>package.loaded</code></a></h3> |
|
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changeset
|
7262 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7263 |
|
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parents:
diff
changeset
|
7264 <p> |
|
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diff
changeset
|
7265 A table used by <a href="#pdf-require"><code>require</code></a> to control which |
|
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changeset
|
7266 modules are already loaded. |
|
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parents:
diff
changeset
|
7267 When you require a module <code>modname</code> and |
|
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diff
changeset
|
7268 <code>package.loaded[modname]</code> is not false, |
|
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parents:
diff
changeset
|
7269 <a href="#pdf-require"><code>require</code></a> simply returns the value stored there. |
|
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parents:
diff
changeset
|
7270 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7271 |
|
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|
7272 <p> |
|
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changeset
|
7273 This variable is only a reference to the real table; |
|
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parents:
diff
changeset
|
7274 assignments to this variable do not change the |
|
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parents:
diff
changeset
|
7275 table used by <a href="#pdf-require"><code>require</code></a>. |
|
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parents:
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changeset
|
7276 |
|
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parents:
diff
changeset
|
7277 |
|
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parents:
diff
changeset
|
7278 |
|
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parents:
diff
changeset
|
7279 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7280 <p> |
|
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parents:
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changeset
|
7281 <hr><h3><a name="pdf-package.loadlib"><code>package.loadlib (libname, funcname)</code></a></h3> |
|
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parents:
diff
changeset
|
7282 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7283 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7284 <p> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7285 Dynamically links the host program with the C library <code>libname</code>. |
|
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parents:
diff
changeset
|
7286 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7287 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7288 <p> |
|
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parents:
diff
changeset
|
7289 If <code>funcname</code> is "<code>*</code>", |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7290 then it only links with the library, |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7291 making the symbols exported by the library |
|
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parents:
diff
changeset
|
7292 available to other dynamically linked libraries. |
|
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parents:
diff
changeset
|
7293 Otherwise, |
|
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parents:
diff
changeset
|
7294 it looks for a function <code>funcname</code> inside the library |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
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|
7295 and returns this function as a C function. |
|
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parents:
diff
changeset
|
7296 So, <code>funcname</code> must follow the <a href="#lua_CFunction"><code>lua_CFunction</code></a> prototype |
|
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parents:
diff
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|
7297 (see <a href="#lua_CFunction"><code>lua_CFunction</code></a>). |
|
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parents:
diff
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|
7298 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7299 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7300 <p> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7301 This is a low-level function. |
|
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parents:
diff
changeset
|
7302 It completely bypasses the package and module system. |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
7303 Unlike <a href="#pdf-require"><code>require</code></a>, |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
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|
7304 it does not perform any path searching and |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
7305 does not automatically adds extensions. |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
7306 <code>libname</code> must be the complete file name of the C library, |
|
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parents:
diff
changeset
|
7307 including if necessary a path and an extension. |
|
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parents:
diff
changeset
|
7308 <code>funcname</code> must be the exact name exported by the C library |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
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|
7309 (which may depend on the C compiler and linker used). |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7310 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7311 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
7312 <p> |
|
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parents:
diff
changeset
|
7313 This function is not supported by Standard C. |
|
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parents:
diff
changeset
|
7314 As such, it is only available on some platforms |
|
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parents:
diff
changeset
|
7315 (Windows, Linux, Mac OS X, Solaris, BSD, |
|
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parents:
diff
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|
7316 plus other Unix systems that support the <code>dlfcn</code> standard). |
|
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parents:
diff
changeset
|
7317 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7318 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7319 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7320 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
7321 <p> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
7322 <hr><h3><a name="pdf-package.path"><code>package.path</code></a></h3> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7323 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7324 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
7325 <p> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7326 The path used by <a href="#pdf-require"><code>require</code></a> to search for a Lua loader. |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7327 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7328 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
7329 <p> |
|
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parents:
diff
changeset
|
7330 At start-up, Lua initializes this variable with |
|
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parents:
diff
changeset
|
7331 the value of the environment variable <a name="pdf-LUA_PATH_5_3"><code>LUA_PATH_5_3</code></a> or |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
7332 the environment variable <a name="pdf-LUA_PATH"><code>LUA_PATH</code></a> or |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7333 with a default path defined in <code>luaconf.h</code>, |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7334 if those environment variables are not defined. |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7335 Any "<code>;;</code>" in the value of the environment variable |
|
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parents:
diff
changeset
|
7336 is replaced by the default path. |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7337 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7338 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7339 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7340 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7341 <p> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
7342 <hr><h3><a name="pdf-package.preload"><code>package.preload</code></a></h3> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
7343 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7344 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
7345 <p> |
|
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parents:
diff
changeset
|
7346 A table to store loaders for specific modules |
|
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parents:
diff
changeset
|
7347 (see <a href="#pdf-require"><code>require</code></a>). |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7348 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7349 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7350 <p> |
|
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parents:
diff
changeset
|
7351 This variable is only a reference to the real table; |
|
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parents:
diff
changeset
|
7352 assignments to this variable do not change the |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7353 table used by <a href="#pdf-require"><code>require</code></a>. |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7354 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7355 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7356 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7357 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7358 <p> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7359 <hr><h3><a name="pdf-package.searchers"><code>package.searchers</code></a></h3> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7360 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7361 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7362 <p> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7363 A table used by <a href="#pdf-require"><code>require</code></a> to control how to load modules. |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7364 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7365 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7366 <p> |
|
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parents:
diff
changeset
|
7367 Each entry in this table is a <em>searcher function</em>. |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7368 When looking for a module, |
|
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parents:
diff
changeset
|
7369 <a href="#pdf-require"><code>require</code></a> calls each of these searchers in ascending order, |
|
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parents:
diff
changeset
|
7370 with the module name (the argument given to <a href="#pdf-require"><code>require</code></a>) as its |
|
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parents:
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changeset
|
7371 sole parameter. |
|
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parents:
diff
changeset
|
7372 The function can return another function (the module <em>loader</em>) |
|
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parents:
diff
changeset
|
7373 plus an extra value that will be passed to that loader, |
|
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parents:
diff
changeset
|
7374 or a string explaining why it did not find that module |
|
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parents:
diff
changeset
|
7375 (or <b>nil</b> if it has nothing to say). |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7376 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7377 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7378 <p> |
|
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parents:
diff
changeset
|
7379 Lua initializes this table with four searcher functions. |
|
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parents:
diff
changeset
|
7380 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7381 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7382 <p> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7383 The first searcher simply looks for a loader in the |
|
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parents:
diff
changeset
|
7384 <a href="#pdf-package.preload"><code>package.preload</code></a> table. |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7385 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7386 |
|
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parents:
diff
changeset
|
7387 <p> |
|
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parents:
diff
changeset
|
7388 The second searcher looks for a loader as a Lua library, |
|
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parents:
diff
changeset
|
7389 using the path stored at <a href="#pdf-package.path"><code>package.path</code></a>. |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7390 The search is done as described in function <a href="#pdf-package.searchpath"><code>package.searchpath</code></a>. |
|
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parents:
diff
changeset
|
7391 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7392 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7393 <p> |
|
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parents:
diff
changeset
|
7394 The third searcher looks for a loader as a C library, |
|
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parents:
diff
changeset
|
7395 using the path given by the variable <a href="#pdf-package.cpath"><code>package.cpath</code></a>. |
|
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parents:
diff
changeset
|
7396 Again, |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7397 the search is done as described in function <a href="#pdf-package.searchpath"><code>package.searchpath</code></a>. |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7398 For instance, |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7399 if the C path is the string |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7400 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7401 <pre> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
7402 "./?.so;./?.dll;/usr/local/?/init.so" |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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|
7403 </pre><p> |
|
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diff
changeset
|
7404 the searcher for module <code>foo</code> |
|
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parents:
diff
changeset
|
7405 will try to open the files <code>./foo.so</code>, <code>./foo.dll</code>, |
|
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parents:
diff
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|
7406 and <code>/usr/local/foo/init.so</code>, in that order. |
|
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changeset
|
7407 Once it finds a C library, |
|
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parents:
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|
7408 this searcher first uses a dynamic link facility to link the |
|
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|
7409 application with the library. |
|
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parents:
diff
changeset
|
7410 Then it tries to find a C function inside the library to |
|
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parents:
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|
7411 be used as the loader. |
|
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|
7412 The name of this C function is the string "<code>luaopen_</code>" |
|
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|
7413 concatenated with a copy of the module name where each dot |
|
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parents:
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|
7414 is replaced by an underscore. |
|
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|
7415 Moreover, if the module name has a hyphen, |
|
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parents:
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|
7416 its suffix after (and including) the first hyphen is removed. |
|
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|
7417 For instance, if the module name is <code>a.b.c-v2.1</code>, |
|
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|
7418 the function name will be <code>luaopen_a_b_c</code>. |
|
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|
7419 |
|
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diff
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|
7420 |
|
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|
7421 <p> |
|
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|
7422 The fourth searcher tries an <em>all-in-one loader</em>. |
|
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|
7423 It searches the C path for a library for |
|
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|
7424 the root name of the given module. |
|
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diff
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|
7425 For instance, when requiring <code>a.b.c</code>, |
|
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parents:
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|
7426 it will search for a C library for <code>a</code>. |
|
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parents:
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|
7427 If found, it looks into it for an open function for |
|
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parents:
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|
7428 the submodule; |
|
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parents:
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|
7429 in our example, that would be <code>luaopen_a_b_c</code>. |
|
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parents:
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|
7430 With this facility, a package can pack several C submodules |
|
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parents:
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|
7431 into one single library, |
|
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diff
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|
7432 with each submodule keeping its original open function. |
|
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parents:
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|
7433 |
|
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parents:
diff
changeset
|
7434 |
|
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|
7435 <p> |
|
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|
7436 All searchers except the first one (preload) return as the extra value |
|
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|
7437 the file name where the module was found, |
|
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parents:
diff
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|
7438 as returned by <a href="#pdf-package.searchpath"><code>package.searchpath</code></a>. |
|
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|
7439 The first searcher returns no extra value. |
|
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|
7440 |
|
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diff
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|
7441 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7442 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7443 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
7444 <p> |
|
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diff
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|
7445 <hr><h3><a name="pdf-package.searchpath"><code>package.searchpath (name, path [, sep [, rep]])</code></a></h3> |
|
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|
7446 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
7447 |
|
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|
7448 <p> |
|
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|
7449 Searches for the given <code>name</code> in the given <code>path</code>. |
|
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|
7450 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
7451 |
|
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parents:
diff
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|
7452 <p> |
|
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|
7453 A path is a string containing a sequence of |
|
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parents:
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|
7454 <em>templates</em> separated by semicolons. |
|
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|
7455 For each template, |
|
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|
7456 the function replaces each interrogation mark (if any) |
|
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parents:
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|
7457 in the template with a copy of <code>name</code> |
|
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parents:
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|
7458 wherein all occurrences of <code>sep</code> |
|
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parents:
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|
7459 (a dot, by default) |
|
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|
7460 were replaced by <code>rep</code> |
|
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parents:
diff
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|
7461 (the system's directory separator, by default), |
|
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parents:
diff
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|
7462 and then tries to open the resulting file name. |
|
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parents:
diff
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|
7463 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7464 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
7465 <p> |
|
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parents:
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|
7466 For instance, if the path is the string |
|
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parents:
diff
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|
7467 |
|
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diff
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|
7468 <pre> |
|
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diff
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|
7469 "./?.lua;./?.lc;/usr/local/?/init.lua" |
|
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changeset
|
7470 </pre><p> |
|
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|
7471 the search for the name <code>foo.a</code> |
|
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parents:
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changeset
|
7472 will try to open the files |
|
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parents:
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changeset
|
7473 <code>./foo/a.lua</code>, <code>./foo/a.lc</code>, and |
|
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parents:
diff
changeset
|
7474 <code>/usr/local/foo/a/init.lua</code>, in that order. |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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changeset
|
7475 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7476 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
7477 <p> |
|
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parents:
diff
changeset
|
7478 Returns the resulting name of the first file that it can |
|
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parents:
diff
changeset
|
7479 open in read mode (after closing the file), |
|
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parents:
diff
changeset
|
7480 or <b>nil</b> plus an error message if none succeeds. |
|
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parents:
diff
changeset
|
7481 (This error message lists all file names it tried to open.) |
|
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parents:
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changeset
|
7482 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7483 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7484 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7485 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7486 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7487 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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changeset
|
7488 |
|
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|
7489 <h2>6.4 – <a name="6.4">String Manipulation</a></h2> |
|
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changeset
|
7490 |
|
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changeset
|
7491 <p> |
|
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parents:
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changeset
|
7492 This library provides generic functions for string manipulation, |
|
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parents:
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|
7493 such as finding and extracting substrings, and pattern matching. |
|
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parents:
diff
changeset
|
7494 When indexing a string in Lua, the first character is at position 1 |
|
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parents:
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changeset
|
7495 (not at 0, as in C). |
|
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parents:
diff
changeset
|
7496 Indices are allowed to be negative and are interpreted as indexing backwards, |
|
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parents:
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changeset
|
7497 from the end of the string. |
|
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diff
changeset
|
7498 Thus, the last character is at position -1, and so on. |
|
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parents:
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changeset
|
7499 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7500 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7501 <p> |
|
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parents:
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changeset
|
7502 The string library provides all its functions inside the table |
|
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changeset
|
7503 <a name="pdf-string"><code>string</code></a>. |
|
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|
7504 It also sets a metatable for strings |
|
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changeset
|
7505 where the <code>__index</code> field points to the <code>string</code> table. |
|
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changeset
|
7506 Therefore, you can use the string functions in object-oriented style. |
|
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changeset
|
7507 For instance, <code>string.byte(s,i)</code> |
|
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parents:
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changeset
|
7508 can be written as <code>s:byte(i)</code>. |
|
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changeset
|
7509 |
|
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changeset
|
7510 |
|
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changeset
|
7511 <p> |
|
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parents:
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changeset
|
7512 The string library assumes one-byte character encodings. |
|
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parents:
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changeset
|
7513 |
|
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parents:
diff
changeset
|
7514 |
|
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parents:
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changeset
|
7515 <p> |
|
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changeset
|
7516 <hr><h3><a name="pdf-string.byte"><code>string.byte (s [, i [, j]])</code></a></h3> |
|
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changeset
|
7517 Returns the internal numerical codes of the characters <code>s[i]</code>, |
|
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changeset
|
7518 <code>s[i+1]</code>, ..., <code>s[j]</code>. |
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|
7519 The default value for <code>i</code> is 1; |
|
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|
7520 the default value for <code>j</code> is <code>i</code>. |
|
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|
7521 These indices are corrected |
|
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|
7522 following the same rules of function <a href="#pdf-string.sub"><code>string.sub</code></a>. |
|
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|
7523 |
|
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|
7524 |
|
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|
7525 <p> |
|
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|
7526 Numerical codes are not necessarily portable across platforms. |
|
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|
7527 |
|
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diff
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|
7528 |
|
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|
7529 |
|
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|
7530 |
|
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|
7531 <p> |
|
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|
7532 <hr><h3><a name="pdf-string.char"><code>string.char (···)</code></a></h3> |
|
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|
7533 Receives zero or more integers. |
|
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|
7534 Returns a string with length equal to the number of arguments, |
|
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|
7535 in which each character has the internal numerical code equal |
|
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|
7536 to its corresponding argument. |
|
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|
7537 |
|
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|
7538 |
|
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|
7539 <p> |
|
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|
7540 Numerical codes are not necessarily portable across platforms. |
|
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|
7541 |
|
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diff
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|
7542 |
|
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diff
changeset
|
7543 |
|
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|
7544 |
|
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|
7545 <p> |
|
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|
7546 <hr><h3><a name="pdf-string.dump"><code>string.dump (function [, strip])</code></a></h3> |
|
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|
7547 |
|
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|
7548 |
|
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|
7549 <p> |
|
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|
7550 Returns a string containing a binary representation |
|
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|
7551 (a <em>binary chunk</em>) |
|
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|
7552 of the given function, |
|
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|
7553 so that a later <a href="#pdf-load"><code>load</code></a> on this string returns |
|
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|
7554 a copy of the function (but with new upvalues). |
|
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|
7555 If <code>strip</code> is a true value, |
|
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|
7556 the binary representation is created without debug information |
|
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|
7557 about the function |
|
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|
7558 (local variable names, lines, etc.). |
|
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diff
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|
7559 |
|
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diff
changeset
|
7560 |
|
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|
7561 <p> |
|
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changeset
|
7562 Functions with upvalues have only their number of upvalues saved. |
|
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|
7563 When (re)loaded, |
|
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|
7564 those upvalues receive fresh instances containing <b>nil</b>. |
|
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|
7565 (You can use the debug library to serialize |
|
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|
7566 and reload the upvalues of a function |
|
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|
7567 in a way adequate to your needs.) |
|
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changeset
|
7568 |
|
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diff
changeset
|
7569 |
|
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diff
changeset
|
7570 |
|
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diff
changeset
|
7571 |
|
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|
7572 <p> |
|
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|
7573 <hr><h3><a name="pdf-string.find"><code>string.find (s, pattern [, init [, plain]])</code></a></h3> |
|
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|
7574 |
|
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|
7575 |
|
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|
7576 <p> |
|
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|
7577 Looks for the first match of |
|
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|
7578 <code>pattern</code> (see <a href="#6.4.1">§6.4.1</a>) in the string <code>s</code>. |
|
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|
7579 If it finds a match, then <code>find</code> returns the indices of <code>s</code> |
|
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|
7580 where this occurrence starts and ends; |
|
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|
7581 otherwise, it returns <b>nil</b>. |
|
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|
7582 A third, optional numerical argument <code>init</code> specifies |
|
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|
7583 where to start the search; |
|
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|
7584 its default value is 1 and can be negative. |
|
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|
7585 A value of <b>true</b> as a fourth, optional argument <code>plain</code> |
|
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|
7586 turns off the pattern matching facilities, |
|
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|
7587 so the function does a plain "find substring" operation, |
|
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changeset
|
7588 with no characters in <code>pattern</code> being considered magic. |
|
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|
7589 Note that if <code>plain</code> is given, then <code>init</code> must be given as well. |
|
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changeset
|
7590 |
|
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changeset
|
7591 |
|
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changeset
|
7592 <p> |
|
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changeset
|
7593 If the pattern has captures, |
|
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changeset
|
7594 then in a successful match |
|
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changeset
|
7595 the captured values are also returned, |
|
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changeset
|
7596 after the two indices. |
|
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changeset
|
7597 |
|
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diff
changeset
|
7598 |
|
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diff
changeset
|
7599 |
|
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changeset
|
7600 |
|
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changeset
|
7601 <p> |
|
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|
7602 <hr><h3><a name="pdf-string.format"><code>string.format (formatstring, ···)</code></a></h3> |
|
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|
7603 |
|
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changeset
|
7604 |
|
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|
7605 <p> |
|
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|
7606 Returns a formatted version of its variable number of arguments |
|
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|
7607 following the description given in its first argument (which must be a string). |
|
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|
7608 The format string follows the same rules as the ISO C function <code>sprintf</code>. |
|
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|
7609 The only differences are that the options/modifiers |
|
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|
7610 <code>*</code>, <code>h</code>, <code>L</code>, <code>l</code>, <code>n</code>, |
|
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|
7611 and <code>p</code> are not supported |
|
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|
7612 and that there is an extra option, <code>q</code>. |
|
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|
7613 The <code>q</code> option formats a string between double quotes, |
|
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|
7614 using escape sequences when necessary to ensure that |
|
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|
7615 it can safely be read back by the Lua interpreter. |
|
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|
7616 For instance, the call |
|
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|
7617 |
|
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|
7618 <pre> |
|
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changeset
|
7619 string.format('%q', 'a string with "quotes" and \n new line') |
|
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|
7620 </pre><p> |
|
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|
7621 may produce the string: |
|
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changeset
|
7622 |
|
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changeset
|
7623 <pre> |
|
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changeset
|
7624 "a string with \"quotes\" and \ |
|
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|
7625 new line" |
|
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changeset
|
7626 </pre> |
|
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changeset
|
7627 |
|
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changeset
|
7628 <p> |
|
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changeset
|
7629 Options |
|
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changeset
|
7630 <code>A</code> and <code>a</code> (when available), |
|
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|
7631 <code>E</code>, <code>e</code>, <code>f</code>, |
|
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|
7632 <code>G</code>, and <code>g</code> all expect a number as argument. |
|
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|
7633 Options <code>c</code>, <code>d</code>, |
|
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|
7634 <code>i</code>, <code>o</code>, <code>u</code>, <code>X</code>, and <code>x</code> |
|
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changeset
|
7635 expect an integer. |
|
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|
7636 Option <code>q</code> expects a string; |
|
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|
7637 option <code>s</code> expects a string without embedded zeros. |
|
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|
7638 If the argument to option <code>s</code> is not a string, |
|
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|
7639 it is converted to one following the same rules of <a href="#pdf-tostring"><code>tostring</code></a>. |
|
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|
7640 |
|
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diff
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|
7641 |
|
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diff
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|
7642 |
|
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|
7643 |
|
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|
7644 <p> |
|
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|
7645 <hr><h3><a name="pdf-string.gmatch"><code>string.gmatch (s, pattern)</code></a></h3> |
|
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|
7646 Returns an iterator function that, |
|
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|
7647 each time it is called, |
|
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|
7648 returns the next captures from <code>pattern</code> (see <a href="#6.4.1">§6.4.1</a>) |
|
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|
7649 over the string <code>s</code>. |
|
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|
7650 If <code>pattern</code> specifies no captures, |
|
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|
7651 then the whole match is produced in each call. |
|
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|
7652 |
|
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|
7653 |
|
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|
7654 <p> |
|
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|
7655 As an example, the following loop |
|
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|
7656 will iterate over all the words from string <code>s</code>, |
|
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|
7657 printing one per line: |
|
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|
7658 |
|
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|
7659 <pre> |
|
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|
7660 s = "hello world from Lua" |
|
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|
7661 for w in string.gmatch(s, "%a+") do |
|
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|
7662 print(w) |
|
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|
7663 end |
|
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|
7664 </pre><p> |
|
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|
7665 The next example collects all pairs <code>key=value</code> from the |
|
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|
7666 given string into a table: |
|
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|
7667 |
|
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|
7668 <pre> |
|
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|
7669 t = {} |
|
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|
7670 s = "from=world, to=Lua" |
|
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|
7671 for k, v in string.gmatch(s, "(%w+)=(%w+)") do |
|
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|
7672 t[k] = v |
|
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|
7673 end |
|
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|
7674 </pre> |
|
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|
7675 |
|
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|
7676 <p> |
|
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|
7677 For this function, a caret '<code>^</code>' at the start of a pattern does not |
|
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|
7678 work as an anchor, as this would prevent the iteration. |
|
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|
7679 |
|
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|
7680 |
|
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changeset
|
7681 |
|
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changeset
|
7682 |
|
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|
7683 <p> |
|
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|
7684 <hr><h3><a name="pdf-string.gsub"><code>string.gsub (s, pattern, repl [, n])</code></a></h3> |
|
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|
7685 Returns a copy of <code>s</code> |
|
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|
7686 in which all (or the first <code>n</code>, if given) |
|
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|
7687 occurrences of the <code>pattern</code> (see <a href="#6.4.1">§6.4.1</a>) have been |
|
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|
7688 replaced by a replacement string specified by <code>repl</code>, |
|
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|
7689 which can be a string, a table, or a function. |
|
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|
7690 <code>gsub</code> also returns, as its second value, |
|
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|
7691 the total number of matches that occurred. |
|
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|
7692 The name <code>gsub</code> comes from <em>Global SUBstitution</em>. |
|
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|
7693 |
|
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|
7694 |
|
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|
7695 <p> |
|
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|
7696 If <code>repl</code> is a string, then its value is used for replacement. |
|
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|
7697 The character <code>%</code> works as an escape character: |
|
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|
7698 any sequence in <code>repl</code> of the form <code>%<em>d</em></code>, |
|
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|
7699 with <em>d</em> between 1 and 9, |
|
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|
7700 stands for the value of the <em>d</em>-th captured substring. |
|
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|
7701 The sequence <code>%0</code> stands for the whole match. |
|
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|
7702 The sequence <code>%%</code> stands for a single <code>%</code>. |
|
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|
7703 |
|
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diff
changeset
|
7704 |
|
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|
7705 <p> |
|
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|
7706 If <code>repl</code> is a table, then the table is queried for every match, |
|
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|
7707 using the first capture as the key. |
|
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|
7708 |
|
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diff
changeset
|
7709 |
|
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|
7710 <p> |
|
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|
7711 If <code>repl</code> is a function, then this function is called every time a |
|
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|
7712 match occurs, with all captured substrings passed as arguments, |
|
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|
7713 in order. |
|
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parents:
diff
changeset
|
7714 |
|
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diff
changeset
|
7715 |
|
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|
7716 <p> |
|
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changeset
|
7717 In any case, |
|
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|
7718 if the pattern specifies no captures, |
|
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changeset
|
7719 then it behaves as if the whole pattern was inside a capture. |
|
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changeset
|
7720 |
|
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diff
changeset
|
7721 |
|
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|
7722 <p> |
|
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changeset
|
7723 If the value returned by the table query or by the function call |
|
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|
7724 is a string or a number, |
|
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changeset
|
7725 then it is used as the replacement string; |
|
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|
7726 otherwise, if it is <b>false</b> or <b>nil</b>, |
|
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changeset
|
7727 then there is no replacement |
|
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changeset
|
7728 (that is, the original match is kept in the string). |
|
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changeset
|
7729 |
|
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changeset
|
7730 |
|
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|
7731 <p> |
|
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changeset
|
7732 Here are some examples: |
|
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changeset
|
7733 |
|
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changeset
|
7734 <pre> |
|
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changeset
|
7735 x = string.gsub("hello world", "(%w+)", "%1 %1") |
|
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|
7736 --> x="hello hello world world" |
|
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changeset
|
7737 |
|
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changeset
|
7738 x = string.gsub("hello world", "%w+", "%0 %0", 1) |
|
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changeset
|
7739 --> x="hello hello world" |
|
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changeset
|
7740 |
|
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changeset
|
7741 x = string.gsub("hello world from Lua", "(%w+)%s*(%w+)", "%2 %1") |
|
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|
7742 --> x="world hello Lua from" |
|
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changeset
|
7743 |
|
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|
7744 x = string.gsub("home = $HOME, user = $USER", "%$(%w+)", os.getenv) |
|
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changeset
|
7745 --> x="home = /home/roberto, user = roberto" |
|
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changeset
|
7746 |
|
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|
7747 x = string.gsub("4+5 = $return 4+5$", "%$(.-)%$", function (s) |
|
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changeset
|
7748 return load(s)() |
|
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changeset
|
7749 end) |
|
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changeset
|
7750 --> x="4+5 = 9" |
|
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changeset
|
7751 |
|
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changeset
|
7752 local t = {name="lua", version="5.3"} |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7753 x = string.gsub("$name-$version.tar.gz", "%$(%w+)", t) |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
7754 --> x="lua-5.3.tar.gz" |
|
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diff
changeset
|
7755 </pre> |
|
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parents:
diff
changeset
|
7756 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7757 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7758 |
|
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parents:
diff
changeset
|
7759 <p> |
|
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parents:
diff
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|
7760 <hr><h3><a name="pdf-string.len"><code>string.len (s)</code></a></h3> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
7761 Receives a string and returns its length. |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
7762 The empty string <code>""</code> has length 0. |
|
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parents:
diff
changeset
|
7763 Embedded zeros are counted, |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
7764 so <code>"a\000bc\000"</code> has length 5. |
|
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parents:
diff
changeset
|
7765 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7766 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7767 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7768 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7769 <p> |
|
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diff
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|
7770 <hr><h3><a name="pdf-string.lower"><code>string.lower (s)</code></a></h3> |
|
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parents:
diff
changeset
|
7771 Receives a string and returns a copy of this string with all |
|
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parents:
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|
7772 uppercase letters changed to lowercase. |
|
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|
7773 All other characters are left unchanged. |
|
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parents:
diff
changeset
|
7774 The definition of what an uppercase letter is depends on the current locale. |
|
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|
7775 |
|
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diff
changeset
|
7776 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7777 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7778 |
|
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diff
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|
7779 <p> |
|
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|
7780 <hr><h3><a name="pdf-string.match"><code>string.match (s, pattern [, init])</code></a></h3> |
|
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parents:
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|
7781 Looks for the first <em>match</em> of |
|
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diff
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|
7782 <code>pattern</code> (see <a href="#6.4.1">§6.4.1</a>) in the string <code>s</code>. |
|
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|
7783 If it finds one, then <code>match</code> returns |
|
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|
7784 the captures from the pattern; |
|
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parents:
diff
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|
7785 otherwise it returns <b>nil</b>. |
|
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parents:
diff
changeset
|
7786 If <code>pattern</code> specifies no captures, |
|
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parents:
diff
changeset
|
7787 then the whole match is returned. |
|
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diff
changeset
|
7788 A third, optional numerical argument <code>init</code> specifies |
|
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changeset
|
7789 where to start the search; |
|
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diff
changeset
|
7790 its default value is 1 and can be negative. |
|
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diff
changeset
|
7791 |
|
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parents:
diff
changeset
|
7792 |
|
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parents:
diff
changeset
|
7793 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7794 |
|
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diff
changeset
|
7795 <p> |
|
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parents:
diff
changeset
|
7796 <hr><h3><a name="pdf-string.pack"><code>string.pack (fmt, v1, v2, ···)</code></a></h3> |
|
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diff
changeset
|
7797 |
|
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parents:
diff
changeset
|
7798 |
|
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diff
changeset
|
7799 <p> |
|
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diff
changeset
|
7800 Returns a binary string containing the values <code>v1</code>, <code>v2</code>, etc. |
|
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diff
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|
7801 packed (that is, serialized in binary form) |
|
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|
7802 according to the format string <code>fmt</code> (see <a href="#6.4.2">§6.4.2</a>). |
|
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changeset
|
7803 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7804 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7805 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7806 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7807 <p> |
|
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diff
changeset
|
7808 <hr><h3><a name="pdf-string.packsize"><code>string.packsize (fmt)</code></a></h3> |
|
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diff
changeset
|
7809 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7810 |
|
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parents:
diff
changeset
|
7811 <p> |
|
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diff
changeset
|
7812 Returns the size of a string resulting from <a href="#pdf-string.pack"><code>string.pack</code></a> |
|
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changeset
|
7813 with the given format. |
|
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parents:
diff
changeset
|
7814 The format string cannot have the variable-length options |
|
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diff
changeset
|
7815 '<code>s</code>' or '<code>z</code>' (see <a href="#6.4.2">§6.4.2</a>). |
|
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changeset
|
7816 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7817 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7818 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7819 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
7820 <p> |
|
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parents:
diff
changeset
|
7821 <hr><h3><a name="pdf-string.rep"><code>string.rep (s, n [, sep])</code></a></h3> |
|
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parents:
diff
changeset
|
7822 Returns a string that is the concatenation of <code>n</code> copies of |
|
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parents:
diff
changeset
|
7823 the string <code>s</code> separated by the string <code>sep</code>. |
|
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parents:
diff
changeset
|
7824 The default value for <code>sep</code> is the empty string |
|
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parents:
diff
changeset
|
7825 (that is, no separator). |
|
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parents:
diff
changeset
|
7826 Returns the empty string if <code>n</code> is not positive. |
|
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parents:
diff
changeset
|
7827 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7828 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7829 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7830 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7831 <p> |
|
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parents:
diff
changeset
|
7832 <hr><h3><a name="pdf-string.reverse"><code>string.reverse (s)</code></a></h3> |
|
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parents:
diff
changeset
|
7833 Returns a string that is the string <code>s</code> reversed. |
|
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parents:
diff
changeset
|
7834 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7835 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7836 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7837 |
|
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parents:
diff
changeset
|
7838 <p> |
|
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parents:
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changeset
|
7839 <hr><h3><a name="pdf-string.sub"><code>string.sub (s, i [, j])</code></a></h3> |
|
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parents:
diff
changeset
|
7840 Returns the substring of <code>s</code> that |
|
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parents:
diff
changeset
|
7841 starts at <code>i</code> and continues until <code>j</code>; |
|
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changeset
|
7842 <code>i</code> and <code>j</code> can be negative. |
|
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diff
changeset
|
7843 If <code>j</code> is absent, then it is assumed to be equal to -1 |
|
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diff
changeset
|
7844 (which is the same as the string length). |
|
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parents:
diff
changeset
|
7845 In particular, |
|
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parents:
diff
changeset
|
7846 the call <code>string.sub(s,1,j)</code> returns a prefix of <code>s</code> |
|
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parents:
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changeset
|
7847 with length <code>j</code>, |
|
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parents:
diff
changeset
|
7848 and <code>string.sub(s, -i)</code> returns a suffix of <code>s</code> |
|
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changeset
|
7849 with length <code>i</code>. |
|
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parents:
diff
changeset
|
7850 |
|
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parents:
diff
changeset
|
7851 |
|
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parents:
diff
changeset
|
7852 <p> |
|
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changeset
|
7853 If, after the translation of negative indices, |
|
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parents:
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changeset
|
7854 <code>i</code> is less than 1, |
|
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|
7855 it is corrected to 1. |
|
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diff
changeset
|
7856 If <code>j</code> is greater than the string length, |
|
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changeset
|
7857 it is corrected to that length. |
|
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diff
changeset
|
7858 If, after these corrections, |
|
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diff
changeset
|
7859 <code>i</code> is greater than <code>j</code>, |
|
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changeset
|
7860 the function returns the empty string. |
|
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diff
changeset
|
7861 |
|
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parents:
diff
changeset
|
7862 |
|
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parents:
diff
changeset
|
7863 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7864 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7865 <p> |
|
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parents:
diff
changeset
|
7866 <hr><h3><a name="pdf-string.unpack"><code>string.unpack (fmt, s [, pos])</code></a></h3> |
|
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changeset
|
7867 |
|
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parents:
diff
changeset
|
7868 |
|
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|
7869 <p> |
|
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|
7870 Returns the values packed in string <code>s</code> (see <a href="#pdf-string.pack"><code>string.pack</code></a>) |
|
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7871 according to the format string <code>fmt</code> (see <a href="#6.4.2">§6.4.2</a>). |
|
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7872 An optional <code>pos</code> marks where |
|
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|
7873 to start reading in <code>s</code> (default is 1). |
|
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7874 After the read values, |
|
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|
7875 this function also returns the index of the first unread byte in <code>s</code>. |
|
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|
7876 |
|
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|
7877 |
|
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|
7878 |
|
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|
7879 |
|
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|
7880 <p> |
|
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|
7881 <hr><h3><a name="pdf-string.upper"><code>string.upper (s)</code></a></h3> |
|
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7882 Receives a string and returns a copy of this string with all |
|
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7883 lowercase letters changed to uppercase. |
|
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7884 All other characters are left unchanged. |
|
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7885 The definition of what a lowercase letter is depends on the current locale. |
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|
7886 |
|
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|
7887 |
|
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|
7888 |
|
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|
7889 |
|
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|
7890 |
|
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|
7891 <h3>6.4.1 – <a name="6.4.1">Patterns</a></h3> |
|
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7892 |
|
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|
7893 <p> |
|
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7894 Patterns in Lua are described by regular strings, |
|
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|
7895 which are interpreted as patterns by the pattern-matching functions |
|
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7896 <a href="#pdf-string.find"><code>string.find</code></a>, |
|
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7897 <a href="#pdf-string.gmatch"><code>string.gmatch</code></a>, |
|
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7898 <a href="#pdf-string.gsub"><code>string.gsub</code></a>, |
|
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7899 and <a href="#pdf-string.match"><code>string.match</code></a>. |
|
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7900 This section describes the syntax and the meaning |
|
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7901 (that is, what they match) of these strings. |
|
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|
7902 |
|
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|
7903 |
|
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|
7904 |
|
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|
7905 <h4>Character Class:</h4><p> |
|
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|
7906 A <em>character class</em> is used to represent a set of characters. |
|
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|
7907 The following combinations are allowed in describing a character class: |
|
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|
7908 |
|
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|
7909 <ul> |
|
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|
7910 |
|
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|
7911 <li><b><em>x</em>: </b> |
|
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|
7912 (where <em>x</em> is not one of the <em>magic characters</em> |
|
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7913 <code>^$()%.[]*+-?</code>) |
|
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7914 represents the character <em>x</em> itself. |
|
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|
7915 </li> |
|
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|
7916 |
|
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|
7917 <li><b><code>.</code>: </b> (a dot) represents all characters.</li> |
|
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|
7918 |
|
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|
7919 <li><b><code>%a</code>: </b> represents all letters.</li> |
|
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|
7920 |
|
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|
7921 <li><b><code>%c</code>: </b> represents all control characters.</li> |
|
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7922 |
|
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|
7923 <li><b><code>%d</code>: </b> represents all digits.</li> |
|
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|
7924 |
|
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|
7925 <li><b><code>%g</code>: </b> represents all printable characters except space.</li> |
|
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|
7926 |
|
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|
7927 <li><b><code>%l</code>: </b> represents all lowercase letters.</li> |
|
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|
7928 |
|
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|
7929 <li><b><code>%p</code>: </b> represents all punctuation characters.</li> |
|
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|
7930 |
|
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|
7931 <li><b><code>%s</code>: </b> represents all space characters.</li> |
|
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|
7932 |
|
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|
7933 <li><b><code>%u</code>: </b> represents all uppercase letters.</li> |
|
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|
7934 |
|
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|
7935 <li><b><code>%w</code>: </b> represents all alphanumeric characters.</li> |
|
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|
7936 |
|
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|
7937 <li><b><code>%x</code>: </b> represents all hexadecimal digits.</li> |
|
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|
7938 |
|
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|
7939 <li><b><code>%<em>x</em></code>: </b> (where <em>x</em> is any non-alphanumeric character) |
|
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|
7940 represents the character <em>x</em>. |
|
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|
7941 This is the standard way to escape the magic characters. |
|
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|
7942 Any non-alphanumeric character |
|
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|
7943 (including all punctuations, even the non-magical) |
|
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|
7944 can be preceded by a '<code>%</code>' |
|
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|
7945 when used to represent itself in a pattern. |
|
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|
7946 </li> |
|
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|
7947 |
|
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|
7948 <li><b><code>[<em>set</em>]</code>: </b> |
|
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|
7949 represents the class which is the union of all |
|
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|
7950 characters in <em>set</em>. |
|
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|
7951 A range of characters can be specified by |
|
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|
7952 separating the end characters of the range, |
|
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|
7953 in ascending order, with a '<code>-</code>'. |
|
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|
7954 All classes <code>%</code><em>x</em> described above can also be used as |
|
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|
7955 components in <em>set</em>. |
|
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|
7956 All other characters in <em>set</em> represent themselves. |
|
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|
7957 For example, <code>[%w_]</code> (or <code>[_%w]</code>) |
|
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7958 represents all alphanumeric characters plus the underscore, |
|
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7959 <code>[0-7]</code> represents the octal digits, |
|
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|
7960 and <code>[0-7%l%-]</code> represents the octal digits plus |
|
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|
7961 the lowercase letters plus the '<code>-</code>' character. |
|
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|
7962 |
|
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|
7963 |
|
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|
7964 <p> |
|
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|
7965 The interaction between ranges and classes is not defined. |
|
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|
7966 Therefore, patterns like <code>[%a-z]</code> or <code>[a-%%]</code> |
|
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|
7967 have no meaning. |
|
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|
7968 </li> |
|
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|
7969 |
|
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|
7970 <li><b><code>[^<em>set</em>]</code>: </b> |
|
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7971 represents the complement of <em>set</em>, |
|
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|
7972 where <em>set</em> is interpreted as above. |
|
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|
7973 </li> |
|
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|
7974 |
|
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|
7975 </ul><p> |
|
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|
7976 For all classes represented by single letters (<code>%a</code>, <code>%c</code>, etc.), |
|
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7977 the corresponding uppercase letter represents the complement of the class. |
|
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|
7978 For instance, <code>%S</code> represents all non-space characters. |
|
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|
7979 |
|
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|
7980 |
|
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|
7981 <p> |
|
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changeset
|
7982 The definitions of letter, space, and other character groups |
|
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|
7983 depend on the current locale. |
|
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|
7984 In particular, the class <code>[a-z]</code> may not be equivalent to <code>%l</code>. |
|
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|
7985 |
|
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diff
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|
7986 |
|
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diff
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|
7987 |
|
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diff
changeset
|
7988 |
|
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|
7989 |
|
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|
7990 <h4>Pattern Item:</h4><p> |
|
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|
7991 A <em>pattern item</em> can be |
|
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|
7992 |
|
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diff
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|
7993 <ul> |
|
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|
7994 |
|
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|
7995 <li> |
|
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|
7996 a single character class, |
|
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|
7997 which matches any single character in the class; |
|
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|
7998 </li> |
|
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|
7999 |
|
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|
8000 <li> |
|
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|
8001 a single character class followed by '<code>*</code>', |
|
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8002 which matches zero or more repetitions of characters in the class. |
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8003 These repetition items will always match the longest possible sequence; |
|
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8004 </li> |
|
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|
8005 |
|
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|
8006 <li> |
|
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|
8007 a single character class followed by '<code>+</code>', |
|
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|
8008 which matches one or more repetitions of characters in the class. |
|
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|
8009 These repetition items will always match the longest possible sequence; |
|
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|
8010 </li> |
|
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|
8011 |
|
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|
8012 <li> |
|
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|
8013 a single character class followed by '<code>-</code>', |
|
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|
8014 which also matches zero or more repetitions of characters in the class. |
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|
8015 Unlike '<code>*</code>', |
|
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parents:
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|
8016 these repetition items will always match the shortest possible sequence; |
|
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parents:
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|
8017 </li> |
|
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parents:
diff
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|
8018 |
|
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|
8019 <li> |
|
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|
8020 a single character class followed by '<code>?</code>', |
|
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|
8021 which matches zero or one occurrence of a character in the class. |
|
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|
8022 It always matches one occurrence if possible; |
|
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|
8023 </li> |
|
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parents:
diff
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|
8024 |
|
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|
8025 <li> |
|
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|
8026 <code>%<em>n</em></code>, for <em>n</em> between 1 and 9; |
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|
8027 such item matches a substring equal to the <em>n</em>-th captured string |
|
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|
8028 (see below); |
|
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|
8029 </li> |
|
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parents:
diff
changeset
|
8030 |
|
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|
8031 <li> |
|
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|
8032 <code>%b<em>xy</em></code>, where <em>x</em> and <em>y</em> are two distinct characters; |
|
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|
8033 such item matches strings that start with <em>x</em>, end with <em>y</em>, |
|
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|
8034 and where the <em>x</em> and <em>y</em> are <em>balanced</em>. |
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|
8035 This means that, if one reads the string from left to right, |
|
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|
8036 counting <em>+1</em> for an <em>x</em> and <em>-1</em> for a <em>y</em>, |
|
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|
8037 the ending <em>y</em> is the first <em>y</em> where the count reaches 0. |
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|
8038 For instance, the item <code>%b()</code> matches expressions with |
|
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8039 balanced parentheses. |
|
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|
8040 </li> |
|
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|
8041 |
|
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|
8042 <li> |
|
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|
8043 <code>%f[<em>set</em>]</code>, a <em>frontier pattern</em>; |
|
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8044 such item matches an empty string at any position such that |
|
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8045 the next character belongs to <em>set</em> |
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8046 and the previous character does not belong to <em>set</em>. |
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|
8047 The set <em>set</em> is interpreted as previously described. |
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|
8048 The beginning and the end of the subject are handled as if |
|
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|
8049 they were the character '<code>\0</code>'. |
|
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|
8050 </li> |
|
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diff
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|
8051 |
|
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diff
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|
8052 </ul> |
|
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parents:
diff
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|
8053 |
|
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diff
changeset
|
8054 |
|
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parents:
diff
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|
8055 |
|
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diff
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|
8056 |
|
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|
8057 <h4>Pattern:</h4><p> |
|
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|
8058 A <em>pattern</em> is a sequence of pattern items. |
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|
8059 A caret '<code>^</code>' at the beginning of a pattern anchors the match at the |
|
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8060 beginning of the subject string. |
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|
8061 A '<code>$</code>' at the end of a pattern anchors the match at the |
|
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8062 end of the subject string. |
|
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|
8063 At other positions, |
|
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|
8064 '<code>^</code>' and '<code>$</code>' have no special meaning and represent themselves. |
|
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|
8065 |
|
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parents:
diff
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|
8066 |
|
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parents:
diff
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|
8067 |
|
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parents:
diff
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|
8068 |
|
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parents:
diff
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|
8069 |
|
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|
8070 <h4>Captures:</h4><p> |
|
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|
8071 A pattern can contain sub-patterns enclosed in parentheses; |
|
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|
8072 they describe <em>captures</em>. |
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8073 When a match succeeds, the substrings of the subject string |
|
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|
8074 that match captures are stored (<em>captured</em>) for future use. |
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|
8075 Captures are numbered according to their left parentheses. |
|
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|
8076 For instance, in the pattern <code>"(a*(.)%w(%s*))"</code>, |
|
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|
8077 the part of the string matching <code>"a*(.)%w(%s*)"</code> is |
|
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|
8078 stored as the first capture (and therefore has number 1); |
|
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|
8079 the character matching "<code>.</code>" is captured with number 2, |
|
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|
8080 and the part matching "<code>%s*</code>" has number 3. |
|
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|
8081 |
|
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parents:
diff
changeset
|
8082 |
|
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|
8083 <p> |
|
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|
8084 As a special case, the empty capture <code>()</code> captures |
|
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|
8085 the current string position (a number). |
|
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|
8086 For instance, if we apply the pattern <code>"()aa()"</code> on the |
|
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changeset
|
8087 string <code>"flaaap"</code>, there will be two captures: 3 and 5. |
|
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|
8088 |
|
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parents:
diff
changeset
|
8089 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8090 |
|
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parents:
diff
changeset
|
8091 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8092 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8093 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8094 |
|
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|
8095 <h3>6.4.2 – <a name="6.4.2">Format Strings for Pack and Unpack</a></h3> |
|
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diff
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|
8096 |
|
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parents:
diff
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|
8097 <p> |
|
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|
8098 The first argument to <a href="#pdf-string.pack"><code>string.pack</code></a>, |
|
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changeset
|
8099 <a href="#pdf-string.packsize"><code>string.packsize</code></a>, and <a href="#pdf-string.unpack"><code>string.unpack</code></a> |
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8100 is a format string, |
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8101 which describes the layout of the structure being created or read. |
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8102 |
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8103 |
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8104 <p> |
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8105 A format string is a sequence of conversion options. |
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8106 The conversion options are as follows: |
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8107 |
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8108 <ul> |
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8109 <li><b><code><</code>: </b>sets little endian</li> |
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8110 <li><b><code>></code>: </b>sets big endian</li> |
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8111 <li><b><code>=</code>: </b>sets native endian</li> |
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8112 <li><b><code>![<em>n</em>]</code>: </b>sets maximum alignment to <code>n</code> |
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8113 (default is native alignment)</li> |
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8114 <li><b><code>b</code>: </b>a signed byte (<code>char</code>)</li> |
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8115 <li><b><code>B</code>: </b>an unsigned byte (<code>char</code>)</li> |
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8116 <li><b><code>h</code>: </b>a signed <code>short</code> (native size)</li> |
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8117 <li><b><code>H</code>: </b>an unsigned <code>short</code> (native size)</li> |
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8118 <li><b><code>l</code>: </b>a signed <code>long</code> (native size)</li> |
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8119 <li><b><code>L</code>: </b>an unsigned <code>long</code> (native size)</li> |
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8120 <li><b><code>j</code>: </b>a <code>lua_Integer</code></li> |
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8121 <li><b><code>J</code>: </b>a <code>lua_Unsigned</code></li> |
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8122 <li><b><code>T</code>: </b>a <code>size_t</code> (native size)</li> |
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8123 <li><b><code>i[<em>n</em>]</code>: </b>a signed <code>int</code> with <code>n</code> bytes |
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8124 (default is native size)</li> |
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8125 <li><b><code>I[<em>n</em>]</code>: </b>an unsigned <code>int</code> with <code>n</code> bytes |
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8126 (default is native size)</li> |
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8127 <li><b><code>f</code>: </b>a <code>float</code> (native size)</li> |
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8128 <li><b><code>d</code>: </b>a <code>double</code> (native size)</li> |
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8129 <li><b><code>n</code>: </b>a <code>lua_Number</code></li> |
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8130 <li><b><code>c<em>n</em></code>: </b>a fixed-sized string with <code>n</code> bytes</li> |
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8131 <li><b><code>z</code>: </b>a zero-terminated string</li> |
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8132 <li><b><code>s[<em>n</em>]</code>: </b>a string preceded by its length |
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8133 coded as an unsigned integer with <code>n</code> bytes |
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8134 (default is a <code>size_t</code>)</li> |
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8135 <li><b><code>x</code>: </b>one byte of padding</li> |
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8136 <li><b><code>X<em>op</em></code>: </b>an empty item that aligns |
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8137 according to option <code>op</code> |
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8138 (which is otherwise ignored)</li> |
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8139 <li><b>'<code> </code>': </b>(empty space) ignored</li> |
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8140 </ul><p> |
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8141 (A "<code>[<em>n</em>]</code>" means an optional integral numeral.) |
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8142 Except for padding, spaces, and configurations |
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8143 (options "<code>xX <=>!</code>"), |
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8144 each option corresponds to an argument (in <a href="#pdf-string.pack"><code>string.pack</code></a>) |
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8145 or a result (in <a href="#pdf-string.unpack"><code>string.unpack</code></a>). |
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8146 |
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8147 |
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8148 <p> |
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8149 For options "<code>!<em>n</em></code>", "<code>s<em>n</em></code>", "<code>i<em>n</em></code>", and "<code>I<em>n</em></code>", |
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8150 <code>n</code> can be any integer between 1 and 16. |
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8151 All integral options check overflows; |
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8152 <a href="#pdf-string.pack"><code>string.pack</code></a> checks whether the given value fits in the given size; |
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8153 <a href="#pdf-string.unpack"><code>string.unpack</code></a> checks whether the read value fits in a Lua integer. |
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8154 |
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8155 |
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8156 <p> |
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8157 Any format string starts as if prefixed by "<code>!1=</code>", |
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8158 that is, |
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8159 with maximum alignment of 1 (no alignment) |
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8160 and native endianness. |
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8161 |
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8162 |
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8163 <p> |
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8164 Alignment works as follows: |
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8165 For each option, |
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8166 the format gets extra padding until the data starts |
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8167 at an offset that is a multiple of the minimum between the |
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8168 option size and the maximum alignment; |
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8169 this minimum must be a power of 2. |
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8170 Options "<code>c</code>" and "<code>z</code>" are not aligned; |
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8171 option "<code>s</code>" follows the alignment of its starting integer. |
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8172 |
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8173 |
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8174 <p> |
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8175 All padding is filled with zeros by <a href="#pdf-string.pack"><code>string.pack</code></a> |
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8176 (and ignored by <a href="#pdf-string.unpack"><code>string.unpack</code></a>). |
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8177 |
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8178 |
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8179 |
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8180 |
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8181 |
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8182 |
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8183 |
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8184 <h2>6.5 – <a name="6.5">UTF-8 Support</a></h2> |
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8185 |
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8186 <p> |
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8187 This library provides basic support for UTF-8 encoding. |
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8188 It provides all its functions inside the table <a name="pdf-utf8"><code>utf8</code></a>. |
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8189 This library does not provide any support for Unicode other |
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8190 than the handling of the encoding. |
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8191 Any operation that needs the meaning of a character, |
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8192 such as character classification, is outside its scope. |
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8193 |
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8194 |
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8195 <p> |
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8196 Unless stated otherwise, |
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8197 all functions that expect a byte position as a parameter |
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8198 assume that the given position is either the start of a byte sequence |
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8199 or one plus the length of the subject string. |
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8200 As in the string library, |
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8201 negative indices count from the end of the string. |
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8202 |
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8203 |
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8204 <p> |
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8205 <hr><h3><a name="pdf-utf8.char"><code>utf8.char (···)</code></a></h3> |
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8206 Receives zero or more integers, |
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8207 converts each one to its corresponding UTF-8 byte sequence |
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8208 and returns a string with the concatenation of all these sequences. |
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8209 |
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|
8210 |
|
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diff
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|
8211 |
|
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diff
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|
8212 |
|
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diff
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|
8213 <p> |
|
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|
8214 <hr><h3><a name="pdf-utf8.charpattern"><code>utf8.charpattern</code></a></h3> |
|
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|
8215 The pattern (a string, not a function) "<code>[\0-\x7F\xC2-\xF4][\x80-\xBF]*</code>" |
|
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|
8216 (see <a href="#6.4.1">§6.4.1</a>), |
|
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|
8217 which matches exactly one UTF-8 byte sequence, |
|
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|
8218 assuming that the subject is a valid UTF-8 string. |
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|
8219 |
|
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diff
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|
8220 |
|
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diff
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|
8221 |
|
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diff
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|
8222 |
|
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|
8223 <p> |
|
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|
8224 <hr><h3><a name="pdf-utf8.codes"><code>utf8.codes (s)</code></a></h3> |
|
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|
8225 |
|
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diff
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|
8226 |
|
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|
8227 <p> |
|
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|
8228 Returns values so that the construction |
|
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|
8229 |
|
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|
8230 <pre> |
|
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|
8231 for p, c in utf8.codes(s) do <em>body</em> end |
|
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|
8232 </pre><p> |
|
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8233 will iterate over all characters in string <code>s</code>, |
|
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|
8234 with <code>p</code> being the position (in bytes) and <code>c</code> the code point |
|
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|
8235 of each character. |
|
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|
8236 It raises an error if it meets any invalid byte sequence. |
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|
8237 |
|
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|
8238 |
|
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diff
changeset
|
8239 |
|
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diff
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|
8240 |
|
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|
8241 <p> |
|
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|
8242 <hr><h3><a name="pdf-utf8.codepoint"><code>utf8.codepoint (s [, i [, j]])</code></a></h3> |
|
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|
8243 Returns the codepoints (as integers) from all characters in <code>s</code> |
|
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|
8244 that start between byte position <code>i</code> and <code>j</code> (both included). |
|
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|
8245 The default for <code>i</code> is 1 and for <code>j</code> is <code>i</code>. |
|
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|
8246 It raises an error if it meets any invalid byte sequence. |
|
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|
8247 |
|
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diff
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|
8248 |
|
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diff
changeset
|
8249 |
|
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diff
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|
8250 |
|
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|
8251 <p> |
|
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|
8252 <hr><h3><a name="pdf-utf8.len"><code>utf8.len (s [, i [, j]])</code></a></h3> |
|
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|
8253 Returns the number of UTF-8 characters in string <code>s</code> |
|
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|
8254 that start between positions <code>i</code> and <code>j</code> (both inclusive). |
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|
8255 The default for <code>i</code> is 1 and for <code>j</code> is -1. |
|
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|
8256 If it finds any invalid byte sequence, |
|
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|
8257 returns a false value plus the position of the first invalid byte. |
|
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|
8258 |
|
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diff
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|
8259 |
|
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diff
changeset
|
8260 |
|
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parents:
diff
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|
8261 |
|
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|
8262 <p> |
|
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|
8263 <hr><h3><a name="pdf-utf8.offset"><code>utf8.offset (s, n [, i])</code></a></h3> |
|
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|
8264 Returns the position (in bytes) where the encoding of the |
|
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|
8265 <code>n</code>-th character of <code>s</code> |
|
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|
8266 (counting from position <code>i</code>) starts. |
|
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|
8267 A negative <code>n</code> gets characters before position <code>i</code>. |
|
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|
8268 The default for <code>i</code> is 1 when <code>n</code> is non-negative |
|
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|
8269 and <code>#s + 1</code> otherwise, |
|
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|
8270 so that <code>utf8.offset(s, -n)</code> gets the offset of the |
|
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|
8271 <code>n</code>-th character from the end of the string. |
|
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|
8272 If the specified character is neither in the subject |
|
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|
8273 nor right after its end, |
|
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|
8274 the function returns <b>nil</b>. |
|
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|
8275 |
|
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|
8276 |
|
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|
8277 <p> |
|
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|
8278 As a special case, |
|
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|
8279 when <code>n</code> is 0 the function returns the start of the encoding |
|
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|
8280 of the character that contains the <code>i</code>-th byte of <code>s</code>. |
|
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|
8281 |
|
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diff
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|
8282 |
|
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|
8283 <p> |
|
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|
8284 This function assumes that <code>s</code> is a valid UTF-8 string. |
|
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|
8285 |
|
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diff
changeset
|
8286 |
|
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parents:
diff
changeset
|
8287 |
|
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parents:
diff
changeset
|
8288 |
|
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parents:
diff
changeset
|
8289 |
|
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diff
changeset
|
8290 |
|
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|
8291 |
|
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|
8292 <h2>6.6 – <a name="6.6">Table Manipulation</a></h2> |
|
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|
8293 |
|
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|
8294 <p> |
|
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|
8295 This library provides generic functions for table manipulation. |
|
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|
8296 It provides all its functions inside the table <a name="pdf-table"><code>table</code></a>. |
|
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|
8297 |
|
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|
8298 |
|
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|
8299 <p> |
|
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changeset
|
8300 Remember that, whenever an operation needs the length of a table, |
|
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|
8301 the table must be a proper sequence |
|
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|
8302 or have a <code>__len</code> metamethod (see <a href="#3.4.7">§3.4.7</a>). |
|
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|
8303 All functions ignore non-numeric keys |
|
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|
8304 in the tables given as arguments. |
|
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|
8305 |
|
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changeset
|
8306 |
|
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|
8307 <p> |
|
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|
8308 <hr><h3><a name="pdf-table.concat"><code>table.concat (list [, sep [, i [, j]]])</code></a></h3> |
|
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changeset
|
8309 |
|
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changeset
|
8310 |
|
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changeset
|
8311 <p> |
|
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changeset
|
8312 Given a list where all elements are strings or numbers, |
|
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|
8313 returns the string <code>list[i]..sep..list[i+1] ··· sep..list[j]</code>. |
|
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|
8314 The default value for <code>sep</code> is the empty string, |
|
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|
8315 the default for <code>i</code> is 1, |
|
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|
8316 and the default for <code>j</code> is <code>#list</code>. |
|
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|
8317 If <code>i</code> is greater than <code>j</code>, returns the empty string. |
|
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changeset
|
8318 |
|
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changeset
|
8319 |
|
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parents:
diff
changeset
|
8320 |
|
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changeset
|
8321 |
|
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changeset
|
8322 <p> |
|
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changeset
|
8323 <hr><h3><a name="pdf-table.insert"><code>table.insert (list, [pos,] value)</code></a></h3> |
|
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changeset
|
8324 |
|
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changeset
|
8325 |
|
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diff
changeset
|
8326 <p> |
|
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diff
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|
8327 Inserts element <code>value</code> at position <code>pos</code> in <code>list</code>, |
|
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|
8328 shifting up the elements |
|
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|
8329 <code>list[pos], list[pos+1], ···, list[#list]</code>. |
|
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|
8330 The default value for <code>pos</code> is <code>#list+1</code>, |
|
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|
8331 so that a call <code>table.insert(t,x)</code> inserts <code>x</code> at the end |
|
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|
8332 of list <code>t</code>. |
|
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|
8333 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8334 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8335 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
8336 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
8337 <p> |
|
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|
8338 <hr><h3><a name="pdf-table.move"><code>table.move (a1, f, e, t [,a2])</code></a></h3> |
|
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|
8339 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
8340 |
|
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diff
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|
8341 <p> |
|
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|
8342 Moves elements from table <code>a1</code> to table <code>a2</code>. |
|
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|
8343 This function performs the equivalent to the following |
|
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|
8344 multiple assignment: |
|
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|
8345 <code>a2[t],··· = a1[f],···,a1[e]</code>. |
|
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|
8346 The default for <code>a2</code> is <code>a1</code>. |
|
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|
8347 The destination range can overlap with the source range. |
|
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|
8348 Index <code>f</code> must be positive. |
|
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|
8349 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8350 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8351 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8352 |
|
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|
8353 <p> |
|
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|
8354 <hr><h3><a name="pdf-table.pack"><code>table.pack (···)</code></a></h3> |
|
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|
8355 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
8356 |
|
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|
8357 <p> |
|
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|
8358 Returns a new table with all parameters stored into keys 1, 2, etc. |
|
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|
8359 and with a field "<code>n</code>" with the total number of parameters. |
|
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|
8360 Note that the resulting table may not be a sequence. |
|
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|
8361 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8362 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8363 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8364 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
8365 <p> |
|
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|
8366 <hr><h3><a name="pdf-table.remove"><code>table.remove (list [, pos])</code></a></h3> |
|
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|
8367 |
|
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changeset
|
8368 |
|
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|
8369 <p> |
|
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|
8370 Removes from <code>list</code> the element at position <code>pos</code>, |
|
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|
8371 returning the value of the removed element. |
|
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|
8372 When <code>pos</code> is an integer between 1 and <code>#list</code>, |
|
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|
8373 it shifts down the elements |
|
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diff
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|
8374 <code>list[pos+1], list[pos+2], ···, list[#list]</code> |
|
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|
8375 and erases element <code>list[#list]</code>; |
|
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|
8376 The index <code>pos</code> can also be 0 when <code>#list</code> is 0, |
|
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|
8377 or <code>#list + 1</code>; |
|
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|
8378 in those cases, the function erases the element <code>list[pos]</code>. |
|
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changeset
|
8379 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8380 |
|
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diff
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|
8381 <p> |
|
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diff
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|
8382 The default value for <code>pos</code> is <code>#list</code>, |
|
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|
8383 so that a call <code>table.remove(l)</code> removes the last element |
|
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diff
changeset
|
8384 of list <code>l</code>. |
|
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changeset
|
8385 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8386 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8387 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8388 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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|
8389 <p> |
|
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|
8390 <hr><h3><a name="pdf-table.sort"><code>table.sort (list [, comp])</code></a></h3> |
|
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changeset
|
8391 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8392 |
|
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diff
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|
8393 <p> |
|
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diff
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|
8394 Sorts list elements in a given order, <em>in-place</em>, |
|
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|
8395 from <code>list[1]</code> to <code>list[#list]</code>. |
|
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|
8396 If <code>comp</code> is given, |
|
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diff
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|
8397 then it must be a function that receives two list elements |
|
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|
8398 and returns true when the first element must come |
|
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parents:
diff
changeset
|
8399 before the second in the final order |
|
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diff
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|
8400 (so that <code>not comp(list[i+1],list[i])</code> will be true after the sort). |
|
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changeset
|
8401 If <code>comp</code> is not given, |
|
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diff
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|
8402 then the standard Lua operator <code><</code> is used instead. |
|
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changeset
|
8403 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8404 |
|
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diff
changeset
|
8405 <p> |
|
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changeset
|
8406 The sort algorithm is not stable; |
|
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diff
changeset
|
8407 that is, elements considered equal by the given order |
|
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diff
changeset
|
8408 may have their relative positions changed by the sort. |
|
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diff
changeset
|
8409 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8410 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8411 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8412 |
|
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diff
changeset
|
8413 <p> |
|
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changeset
|
8414 <hr><h3><a name="pdf-table.unpack"><code>table.unpack (list [, i [, j]])</code></a></h3> |
|
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changeset
|
8415 |
|
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parents:
diff
changeset
|
8416 |
|
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changeset
|
8417 <p> |
|
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changeset
|
8418 Returns the elements from the given list. |
|
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diff
changeset
|
8419 This function is equivalent to |
|
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diff
changeset
|
8420 |
|
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diff
changeset
|
8421 <pre> |
|
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diff
changeset
|
8422 return list[i], list[i+1], ···, list[j] |
|
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changeset
|
8423 </pre><p> |
|
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changeset
|
8424 By default, <code>i</code> is 1 and <code>j</code> is <code>#list</code>. |
|
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changeset
|
8425 |
|
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parents:
diff
changeset
|
8426 |
|
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parents:
diff
changeset
|
8427 |
|
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parents:
diff
changeset
|
8428 |
|
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parents:
diff
changeset
|
8429 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8430 |
|
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diff
changeset
|
8431 |
|
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|
8432 <h2>6.7 – <a name="6.7">Mathematical Functions</a></h2> |
|
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changeset
|
8433 |
|
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diff
changeset
|
8434 <p> |
|
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changeset
|
8435 This library provides basic mathematical functions. |
|
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|
8436 It provides all its functions and constants inside the table <a name="pdf-math"><code>math</code></a>. |
|
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|
8437 Functions with the annotation "<code>integer/float</code>" give |
|
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|
8438 integer results for integer arguments |
|
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changeset
|
8439 and float results for float (or mixed) arguments. |
|
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diff
changeset
|
8440 Rounding functions |
|
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changeset
|
8441 (<a href="#pdf-math.ceil"><code>math.ceil</code></a>, <a href="#pdf-math.floor"><code>math.floor</code></a>, and <a href="#pdf-math.modf"><code>math.modf</code></a>) |
|
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parents:
diff
changeset
|
8442 return an integer when the result fits in the range of an integer, |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8443 or a float otherwise. |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8444 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8445 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8446 <p> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8447 <hr><h3><a name="pdf-math.abs"><code>math.abs (x)</code></a></h3> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8448 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8449 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8450 <p> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8451 Returns the absolute value of <code>x</code>. (integer/float) |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8452 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8453 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8454 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8455 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8456 <p> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8457 <hr><h3><a name="pdf-math.acos"><code>math.acos (x)</code></a></h3> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8458 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8459 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8460 <p> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8461 Returns the arc cosine of <code>x</code> (in radians). |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8462 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8463 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8464 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8465 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8466 <p> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8467 <hr><h3><a name="pdf-math.asin"><code>math.asin (x)</code></a></h3> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8468 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8469 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8470 <p> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8471 Returns the arc sine of <code>x</code> (in radians). |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8472 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8473 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8474 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8475 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8476 <p> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8477 <hr><h3><a name="pdf-math.atan"><code>math.atan (y [, x])</code></a></h3> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8478 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8479 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8480 <p> |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8481 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8482 Returns the arc tangent of <code>y/x</code> (in radians), |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8483 but uses the signs of both parameters to find the |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8484 quadrant of the result. |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8485 (It also handles correctly the case of <code>x</code> being zero.) |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8486 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8487 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8488 <p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8489 The default value for <code>x</code> is 1, |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8490 so that the call <code>math.atan(y)</code> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8491 returns the arc tangent of <code>y</code>. |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8492 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8493 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8494 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8495 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8496 <p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8497 <hr><h3><a name="pdf-math.ceil"><code>math.ceil (x)</code></a></h3> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8498 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8499 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8500 <p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8501 Returns the smallest integral value larger than or equal to <code>x</code>. |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8502 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8503 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8504 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8505 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8506 <p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8507 <hr><h3><a name="pdf-math.cos"><code>math.cos (x)</code></a></h3> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8508 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8509 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8510 <p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8511 Returns the cosine of <code>x</code> (assumed to be in radians). |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8512 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8513 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8514 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8515 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8516 <p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8517 <hr><h3><a name="pdf-math.deg"><code>math.deg (x)</code></a></h3> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8518 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8519 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8520 <p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8521 Converts the angle <code>x</code> from radians to degrees. |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8522 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8523 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8524 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8525 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8526 <p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8527 <hr><h3><a name="pdf-math.exp"><code>math.exp (x)</code></a></h3> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8528 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8529 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8530 <p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8531 Returns the value <em>e<sup>x</sup></em> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8532 (where <code>e</code> is the base of natural logarithms). |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8533 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8534 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8535 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8536 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8537 <p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8538 <hr><h3><a name="pdf-math.floor"><code>math.floor (x)</code></a></h3> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8539 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8540 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8541 <p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8542 Returns the largest integral value smaller than or equal to <code>x</code>. |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8543 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8544 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8545 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8546 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8547 <p> |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8548 <hr><h3><a name="pdf-math.fmod"><code>math.fmod (x, y)</code></a></h3> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8549 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8550 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8551 <p> |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8552 Returns the remainder of the division of <code>x</code> by <code>y</code> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8553 that rounds the quotient towards zero. (integer/float) |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8554 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8555 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8556 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8557 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8558 <p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8559 <hr><h3><a name="pdf-math.huge"><code>math.huge</code></a></h3> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8560 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8561 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8562 <p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8563 The float value <code>HUGE_VAL</code>, |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8564 a value larger than any other numerical value. |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8565 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8566 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8567 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8568 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8569 <p> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
8570 <hr><h3><a name="pdf-math.log"><code>math.log (x [, base])</code></a></h3> |
|
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parents:
diff
changeset
|
8571 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8572 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8573 <p> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8574 Returns the logarithm of <code>x</code> in the given base. |
|
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parents:
diff
changeset
|
8575 The default for <code>base</code> is <em>e</em> |
|
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parents:
diff
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|
8576 (so that the function returns the natural logarithm of <code>x</code>). |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
8577 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8578 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8579 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8580 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8581 <p> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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|
8582 <hr><h3><a name="pdf-math.max"><code>math.max (x, ···)</code></a></h3> |
|
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parents:
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|
8583 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8584 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
8585 <p> |
|
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parents:
diff
changeset
|
8586 Returns the argument with the maximum value, |
|
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parents:
diff
changeset
|
8587 according to the Lua operator <code><</code>. (integer/float) |
|
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parents:
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|
8588 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8589 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8590 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8591 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
8592 <p> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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|
8593 <hr><h3><a name="pdf-math.maxinteger"><code>math.maxinteger</code></a></h3> |
|
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parents:
diff
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|
8594 An integer with the maximum value for an integer. |
|
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parents:
diff
changeset
|
8595 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8596 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8597 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8598 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
8599 <p> |
|
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Franklin Schmidt <fschmidt@gmail.com>
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|
8600 <hr><h3><a name="pdf-math.min"><code>math.min (x, ···)</code></a></h3> |
|
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parents:
diff
changeset
|
8601 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8602 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8603 <p> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8604 Returns the argument with the minimum value, |
|
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parents:
diff
changeset
|
8605 according to the Lua operator <code><</code>. (integer/float) |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8606 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8607 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8608 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8609 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8610 <p> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
8611 <hr><h3><a name="pdf-math.mininteger"><code>math.mininteger</code></a></h3> |
|
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parents:
diff
changeset
|
8612 An integer with the minimum value for an integer. |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8613 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8614 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8615 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8616 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8617 <p> |
|
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parents:
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|
8618 <hr><h3><a name="pdf-math.modf"><code>math.modf (x)</code></a></h3> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8619 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8620 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8621 <p> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8622 Returns the integral part of <code>x</code> and the fractional part of <code>x</code>. |
|
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parents:
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changeset
|
8623 Its second result is always a float. |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8624 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8625 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8626 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8627 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8628 <p> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8629 <hr><h3><a name="pdf-math.pi"><code>math.pi</code></a></h3> |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8630 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8631 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8632 <p> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8633 The value of <em>π</em>. |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8634 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8635 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8636 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8637 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8638 <p> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8639 <hr><h3><a name="pdf-math.rad"><code>math.rad (x)</code></a></h3> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8640 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8641 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8642 <p> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8643 Converts the angle <code>x</code> from degrees to radians. |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8644 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8645 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8646 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8647 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8648 <p> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8649 <hr><h3><a name="pdf-math.random"><code>math.random ([m [, n]])</code></a></h3> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8650 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8651 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8652 <p> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8653 When called without arguments, |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8654 returns a pseudo-random float with uniform distribution |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8655 in the range <em>[0,1)</em>. |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8656 When called with two integers <code>m</code> and <code>n</code>, |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8657 <code>math.random</code> returns a pseudo-random integer |
|
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parents:
diff
changeset
|
8658 with uniform distribution in the range <em>[m, n]</em>. |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8659 (The value <em>m-n</em> cannot be negative and must fit in a Lua integer.) |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8660 The call <code>math.random(n)</code> is equivalent to <code>math.random(1,n)</code>. |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8661 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8662 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8663 <p> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8664 This function is an interface to the underling |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8665 pseudo-random generator function provided by C. |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8666 No guarantees can be given for its statistical properties. |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8667 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8668 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8669 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8670 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8671 <p> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8672 <hr><h3><a name="pdf-math.randomseed"><code>math.randomseed (x)</code></a></h3> |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8673 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8674 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8675 <p> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8676 Sets <code>x</code> as the "seed" |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8677 for the pseudo-random generator: |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8678 equal seeds produce equal sequences of numbers. |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8679 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8680 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8681 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8682 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8683 <p> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8684 <hr><h3><a name="pdf-math.sin"><code>math.sin (x)</code></a></h3> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8685 |
|
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parents:
diff
changeset
|
8686 |
|
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parents:
diff
changeset
|
8687 <p> |
|
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parents:
diff
changeset
|
8688 Returns the sine of <code>x</code> (assumed to be in radians). |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
8689 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8690 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8691 |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8692 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8693 <p> |
|
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parents:
diff
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|
8694 <hr><h3><a name="pdf-math.sqrt"><code>math.sqrt (x)</code></a></h3> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
8695 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8696 |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
8697 <p> |
|
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parents:
diff
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|
8698 Returns the square root of <code>x</code>. |
|
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parents:
diff
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|
8699 (You can also use the expression <code>x^0.5</code> to compute this value.) |
|
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changeset
|
8700 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8701 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8702 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8703 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
8704 <p> |
|
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parents:
diff
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|
8705 <hr><h3><a name="pdf-math.tan"><code>math.tan (x)</code></a></h3> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
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|
8706 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8707 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
8708 <p> |
|
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parents:
diff
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|
8709 Returns the tangent of <code>x</code> (assumed to be in radians). |
|
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parents:
diff
changeset
|
8710 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8711 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8712 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8713 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
8714 <p> |
|
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parents:
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|
8715 <hr><h3><a name="pdf-math.tointeger"><code>math.tointeger (x)</code></a></h3> |
|
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parents:
diff
changeset
|
8716 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8717 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8718 <p> |
|
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parents:
diff
changeset
|
8719 If the value <code>x</code> is convertible to an integer, |
|
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parents:
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changeset
|
8720 returns that integer. |
|
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parents:
diff
changeset
|
8721 Otherwise, returns <b>nil</b>. |
|
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parents:
diff
changeset
|
8722 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8723 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8724 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8725 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8726 <p> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8727 <hr><h3><a name="pdf-math.type"><code>math.type (x)</code></a></h3> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8728 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8729 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8730 <p> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8731 Returns "<code>integer</code>" if <code>x</code> is an integer, |
|
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parents:
diff
changeset
|
8732 "<code>float</code>" if it is a float, |
|
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parents:
diff
changeset
|
8733 or <b>nil</b> if <code>x</code> is not a number. |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8734 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8735 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8736 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8737 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8738 <p> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8739 <hr><h3><a name="pdf-math.ult"><code>math.ult (m, n)</code></a></h3> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8740 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8741 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8742 <p> |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8743 Returns a boolean, |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
8744 true if integer <code>m</code> is below integer <code>n</code> when |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8745 they are compared as unsigned integers. |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8746 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8747 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8748 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8749 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8750 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8751 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8752 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8753 <h2>6.8 – <a name="6.8">Input and Output Facilities</a></h2> |
|
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parents:
diff
changeset
|
8754 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8755 <p> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8756 The I/O library provides two different styles for file manipulation. |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8757 The first one uses implicit file handles; |
|
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parents:
diff
changeset
|
8758 that is, there are operations to set a default input file and a |
|
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parents:
diff
changeset
|
8759 default output file, |
|
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parents:
diff
changeset
|
8760 and all input/output operations are over these default files. |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8761 The second style uses explicit file handles. |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8762 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8763 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8764 <p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8765 When using implicit file handles, |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
8766 all operations are supplied by table <a name="pdf-io"><code>io</code></a>. |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8767 When using explicit file handles, |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8768 the operation <a href="#pdf-io.open"><code>io.open</code></a> returns a file handle |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8769 and then all operations are supplied as methods of the file handle. |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8770 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8771 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8772 <p> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8773 The table <code>io</code> also provides |
|
e01cddba3433
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parents:
diff
changeset
|
8774 three predefined file handles with their usual meanings from C: |
|
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parents:
diff
changeset
|
8775 <a name="pdf-io.stdin"><code>io.stdin</code></a>, <a name="pdf-io.stdout"><code>io.stdout</code></a>, and <a name="pdf-io.stderr"><code>io.stderr</code></a>. |
|
e01cddba3433
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parents:
diff
changeset
|
8776 The I/O library never closes these files. |
|
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parents:
diff
changeset
|
8777 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8778 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8779 <p> |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8780 Unless otherwise stated, |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8781 all I/O functions return <b>nil</b> on failure |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8782 (plus an error message as a second result and |
|
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parents:
diff
changeset
|
8783 a system-dependent error code as a third result) |
|
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parents:
diff
changeset
|
8784 and some value different from <b>nil</b> on success. |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8785 On non-POSIX systems, |
|
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parents:
diff
changeset
|
8786 the computation of the error message and error code |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8787 in case of errors |
|
e01cddba3433
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parents:
diff
changeset
|
8788 may be not thread safe, |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8789 because they rely on the global C variable <code>errno</code>. |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8790 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8791 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8792 <p> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8793 <hr><h3><a name="pdf-io.close"><code>io.close ([file])</code></a></h3> |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8794 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8795 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8796 <p> |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8797 Equivalent to <code>file:close()</code>. |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8798 Without a <code>file</code>, closes the default output file. |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8799 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8800 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8801 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8802 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8803 <p> |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8804 <hr><h3><a name="pdf-io.flush"><code>io.flush ()</code></a></h3> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8805 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8806 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8807 <p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8808 Equivalent to <code>io.output():flush()</code>. |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8809 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8810 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8811 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8812 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8813 <p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8814 <hr><h3><a name="pdf-io.input"><code>io.input ([file])</code></a></h3> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8815 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8816 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8817 <p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8818 When called with a file name, it opens the named file (in text mode), |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8819 and sets its handle as the default input file. |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8820 When called with a file handle, |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8821 it simply sets this file handle as the default input file. |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8822 When called without parameters, |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8823 it returns the current default input file. |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8824 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8825 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8826 <p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8827 In case of errors this function raises the error, |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8828 instead of returning an error code. |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8829 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8830 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8831 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8832 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8833 <p> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8834 <hr><h3><a name="pdf-io.lines"><code>io.lines ([filename ···])</code></a></h3> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8835 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8836 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8837 <p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8838 Opens the given file name in read mode |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8839 and returns an iterator function that |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8840 works like <code>file:lines(···)</code> over the opened file. |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8841 When the iterator function detects the end of file, |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8842 it returns no values (to finish the loop) and automatically closes the file. |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8843 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8844 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8845 <p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8846 The call <code>io.lines()</code> (with no file name) is equivalent |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8847 to <code>io.input():lines("*l")</code>; |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8848 that is, it iterates over the lines of the default input file. |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8849 In this case it does not close the file when the loop ends. |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8850 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8851 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8852 <p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8853 In case of errors this function raises the error, |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8854 instead of returning an error code. |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8855 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8856 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8857 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8858 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8859 <p> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8860 <hr><h3><a name="pdf-io.open"><code>io.open (filename [, mode])</code></a></h3> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8861 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8862 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8863 <p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8864 This function opens a file, |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8865 in the mode specified in the string <code>mode</code>. |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8866 It returns a new file handle, |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8867 or, in case of errors, <b>nil</b> plus an error message. |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8868 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8869 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8870 <p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8871 The <code>mode</code> string can be any of the following: |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8872 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8873 <ul> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8874 <li><b>"<code>r</code>": </b> read mode (the default);</li> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8875 <li><b>"<code>w</code>": </b> write mode;</li> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8876 <li><b>"<code>a</code>": </b> append mode;</li> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8877 <li><b>"<code>r+</code>": </b> update mode, all previous data is preserved;</li> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8878 <li><b>"<code>w+</code>": </b> update mode, all previous data is erased;</li> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8879 <li><b>"<code>a+</code>": </b> append update mode, previous data is preserved, |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8880 writing is only allowed at the end of file.</li> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8881 </ul><p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8882 The <code>mode</code> string can also have a '<code>b</code>' at the end, |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8883 which is needed in some systems to open the file in binary mode. |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8884 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8885 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8886 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8887 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8888 <p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8889 <hr><h3><a name="pdf-io.output"><code>io.output ([file])</code></a></h3> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8890 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8891 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8892 <p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8893 Similar to <a href="#pdf-io.input"><code>io.input</code></a>, but operates over the default output file. |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8894 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8895 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8896 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8897 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8898 <p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8899 <hr><h3><a name="pdf-io.popen"><code>io.popen (prog [, mode])</code></a></h3> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8900 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8901 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8902 <p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8903 This function is system dependent and is not available |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8904 on all platforms. |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8905 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8906 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8907 <p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8908 Starts program <code>prog</code> in a separated process and returns |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8909 a file handle that you can use to read data from this program |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8910 (if <code>mode</code> is <code>"r"</code>, the default) |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8911 or to write data to this program |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8912 (if <code>mode</code> is <code>"w"</code>). |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8913 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8914 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8915 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8916 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8917 <p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8918 <hr><h3><a name="pdf-io.read"><code>io.read (···)</code></a></h3> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8919 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8920 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8921 <p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8922 Equivalent to <code>io.input():read(···)</code>. |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8923 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8924 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8925 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8926 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8927 <p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8928 <hr><h3><a name="pdf-io.tmpfile"><code>io.tmpfile ()</code></a></h3> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8929 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8930 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8931 <p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8932 Returns a handle for a temporary file. |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8933 This file is opened in update mode |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8934 and it is automatically removed when the program ends. |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8935 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8936 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8937 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8938 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8939 <p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8940 <hr><h3><a name="pdf-io.type"><code>io.type (obj)</code></a></h3> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8941 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8942 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8943 <p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8944 Checks whether <code>obj</code> is a valid file handle. |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8945 Returns the string <code>"file"</code> if <code>obj</code> is an open file handle, |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8946 <code>"closed file"</code> if <code>obj</code> is a closed file handle, |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8947 or <b>nil</b> if <code>obj</code> is not a file handle. |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8948 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8949 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8950 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8951 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8952 <p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8953 <hr><h3><a name="pdf-io.write"><code>io.write (···)</code></a></h3> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8954 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8955 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8956 <p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8957 Equivalent to <code>io.output():write(···)</code>. |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8958 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8959 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8960 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8961 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8962 <p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8963 <hr><h3><a name="pdf-file:close"><code>file:close ()</code></a></h3> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8964 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8965 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8966 <p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8967 Closes <code>file</code>. |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8968 Note that files are automatically closed when |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8969 their handles are garbage collected, |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8970 but that takes an unpredictable amount of time to happen. |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8971 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8972 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8973 <p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8974 When closing a file handle created with <a href="#pdf-io.popen"><code>io.popen</code></a>, |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8975 <a href="#pdf-file:close"><code>file:close</code></a> returns the same values |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8976 returned by <a href="#pdf-os.execute"><code>os.execute</code></a>. |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8977 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8978 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8979 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8980 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8981 <p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8982 <hr><h3><a name="pdf-file:flush"><code>file:flush ()</code></a></h3> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8983 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8984 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8985 <p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8986 Saves any written data to <code>file</code>. |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8987 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8988 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8989 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8990 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8991 <p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8992 <hr><h3><a name="pdf-file:lines"><code>file:lines (···)</code></a></h3> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8993 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8994 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8995 <p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8996 Returns an iterator function that, |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8997 each time it is called, |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8998 reads the file according to the given formats. |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8999 When no format is given, |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9000 uses "<code>l</code>" as a default. |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9001 As an example, the construction |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9002 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9003 <pre> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9004 for c in file:lines(1) do <em>body</em> end |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9005 </pre><p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9006 will iterate over all characters of the file, |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9007 starting at the current position. |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9008 Unlike <a href="#pdf-io.lines"><code>io.lines</code></a>, this function does not close the file |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9009 when the loop ends. |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9010 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9011 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9012 <p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9013 In case of errors this function raises the error, |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9014 instead of returning an error code. |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9015 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9016 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9017 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9018 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9019 <p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9020 <hr><h3><a name="pdf-file:read"><code>file:read (···)</code></a></h3> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9021 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9022 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9023 <p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9024 Reads the file <code>file</code>, |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9025 according to the given formats, which specify what to read. |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9026 For each format, |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9027 the function returns a string or a number with the characters read, |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9028 or <b>nil</b> if it cannot read data with the specified format. |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9029 (In this latter case, |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9030 the function does not read subsequent formats.) |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9031 When called without formats, |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9032 it uses a default format that reads the next line |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9033 (see below). |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9034 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9035 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9036 <p> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9037 The available formats are |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9038 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9039 <ul> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9040 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9041 <li><b>"<code>n</code>": </b> |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9042 reads a numeral and returns it as a float or an integer, |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9043 following the lexical conventions of Lua. |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9044 (The numeral may have leading spaces and a sign.) |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9045 This format always reads the longest input sequence that |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
9046 is a valid prefix for a number; |
|
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|
9047 if that prefix does not form a valid number |
|
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|
9048 (e.g., an empty string, "<code>0x</code>", or "<code>3.4e-</code>"), |
|
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|
9049 it is discarded and the function returns <b>nil</b>. |
|
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|
9050 </li> |
|
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diff
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|
9051 |
|
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|
9052 <li><b>"<code>i</code>": </b> |
|
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|
9053 reads an integral number and returns it as an integer. |
|
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|
9054 </li> |
|
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|
9055 |
|
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|
9056 <li><b>"<code>a</code>": </b> |
|
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|
9057 reads the whole file, starting at the current position. |
|
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|
9058 On end of file, it returns the empty string. |
|
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|
9059 </li> |
|
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|
9060 |
|
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|
9061 <li><b>"<code>l</code>": </b> |
|
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|
9062 reads the next line skipping the end of line, |
|
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|
9063 returning <b>nil</b> on end of file. |
|
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|
9064 This is the default format. |
|
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|
9065 </li> |
|
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|
9066 |
|
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|
9067 <li><b>"<code>L</code>": </b> |
|
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|
9068 reads the next line keeping the end-of-line character (if present), |
|
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diff
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|
9069 returning <b>nil</b> on end of file. |
|
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|
9070 </li> |
|
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diff
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|
9071 |
|
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|
9072 <li><b><em>number</em>: </b> |
|
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|
9073 reads a string with up to this number of bytes, |
|
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|
9074 returning <b>nil</b> on end of file. |
|
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|
9075 If <code>number</code> is zero, |
|
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|
9076 it reads nothing and returns an empty string, |
|
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|
9077 or <b>nil</b> on end of file. |
|
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|
9078 </li> |
|
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diff
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|
9079 |
|
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|
9080 </ul><p> |
|
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|
9081 The formats "<code>l</code>" and "<code>L</code>" should be used only for text files. |
|
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|
9082 |
|
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diff
changeset
|
9083 |
|
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diff
changeset
|
9084 |
|
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diff
changeset
|
9085 |
|
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|
9086 <p> |
|
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|
9087 <hr><h3><a name="pdf-file:seek"><code>file:seek ([whence [, offset]])</code></a></h3> |
|
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|
9088 |
|
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|
9089 |
|
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|
9090 <p> |
|
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|
9091 Sets and gets the file position, |
|
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|
9092 measured from the beginning of the file, |
|
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|
9093 to the position given by <code>offset</code> plus a base |
|
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|
9094 specified by the string <code>whence</code>, as follows: |
|
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|
9095 |
|
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|
9096 <ul> |
|
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|
9097 <li><b>"<code>set</code>": </b> base is position 0 (beginning of the file);</li> |
|
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|
9098 <li><b>"<code>cur</code>": </b> base is current position;</li> |
|
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|
9099 <li><b>"<code>end</code>": </b> base is end of file;</li> |
|
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|
9100 </ul><p> |
|
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|
9101 In case of success, <code>seek</code> returns the final file position, |
|
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|
9102 measured in bytes from the beginning of the file. |
|
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|
9103 If <code>seek</code> fails, it returns <b>nil</b>, |
|
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|
9104 plus a string describing the error. |
|
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|
9105 |
|
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diff
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|
9106 |
|
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|
9107 <p> |
|
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|
9108 The default value for <code>whence</code> is <code>"cur"</code>, |
|
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|
9109 and for <code>offset</code> is 0. |
|
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|
9110 Therefore, the call <code>file:seek()</code> returns the current |
|
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|
9111 file position, without changing it; |
|
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diff
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|
9112 the call <code>file:seek("set")</code> sets the position to the |
|
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changeset
|
9113 beginning of the file (and returns 0); |
|
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changeset
|
9114 and the call <code>file:seek("end")</code> sets the position to the |
|
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changeset
|
9115 end of the file, and returns its size. |
|
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|
9116 |
|
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parents:
diff
changeset
|
9117 |
|
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parents:
diff
changeset
|
9118 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9119 |
|
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|
9120 <p> |
|
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|
9121 <hr><h3><a name="pdf-file:setvbuf"><code>file:setvbuf (mode [, size])</code></a></h3> |
|
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|
9122 |
|
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parents:
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changeset
|
9123 |
|
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|
9124 <p> |
|
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|
9125 Sets the buffering mode for an output file. |
|
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|
9126 There are three available modes: |
|
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changeset
|
9127 |
|
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changeset
|
9128 <ul> |
|
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|
9129 |
|
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|
9130 <li><b>"<code>no</code>": </b> |
|
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changeset
|
9131 no buffering; the result of any output operation appears immediately. |
|
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changeset
|
9132 </li> |
|
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changeset
|
9133 |
|
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|
9134 <li><b>"<code>full</code>": </b> |
|
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changeset
|
9135 full buffering; output operation is performed only |
|
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changeset
|
9136 when the buffer is full or when |
|
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|
9137 you explicitly <code>flush</code> the file (see <a href="#pdf-io.flush"><code>io.flush</code></a>). |
|
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|
9138 </li> |
|
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changeset
|
9139 |
|
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|
9140 <li><b>"<code>line</code>": </b> |
|
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changeset
|
9141 line buffering; output is buffered until a newline is output |
|
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|
9142 or there is any input from some special files |
|
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|
9143 (such as a terminal device). |
|
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|
9144 </li> |
|
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changeset
|
9145 |
|
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|
9146 </ul><p> |
|
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|
9147 For the last two cases, <code>size</code> |
|
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|
9148 specifies the size of the buffer, in bytes. |
|
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changeset
|
9149 The default is an appropriate size. |
|
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changeset
|
9150 |
|
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changeset
|
9151 |
|
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changeset
|
9152 |
|
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changeset
|
9153 |
|
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|
9154 <p> |
|
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|
9155 <hr><h3><a name="pdf-file:write"><code>file:write (···)</code></a></h3> |
|
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|
9156 |
|
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changeset
|
9157 |
|
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|
9158 <p> |
|
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changeset
|
9159 Writes the value of each of its arguments to <code>file</code>. |
|
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|
9160 The arguments must be strings or numbers. |
|
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|
9161 |
|
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changeset
|
9162 |
|
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|
9163 <p> |
|
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|
9164 In case of success, this function returns <code>file</code>. |
|
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|
9165 Otherwise it returns <b>nil</b> plus a string describing the error. |
|
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|
9166 |
|
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diff
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|
9167 |
|
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diff
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|
9168 |
|
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diff
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|
9169 |
|
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diff
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|
9170 |
|
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diff
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|
9171 |
|
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|
9172 |
|
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|
9173 <h2>6.9 – <a name="6.9">Operating System Facilities</a></h2> |
|
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|
9174 |
|
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|
9175 <p> |
|
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|
9176 This library is implemented through table <a name="pdf-os"><code>os</code></a>. |
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|
9177 |
|
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|
9178 |
|
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9179 <p> |
|
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9180 <hr><h3><a name="pdf-os.clock"><code>os.clock ()</code></a></h3> |
|
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|
9181 |
|
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|
9182 |
|
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|
9183 <p> |
|
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|
9184 Returns an approximation of the amount in seconds of CPU time |
|
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|
9185 used by the program. |
|
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|
9186 |
|
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|
9187 |
|
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|
9188 |
|
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|
9189 |
|
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|
9190 <p> |
|
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|
9191 <hr><h3><a name="pdf-os.date"><code>os.date ([format [, time]])</code></a></h3> |
|
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|
9192 |
|
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|
9193 |
|
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9194 <p> |
|
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|
9195 Returns a string or a table containing date and time, |
|
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|
9196 formatted according to the given string <code>format</code>. |
|
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|
9197 |
|
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|
9198 |
|
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|
9199 <p> |
|
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|
9200 If the <code>time</code> argument is present, |
|
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|
9201 this is the time to be formatted |
|
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|
9202 (see the <a href="#pdf-os.time"><code>os.time</code></a> function for a description of this value). |
|
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|
9203 Otherwise, <code>date</code> formats the current time. |
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|
9204 |
|
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|
9205 |
|
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|
9206 <p> |
|
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|
9207 If <code>format</code> starts with '<code>!</code>', |
|
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|
9208 then the date is formatted in Coordinated Universal Time. |
|
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|
9209 After this optional character, |
|
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|
9210 if <code>format</code> is the string "<code>*t</code>", |
|
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9211 then <code>date</code> returns a table with the following fields: |
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|
9212 <code>year</code> (four digits), <code>month</code> (1–12), <code>day</code> (1–31), |
|
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9213 <code>hour</code> (0–23), <code>min</code> (0–59), <code>sec</code> (0–61), |
|
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9214 <code>wday</code> (weekday, Sunday is 1), |
|
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|
9215 <code>yday</code> (day of the year), |
|
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|
9216 and <code>isdst</code> (daylight saving flag, a boolean). |
|
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9217 This last field may be absent |
|
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|
9218 if the information is not available. |
|
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|
9219 |
|
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|
9220 |
|
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|
9221 <p> |
|
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|
9222 If <code>format</code> is not "<code>*t</code>", |
|
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|
9223 then <code>date</code> returns the date as a string, |
|
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|
9224 formatted according to the same rules as the ISO C function <code>strftime</code>. |
|
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|
9225 |
|
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|
9226 |
|
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|
9227 <p> |
|
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|
9228 When called without arguments, |
|
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|
9229 <code>date</code> returns a reasonable date and time representation that depends on |
|
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|
9230 the host system and on the current locale |
|
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|
9231 (that is, <code>os.date()</code> is equivalent to <code>os.date("%c")</code>). |
|
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|
9232 |
|
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|
9233 |
|
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|
9234 <p> |
|
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|
9235 On non-POSIX systems, |
|
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|
9236 this function may be not thread safe |
|
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|
9237 because of its reliance on C function <code>gmtime</code> and C function <code>localtime</code>. |
|
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|
9238 |
|
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|
9239 |
|
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|
9240 |
|
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|
9241 |
|
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|
9242 <p> |
|
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|
9243 <hr><h3><a name="pdf-os.difftime"><code>os.difftime (t2, t1)</code></a></h3> |
|
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|
9244 |
|
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|
9245 |
|
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|
9246 <p> |
|
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|
9247 Returns the difference, in seconds, |
|
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|
9248 from time <code>t1</code> to time <code>t2</code> |
|
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|
9249 (where the times are values returned by <a href="#pdf-os.time"><code>os.time</code></a>). |
|
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|
9250 In POSIX, Windows, and some other systems, |
|
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|
9251 this value is exactly <code>t2</code><em>-</em><code>t1</code>. |
|
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|
9252 |
|
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|
9253 |
|
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|
9254 |
|
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|
9255 |
|
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|
9256 <p> |
|
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|
9257 <hr><h3><a name="pdf-os.execute"><code>os.execute ([command])</code></a></h3> |
|
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|
9258 |
|
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|
9259 |
|
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|
9260 <p> |
|
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|
9261 This function is equivalent to the ISO C function <code>system</code>. |
|
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|
9262 It passes <code>command</code> to be executed by an operating system shell. |
|
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|
9263 Its first result is <b>true</b> |
|
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|
9264 if the command terminated successfully, |
|
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|
9265 or <b>nil</b> otherwise. |
|
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|
9266 After this first result |
|
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|
9267 the function returns a string plus a number, |
|
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|
9268 as follows: |
|
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changeset
|
9269 |
|
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|
9270 <ul> |
|
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|
9271 |
|
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|
9272 <li><b>"<code>exit</code>": </b> |
|
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|
9273 the command terminated normally; |
|
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|
9274 the following number is the exit status of the command. |
|
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|
9275 </li> |
|
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|
9276 |
|
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|
9277 <li><b>"<code>signal</code>": </b> |
|
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|
9278 the command was terminated by a signal; |
|
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|
9279 the following number is the signal that terminated the command. |
|
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|
9280 </li> |
|
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changeset
|
9281 |
|
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|
9282 </ul> |
|
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diff
changeset
|
9283 |
|
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parents:
diff
changeset
|
9284 <p> |
|
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parents:
diff
changeset
|
9285 When called without a <code>command</code>, |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
9286 <code>os.execute</code> returns a boolean that is true if a shell is available. |
|
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diff
changeset
|
9287 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9288 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9289 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9290 |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9291 <p> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
9292 <hr><h3><a name="pdf-os.exit"><code>os.exit ([code [, close]])</code></a></h3> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9293 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9294 |
|
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9295 <p> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
9296 Calls the ISO C function <code>exit</code> to terminate the host program. |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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|
9297 If <code>code</code> is <b>true</b>, |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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diff
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|
9298 the returned status is <code>EXIT_SUCCESS</code>; |
|
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diff
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|
9299 if <code>code</code> is <b>false</b>, |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
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|
9300 the returned status is <code>EXIT_FAILURE</code>; |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
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|
9301 if <code>code</code> is a number, |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
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|
9302 the returned status is this number. |
|
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parents:
diff
changeset
|
9303 The default value for <code>code</code> is <b>true</b>. |
|
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diff
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|
9304 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9305 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9306 <p> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
9307 If the optional second argument <code>close</code> is true, |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
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|
9308 closes the Lua state before exiting. |
|
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parents:
diff
changeset
|
9309 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9310 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9311 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9312 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
9313 <p> |
|
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parents:
diff
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|
9314 <hr><h3><a name="pdf-os.getenv"><code>os.getenv (varname)</code></a></h3> |
|
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diff
changeset
|
9315 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9316 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
9317 <p> |
|
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parents:
diff
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|
9318 Returns the value of the process environment variable <code>varname</code>, |
|
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parents:
diff
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|
9319 or <b>nil</b> if the variable is not defined. |
|
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parents:
diff
changeset
|
9320 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9321 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9322 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9323 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9324 <p> |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
9325 <hr><h3><a name="pdf-os.remove"><code>os.remove (filename)</code></a></h3> |
|
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parents:
diff
changeset
|
9326 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9327 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9328 <p> |
|
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parents:
diff
changeset
|
9329 Deletes the file (or empty directory, on POSIX systems) |
|
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diff
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|
9330 with the given name. |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
9331 If this function fails, it returns <b>nil</b>, |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
9332 plus a string describing the error and the error code. |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9333 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9334 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9335 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9336 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9337 <p> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9338 <hr><h3><a name="pdf-os.rename"><code>os.rename (oldname, newname)</code></a></h3> |
|
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parents:
diff
changeset
|
9339 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9340 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9341 <p> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9342 Renames file or directory named <code>oldname</code> to <code>newname</code>. |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9343 If this function fails, it returns <b>nil</b>, |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9344 plus a string describing the error and the error code. |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9345 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9346 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9347 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9348 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9349 <p> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9350 <hr><h3><a name="pdf-os.setlocale"><code>os.setlocale (locale [, category])</code></a></h3> |
|
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parents:
diff
changeset
|
9351 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9352 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9353 <p> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9354 Sets the current locale of the program. |
|
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parents:
diff
changeset
|
9355 <code>locale</code> is a system-dependent string specifying a locale; |
|
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parents:
diff
changeset
|
9356 <code>category</code> is an optional string describing which category to change: |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
9357 <code>"all"</code>, <code>"collate"</code>, <code>"ctype"</code>, |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9358 <code>"monetary"</code>, <code>"numeric"</code>, or <code>"time"</code>; |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9359 the default category is <code>"all"</code>. |
|
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parents:
diff
changeset
|
9360 The function returns the name of the new locale, |
|
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parents:
diff
changeset
|
9361 or <b>nil</b> if the request cannot be honored. |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9362 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9363 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9364 <p> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9365 If <code>locale</code> is the empty string, |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
9366 the current locale is set to an implementation-defined native locale. |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9367 If <code>locale</code> is the string "<code>C</code>", |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9368 the current locale is set to the standard C locale. |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9369 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9370 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9371 <p> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9372 When called with <b>nil</b> as the first argument, |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9373 this function only returns the name of the current locale |
|
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parents:
diff
changeset
|
9374 for the given category. |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9375 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9376 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9377 <p> |
|
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parents:
diff
changeset
|
9378 This function may be not thread safe |
|
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parents:
diff
changeset
|
9379 because of its reliance on C function <code>setlocale</code>. |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9380 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9381 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9382 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9383 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9384 <p> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9385 <hr><h3><a name="pdf-os.time"><code>os.time ([table])</code></a></h3> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9386 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9387 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9388 <p> |
|
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parents:
diff
changeset
|
9389 Returns the current time when called without arguments, |
|
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parents:
diff
changeset
|
9390 or a time representing the date and time specified by the given table. |
|
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diff
changeset
|
9391 This table must have fields <code>year</code>, <code>month</code>, and <code>day</code>, |
|
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diff
changeset
|
9392 and may have fields |
|
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parents:
diff
changeset
|
9393 <code>hour</code> (default is 12), |
|
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parents:
diff
changeset
|
9394 <code>min</code> (default is 0), |
|
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parents:
diff
changeset
|
9395 <code>sec</code> (default is 0), |
|
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parents:
diff
changeset
|
9396 and <code>isdst</code> (default is <b>nil</b>). |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9397 For a description of these fields, see the <a href="#pdf-os.date"><code>os.date</code></a> function. |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9398 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9399 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9400 <p> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9401 The returned value is a number, whose meaning depends on your system. |
|
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|
9402 In POSIX, Windows, and some other systems, |
|
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|
9403 this number counts the number |
|
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|
9404 of seconds since some given start time (the "epoch"). |
|
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|
9405 In other systems, the meaning is not specified, |
|
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|
9406 and the number returned by <code>time</code> can be used only as an argument to |
|
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|
9407 <a href="#pdf-os.date"><code>os.date</code></a> and <a href="#pdf-os.difftime"><code>os.difftime</code></a>. |
|
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|
9408 |
|
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|
9409 |
|
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|
9410 |
|
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|
9411 |
|
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|
9412 <p> |
|
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|
9413 <hr><h3><a name="pdf-os.tmpname"><code>os.tmpname ()</code></a></h3> |
|
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|
9414 |
|
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|
9415 |
|
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|
9416 <p> |
|
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|
9417 Returns a string with a file name that can |
|
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|
9418 be used for a temporary file. |
|
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|
9419 The file must be explicitly opened before its use |
|
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|
9420 and explicitly removed when no longer needed. |
|
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|
9421 |
|
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diff
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|
9422 |
|
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|
9423 <p> |
|
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|
9424 On POSIX systems, |
|
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|
9425 this function also creates a file with that name, |
|
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|
9426 to avoid security risks. |
|
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|
9427 (Someone else might create the file with wrong permissions |
|
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|
9428 in the time between getting the name and creating the file.) |
|
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|
9429 You still have to open the file to use it |
|
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|
9430 and to remove it (even if you do not use it). |
|
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|
9431 |
|
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diff
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|
9432 |
|
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|
9433 <p> |
|
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|
9434 When possible, |
|
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|
9435 you may prefer to use <a href="#pdf-io.tmpfile"><code>io.tmpfile</code></a>, |
|
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|
9436 which automatically removes the file when the program ends. |
|
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|
9437 |
|
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diff
changeset
|
9438 |
|
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diff
changeset
|
9439 |
|
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diff
changeset
|
9440 |
|
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diff
changeset
|
9441 |
|
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diff
changeset
|
9442 |
|
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|
9443 |
|
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|
9444 <h2>6.10 – <a name="6.10">The Debug Library</a></h2> |
|
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|
9445 |
|
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|
9446 <p> |
|
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|
9447 This library provides |
|
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|
9448 the functionality of the debug interface (<a href="#4.9">§4.9</a>) to Lua programs. |
|
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|
9449 You should exert care when using this library. |
|
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|
9450 Several of its functions |
|
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|
9451 violate basic assumptions about Lua code |
|
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|
9452 (e.g., that variables local to a function |
|
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|
9453 cannot be accessed from outside; |
|
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|
9454 that userdata metatables cannot be changed by Lua code; |
|
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|
9455 that Lua programs do not crash) |
|
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|
9456 and therefore can compromise otherwise secure code. |
|
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|
9457 Moreover, some functions in this library may be slow. |
|
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|
9458 |
|
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|
9459 |
|
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|
9460 <p> |
|
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|
9461 All functions in this library are provided |
|
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|
9462 inside the <a name="pdf-debug"><code>debug</code></a> table. |
|
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|
9463 All functions that operate over a thread |
|
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|
9464 have an optional first argument which is the |
|
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changeset
|
9465 thread to operate over. |
|
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|
9466 The default is always the current thread. |
|
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|
9467 |
|
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changeset
|
9468 |
|
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|
9469 <p> |
|
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|
9470 <hr><h3><a name="pdf-debug.debug"><code>debug.debug ()</code></a></h3> |
|
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|
9471 |
|
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changeset
|
9472 |
|
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|
9473 <p> |
|
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|
9474 Enters an interactive mode with the user, |
|
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|
9475 running each string that the user enters. |
|
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|
9476 Using simple commands and other debug facilities, |
|
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changeset
|
9477 the user can inspect global and local variables, |
|
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|
9478 change their values, evaluate expressions, and so on. |
|
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|
9479 A line containing only the word <code>cont</code> finishes this function, |
|
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changeset
|
9480 so that the caller continues its execution. |
|
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changeset
|
9481 |
|
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changeset
|
9482 |
|
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|
9483 <p> |
|
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changeset
|
9484 Note that commands for <code>debug.debug</code> are not lexically nested |
|
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changeset
|
9485 within any function and so have no direct access to local variables. |
|
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changeset
|
9486 |
|
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changeset
|
9487 |
|
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changeset
|
9488 |
|
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changeset
|
9489 |
|
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changeset
|
9490 <p> |
|
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changeset
|
9491 <hr><h3><a name="pdf-debug.gethook"><code>debug.gethook ([thread])</code></a></h3> |
|
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changeset
|
9492 |
|
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changeset
|
9493 |
|
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|
9494 <p> |
|
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changeset
|
9495 Returns the current hook settings of the thread, as three values: |
|
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changeset
|
9496 the current hook function, the current hook mask, |
|
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|
9497 and the current hook count |
|
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|
9498 (as set by the <a href="#pdf-debug.sethook"><code>debug.sethook</code></a> function). |
|
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changeset
|
9499 |
|
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changeset
|
9500 |
|
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changeset
|
9501 |
|
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changeset
|
9502 |
|
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|
9503 <p> |
|
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|
9504 <hr><h3><a name="pdf-debug.getinfo"><code>debug.getinfo ([thread,] f [, what])</code></a></h3> |
|
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|
9505 |
|
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changeset
|
9506 |
|
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|
9507 <p> |
|
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changeset
|
9508 Returns a table with information about a function. |
|
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changeset
|
9509 You can give the function directly |
|
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|
9510 or you can give a number as the value of <code>f</code>, |
|
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|
9511 which means the function running at level <code>f</code> of the call stack |
|
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|
9512 of the given thread: |
|
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changeset
|
9513 level 0 is the current function (<code>getinfo</code> itself); |
|
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changeset
|
9514 level 1 is the function that called <code>getinfo</code> |
|
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changeset
|
9515 (except for tail calls, which do not count on the stack); |
|
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changeset
|
9516 and so on. |
|
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changeset
|
9517 If <code>f</code> is a number larger than the number of active functions, |
|
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changeset
|
9518 then <code>getinfo</code> returns <b>nil</b>. |
|
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changeset
|
9519 |
|
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changeset
|
9520 |
|
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diff
changeset
|
9521 <p> |
|
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diff
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|
9522 The returned table can contain all the fields returned by <a href="#lua_getinfo"><code>lua_getinfo</code></a>, |
|
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diff
changeset
|
9523 with the string <code>what</code> describing which fields to fill in. |
|
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parents:
diff
changeset
|
9524 The default for <code>what</code> is to get all information available, |
|
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parents:
diff
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|
9525 except the table of valid lines. |
|
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parents:
diff
changeset
|
9526 If present, |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9527 the option '<code>f</code>' |
|
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parents:
diff
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|
9528 adds a field named <code>func</code> with the function itself. |
|
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parents:
diff
changeset
|
9529 If present, |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9530 the option '<code>L</code>' |
|
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diff
changeset
|
9531 adds a field named <code>activelines</code> with the table of |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
9532 valid lines. |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9533 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9534 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9535 <p> |
|
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parents:
diff
changeset
|
9536 For instance, the expression <code>debug.getinfo(1,"n").name</code> returns |
|
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parents:
diff
changeset
|
9537 a table with a name for the current function, |
|
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parents:
diff
changeset
|
9538 if a reasonable name can be found, |
|
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9539 and the expression <code>debug.getinfo(print)</code> |
|
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
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|
9540 returns a table with all available information |
|
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diff
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|
9541 about the <a href="#pdf-print"><code>print</code></a> function. |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9542 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9543 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9544 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9545 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9546 <p> |
|
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diff
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|
9547 <hr><h3><a name="pdf-debug.getlocal"><code>debug.getlocal ([thread,] f, local)</code></a></h3> |
|
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changeset
|
9548 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9549 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9550 <p> |
|
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parents:
diff
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|
9551 This function returns the name and the value of the local variable |
|
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diff
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|
9552 with index <code>local</code> of the function at level <code>f</code> of the stack. |
|
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diff
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|
9553 This function accesses not only explicit local variables, |
|
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diff
changeset
|
9554 but also parameters, temporaries, etc. |
|
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parents:
diff
changeset
|
9555 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9556 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9557 <p> |
|
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diff
changeset
|
9558 The first parameter or local variable has index 1, and so on, |
|
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parents:
diff
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|
9559 following the order that they are declared in the code, |
|
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parents:
diff
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|
9560 counting only the variables that are active |
|
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parents:
diff
changeset
|
9561 in the current scope of the function. |
|
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parents:
diff
changeset
|
9562 Negative indices refer to vararg parameters; |
|
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parents:
diff
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|
9563 -1 is the first vararg parameter. |
|
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parents:
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|
9564 The function returns <b>nil</b> if there is no variable with the given index, |
|
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parents:
diff
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|
9565 and raises an error when called with a level out of range. |
|
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diff
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|
9566 (You can call <a href="#pdf-debug.getinfo"><code>debug.getinfo</code></a> to check whether the level is valid.) |
|
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changeset
|
9567 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9568 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9569 <p> |
|
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parents:
diff
changeset
|
9570 Variable names starting with '<code>(</code>' (open parenthesis) |
|
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parents:
diff
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|
9571 represent variables with no known names |
|
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parents:
diff
changeset
|
9572 (internal variables such as loop control variables, |
|
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parents:
diff
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|
9573 and variables from chunks saved without debug information). |
|
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parents:
diff
changeset
|
9574 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9575 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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changeset
|
9576 <p> |
|
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|
9577 The parameter <code>f</code> may also be a function. |
|
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diff
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|
9578 In that case, <code>getlocal</code> returns only the name of function parameters. |
|
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changeset
|
9579 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9580 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9581 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9582 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9583 <p> |
|
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parents:
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|
9584 <hr><h3><a name="pdf-debug.getmetatable"><code>debug.getmetatable (value)</code></a></h3> |
|
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parents:
diff
changeset
|
9585 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9586 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9587 <p> |
|
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parents:
diff
changeset
|
9588 Returns the metatable of the given <code>value</code> |
|
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parents:
diff
changeset
|
9589 or <b>nil</b> if it does not have a metatable. |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9590 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9591 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9592 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9593 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9594 <p> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9595 <hr><h3><a name="pdf-debug.getregistry"><code>debug.getregistry ()</code></a></h3> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9596 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9597 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9598 <p> |
|
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parents:
diff
changeset
|
9599 Returns the registry table (see <a href="#4.5">§4.5</a>). |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9600 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9601 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9602 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9603 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9604 <p> |
|
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parents:
diff
changeset
|
9605 <hr><h3><a name="pdf-debug.getupvalue"><code>debug.getupvalue (f, up)</code></a></h3> |
|
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parents:
diff
changeset
|
9606 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9607 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9608 <p> |
|
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parents:
diff
changeset
|
9609 This function returns the name and the value of the upvalue |
|
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diff
changeset
|
9610 with index <code>up</code> of the function <code>f</code>. |
|
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diff
changeset
|
9611 The function returns <b>nil</b> if there is no upvalue with the given index. |
|
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parents:
diff
changeset
|
9612 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9613 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9614 <p> |
|
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diff
changeset
|
9615 Variable names starting with '<code>(</code>' (open parenthesis) |
|
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parents:
diff
changeset
|
9616 represent variables with no known names |
|
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parents:
diff
changeset
|
9617 (variables from chunks saved without debug information). |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9618 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9619 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9620 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9621 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9622 <p> |
|
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parents:
diff
changeset
|
9623 <hr><h3><a name="pdf-debug.getuservalue"><code>debug.getuservalue (u)</code></a></h3> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9624 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9625 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9626 <p> |
|
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parents:
diff
changeset
|
9627 Returns the Lua value associated to <code>u</code>. |
|
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parents:
diff
changeset
|
9628 If <code>u</code> is not a userdata, |
|
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parents:
diff
changeset
|
9629 returns <b>nil</b>. |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9630 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9631 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9632 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9633 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9634 <p> |
|
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parents:
diff
changeset
|
9635 <hr><h3><a name="pdf-debug.sethook"><code>debug.sethook ([thread,] hook, mask [, count])</code></a></h3> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9636 |
|
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9637 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9638 <p> |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9639 Sets the given function as a hook. |
|
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|
9640 The string <code>mask</code> and the number <code>count</code> describe |
|
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|
9641 when the hook will be called. |
|
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|
9642 The string mask may have any combination of the following characters, |
|
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|
9643 with the given meaning: |
|
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|
9644 |
|
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diff
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|
9645 <ul> |
|
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|
9646 <li><b>'<code>c</code>': </b> the hook is called every time Lua calls a function;</li> |
|
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|
9647 <li><b>'<code>r</code>': </b> the hook is called every time Lua returns from a function;</li> |
|
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|
9648 <li><b>'<code>l</code>': </b> the hook is called every time Lua enters a new line of code.</li> |
|
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|
9649 </ul><p> |
|
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|
9650 Moreover, |
|
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|
9651 with a <code>count</code> different from zero, |
|
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|
9652 the hook is called also after every <code>count</code> instructions. |
|
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|
9653 |
|
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diff
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|
9654 |
|
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|
9655 <p> |
|
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|
9656 When called without arguments, |
|
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|
9657 <a href="#pdf-debug.sethook"><code>debug.sethook</code></a> turns off the hook. |
|
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|
9658 |
|
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|
9659 |
|
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|
9660 <p> |
|
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|
9661 When the hook is called, its first parameter is a string |
|
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|
9662 describing the event that has triggered its call: |
|
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|
9663 <code>"call"</code> (or <code>"tail call"</code>), |
|
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|
9664 <code>"return"</code>, |
|
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|
9665 <code>"line"</code>, and <code>"count"</code>. |
|
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|
9666 For line events, |
|
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|
9667 the hook also gets the new line number as its second parameter. |
|
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|
9668 Inside a hook, |
|
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|
9669 you can call <code>getinfo</code> with level 2 to get more information about |
|
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|
9670 the running function |
|
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|
9671 (level 0 is the <code>getinfo</code> function, |
|
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|
9672 and level 1 is the hook function). |
|
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|
9673 |
|
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|
9674 |
|
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|
9675 |
|
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|
9676 |
|
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|
9677 <p> |
|
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|
9678 <hr><h3><a name="pdf-debug.setlocal"><code>debug.setlocal ([thread,] level, local, value)</code></a></h3> |
|
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|
9679 |
|
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|
9680 |
|
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|
9681 <p> |
|
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|
9682 This function assigns the value <code>value</code> to the local variable |
|
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|
9683 with index <code>local</code> of the function at level <code>level</code> of the stack. |
|
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|
9684 The function returns <b>nil</b> if there is no local |
|
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|
9685 variable with the given index, |
|
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|
9686 and raises an error when called with a <code>level</code> out of range. |
|
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|
9687 (You can call <code>getinfo</code> to check whether the level is valid.) |
|
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|
9688 Otherwise, it returns the name of the local variable. |
|
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|
9689 |
|
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|
9690 |
|
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|
9691 <p> |
|
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|
9692 See <a href="#pdf-debug.getlocal"><code>debug.getlocal</code></a> for more information about |
|
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|
9693 variable indices and names. |
|
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|
9694 |
|
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|
9695 |
|
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|
9696 |
|
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|
9697 |
|
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|
9698 <p> |
|
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|
9699 <hr><h3><a name="pdf-debug.setmetatable"><code>debug.setmetatable (value, table)</code></a></h3> |
|
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|
9700 |
|
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changeset
|
9701 |
|
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|
9702 <p> |
|
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|
9703 Sets the metatable for the given <code>value</code> to the given <code>table</code> |
|
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|
9704 (which can be <b>nil</b>). |
|
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|
9705 Returns <code>value</code>. |
|
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|
9706 |
|
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|
9707 |
|
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|
9708 |
|
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|
9709 |
|
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|
9710 <p> |
|
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|
9711 <hr><h3><a name="pdf-debug.setupvalue"><code>debug.setupvalue (f, up, value)</code></a></h3> |
|
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|
9712 |
|
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|
9713 |
|
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|
9714 <p> |
|
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|
9715 This function assigns the value <code>value</code> to the upvalue |
|
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|
9716 with index <code>up</code> of the function <code>f</code>. |
|
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|
9717 The function returns <b>nil</b> if there is no upvalue |
|
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|
9718 with the given index. |
|
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|
9719 Otherwise, it returns the name of the upvalue. |
|
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changeset
|
9720 |
|
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diff
changeset
|
9721 |
|
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diff
changeset
|
9722 |
|
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changeset
|
9723 |
|
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|
9724 <p> |
|
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|
9725 <hr><h3><a name="pdf-debug.setuservalue"><code>debug.setuservalue (udata, value)</code></a></h3> |
|
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changeset
|
9726 |
|
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changeset
|
9727 |
|
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|
9728 <p> |
|
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|
9729 Sets the given <code>value</code> as |
|
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|
9730 the Lua value associated to the given <code>udata</code>. |
|
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|
9731 <code>udata</code> must be a full userdata. |
|
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changeset
|
9732 |
|
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changeset
|
9733 |
|
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|
9734 <p> |
|
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|
9735 Returns <code>udata</code>. |
|
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changeset
|
9736 |
|
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changeset
|
9737 |
|
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diff
changeset
|
9738 |
|
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changeset
|
9739 |
|
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|
9740 <p> |
|
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|
9741 <hr><h3><a name="pdf-debug.traceback"><code>debug.traceback ([thread,] [message [, level]])</code></a></h3> |
|
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changeset
|
9742 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9743 |
|
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changeset
|
9744 <p> |
|
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changeset
|
9745 If <code>message</code> is present but is neither a string nor <b>nil</b>, |
|
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changeset
|
9746 this function returns <code>message</code> without further processing. |
|
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changeset
|
9747 Otherwise, |
|
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changeset
|
9748 it returns a string with a traceback of the call stack. |
|
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changeset
|
9749 The optional <code>message</code> string is appended |
|
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|
9750 at the beginning of the traceback. |
|
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changeset
|
9751 An optional <code>level</code> number tells at which level |
|
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changeset
|
9752 to start the traceback |
|
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diff
changeset
|
9753 (default is 1, the function calling <code>traceback</code>). |
|
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changeset
|
9754 |
|
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diff
changeset
|
9755 |
|
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changeset
|
9756 |
|
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changeset
|
9757 |
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9758 <p> |
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9759 <hr><h3><a name="pdf-debug.upvalueid"><code>debug.upvalueid (f, n)</code></a></h3> |
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9760 |
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9761 |
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9762 <p> |
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9763 Returns a unique identifier (as a light userdata) |
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9764 for the upvalue numbered <code>n</code> |
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9765 from the given function. |
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9766 |
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9767 |
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9768 <p> |
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9769 These unique identifiers allow a program to check whether different |
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9770 closures share upvalues. |
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|
9771 Lua closures that share an upvalue |
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9772 (that is, that access a same external local variable) |
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9773 will return identical ids for those upvalue indices. |
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9774 |
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|
9775 |
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|
9776 |
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|
9777 |
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|
9778 <p> |
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|
9779 <hr><h3><a name="pdf-debug.upvaluejoin"><code>debug.upvaluejoin (f1, n1, f2, n2)</code></a></h3> |
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9780 |
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9781 |
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9782 <p> |
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9783 Make the <code>n1</code>-th upvalue of the Lua closure <code>f1</code> |
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|
9784 refer to the <code>n2</code>-th upvalue of the Lua closure <code>f2</code>. |
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9785 |
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|
9786 |
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|
9787 |
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|
9788 |
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|
9789 |
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|
9790 |
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|
9791 |
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|
9792 <h1>7 – <a name="7">Lua Standalone</a></h1> |
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9793 |
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9794 <p> |
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9795 Although Lua has been designed as an extension language, |
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9796 to be embedded in a host C program, |
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9797 it is also frequently used as a standalone language. |
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9798 An interpreter for Lua as a standalone language, |
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9799 called simply <code>lua</code>, |
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9800 is provided with the standard distribution. |
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9801 The standalone interpreter includes |
|
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9802 all standard libraries, including the debug library. |
|
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9803 Its usage is: |
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9804 |
|
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|
9805 <pre> |
|
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9806 lua [options] [script [args]] |
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9807 </pre><p> |
|
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9808 The options are: |
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9809 |
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9810 <ul> |
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9811 <li><b><code>-e <em>stat</em></code>: </b> executes string <em>stat</em>;</li> |
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9812 <li><b><code>-l <em>mod</em></code>: </b> "requires" <em>mod</em>;</li> |
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9813 <li><b><code>-i</code>: </b> enters interactive mode after running <em>script</em>;</li> |
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9814 <li><b><code>-v</code>: </b> prints version information;</li> |
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9815 <li><b><code>-E</code>: </b> ignores environment variables;</li> |
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9816 <li><b><code>--</code>: </b> stops handling options;</li> |
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9817 <li><b><code>-</code>: </b> executes <code>stdin</code> as a file and stops handling options.</li> |
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9818 </ul><p> |
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9819 After handling its options, <code>lua</code> runs the given <em>script</em>. |
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9820 When called without arguments, |
|
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|
9821 <code>lua</code> behaves as <code>lua -v -i</code> |
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9822 when the standard input (<code>stdin</code>) is a terminal, |
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9823 and as <code>lua -</code> otherwise. |
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9824 |
|
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|
9825 |
|
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|
9826 <p> |
|
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|
9827 When called without option <code>-E</code>, |
|
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9828 the interpreter checks for an environment variable <a name="pdf-LUA_INIT_5_3"><code>LUA_INIT_5_3</code></a> |
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9829 (or <a name="pdf-LUA_INIT"><code>LUA_INIT</code></a> if the versioned name is not defined) |
|
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9830 before running any argument. |
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|
9831 If the variable content has the format <code>@<em>filename</em></code>, |
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9832 then <code>lua</code> executes the file. |
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9833 Otherwise, <code>lua</code> executes the string itself. |
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|
9834 |
|
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|
9835 |
|
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|
9836 <p> |
|
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|
9837 When called with option <code>-E</code>, |
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9838 besides ignoring <code>LUA_INIT</code>, |
|
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|
9839 Lua also ignores |
|
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|
9840 the values of <code>LUA_PATH</code> and <code>LUA_CPATH</code>, |
|
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|
9841 setting the values of |
|
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|
9842 <a href="#pdf-package.path"><code>package.path</code></a> and <a href="#pdf-package.cpath"><code>package.cpath</code></a> |
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|
9843 with the default paths defined in <code>luaconf.h</code>. |
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|
9844 |
|
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|
9845 |
|
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|
9846 <p> |
|
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|
9847 All options are handled in order, except <code>-i</code> and <code>-E</code>. |
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9848 For instance, an invocation like |
|
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|
9849 |
|
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|
9850 <pre> |
|
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|
9851 $ lua -e'a=1' -e 'print(a)' script.lua |
|
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9852 </pre><p> |
|
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|
9853 will first set <code>a</code> to 1, then print the value of <code>a</code>, |
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9854 and finally run the file <code>script.lua</code> with no arguments. |
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|
9855 (Here <code>$</code> is the shell prompt. Your prompt may be different.) |
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9856 |
|
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|
9857 |
|
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|
9858 <p> |
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9859 Before running any code, |
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9860 <code>lua</code> collects all command-line arguments |
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9861 in a global table called <code>arg</code>. |
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9862 The script name goes to index 0, |
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9863 the first argument after the script name goes to index 1, |
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9864 and so on. |
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9865 Any arguments before the script name |
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|
9866 (that is, the interpreter name plus its options) |
|
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9867 go to negative indices. |
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9868 For instance, in the call |
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|
9869 |
|
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|
9870 <pre> |
|
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9871 $ lua -la b.lua t1 t2 |
|
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9872 </pre><p> |
|
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|
9873 the table is like this: |
|
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|
9874 |
|
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diff
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|
9875 <pre> |
|
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diff
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|
9876 arg = { [-2] = "lua", [-1] = "-la", |
|
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|
9877 [0] = "b.lua", |
|
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|
9878 [1] = "t1", [2] = "t2" } |
|
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|
9879 </pre><p> |
|
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diff
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|
9880 If there is no script in the call, |
|
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parents:
diff
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|
9881 the interpreter name goes to index 0, |
|
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diff
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|
9882 followed by the other arguments. |
|
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diff
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|
9883 For instance, the call |
|
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diff
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|
9884 |
|
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diff
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|
9885 <pre> |
|
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diff
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|
9886 $ lua -e "print(arg[1])" |
|
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|
9887 </pre><p> |
|
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|
9888 will print "<code>-e</code>". |
|
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parents:
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|
9889 If there is a script, |
|
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diff
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|
9890 the script is called with parameters |
|
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diff
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|
9891 <code>arg[1]</code>, ···, <code>arg[#arg]</code>. |
|
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|
9892 (Like all chunks in Lua, |
|
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|
9893 the script is compiled as a vararg function.) |
|
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parents:
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|
9894 |
|
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diff
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|
9895 |
|
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|
9896 <p> |
|
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|
9897 In interactive mode, |
|
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diff
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|
9898 Lua repeatedly prompts and waits for a line. |
|
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|
9899 After reading a line, |
|
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parents:
diff
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|
9900 Lua first try to interpret the line as an expression. |
|
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parents:
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|
9901 If it succeeds, it prints its value. |
|
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parents:
diff
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|
9902 Otherwise, it interprets the line as a statement. |
|
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parents:
diff
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|
9903 If you write an incomplete statement, |
|
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parents:
diff
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|
9904 the interpreter waits for its completion |
|
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parents:
diff
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|
9905 by issuing a different prompt. |
|
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diff
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|
9906 |
|
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diff
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|
9907 |
|
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|
9908 <p> |
|
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parents:
diff
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|
9909 In case of unprotected errors in the script, |
|
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parents:
diff
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|
9910 the interpreter reports the error to the standard error stream. |
|
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parents:
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|
9911 If the error object is not a string but |
|
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parents:
diff
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|
9912 has a metamethod <code>__tostring</code>, |
|
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parents:
diff
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|
9913 the interpreter calls this metamethod to produce the final message. |
|
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parents:
diff
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|
9914 Otherwise, the interpreter converts the error object to a string |
|
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|
9915 and adds a stack traceback to it. |
|
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|
9916 |
|
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diff
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|
9917 |
|
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diff
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|
9918 <p> |
|
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|
9919 When finishing normally, |
|
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|
9920 the interpreter closes its main Lua state |
|
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|
9921 (see <a href="#lua_close"><code>lua_close</code></a>). |
|
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|
9922 The script can avoid this step by |
|
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diff
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|
9923 calling <a href="#pdf-os.exit"><code>os.exit</code></a> to terminate. |
|
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|
9924 |
|
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diff
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|
9925 |
|
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|
9926 <p> |
|
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|
9927 To allow the use of Lua as a |
|
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parents:
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|
9928 script interpreter in Unix systems, |
|
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|
9929 the standalone interpreter skips |
|
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diff
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|
9930 the first line of a chunk if it starts with <code>#</code>. |
|
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parents:
diff
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|
9931 Therefore, Lua scripts can be made into executable programs |
|
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parents:
diff
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|
9932 by using <code>chmod +x</code> and the <code>#!</code> form, |
|
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|
9933 as in |
|
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parents:
diff
changeset
|
9934 |
|
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diff
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|
9935 <pre> |
|
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|
9936 #!/usr/local/bin/lua |
|
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|
9937 </pre><p> |
|
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|
9938 (Of course, |
|
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parents:
diff
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|
9939 the location of the Lua interpreter may be different in your machine. |
|
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diff
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|
9940 If <code>lua</code> is in your <code>PATH</code>, |
|
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|
9941 then |
|
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parents:
diff
changeset
|
9942 |
|
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parents:
diff
changeset
|
9943 <pre> |
|
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parents:
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changeset
|
9944 #!/usr/bin/env lua |
|
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parents:
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changeset
|
9945 </pre><p> |
|
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parents:
diff
changeset
|
9946 is a more portable solution.) |
|
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parents:
diff
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|
9947 |
|
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parents:
diff
changeset
|
9948 |
|
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
9949 |
|
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diff
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|
9950 <h1>8 – <a name="8">Incompatibilities with the Previous Version</a></h1> |
|
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|
9951 |
|
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diff
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|
9952 <p> |
|
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parents:
diff
changeset
|
9953 Here we list the incompatibilities that you may find when moving a program |
|
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parents:
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changeset
|
9954 from Lua 5.2 to Lua 5.3. |
|
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|
9955 You can avoid some incompatibilities by compiling Lua with |
|
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|
9956 appropriate options (see file <code>luaconf.h</code>). |
|
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|
9957 However, |
|
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parents:
diff
changeset
|
9958 all these compatibility options will be removed in the future. |
|
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parents:
diff
changeset
|
9959 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9960 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9961 <p> |
|
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parents:
diff
changeset
|
9962 Lua versions can always change the C API in ways that |
|
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parents:
diff
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|
9963 do not imply source-code changes in a program, |
|
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parents:
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|
9964 such as the numeric values for constants |
|
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|
9965 or the implementation of functions as macros. |
|
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|
9966 Therefore, |
|
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parents:
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changeset
|
9967 you should not assume that binaries are compatible between |
|
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changeset
|
9968 different Lua versions. |
|
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parents:
diff
changeset
|
9969 Always recompile clients of the Lua API when |
|
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diff
changeset
|
9970 using a new version. |
|
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changeset
|
9971 |
|
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parents:
diff
changeset
|
9972 |
|
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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changeset
|
9973 <p> |
|
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parents:
diff
changeset
|
9974 Similarly, Lua versions can always change the internal representation |
|
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changeset
|
9975 of precompiled chunks; |
|
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parents:
diff
changeset
|
9976 precompiled chunks are not compatible between different Lua versions. |
|
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parents:
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changeset
|
9977 |
|
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parents:
diff
changeset
|
9978 |
|
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parents:
diff
changeset
|
9979 <p> |
|
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parents:
diff
changeset
|
9980 The standard paths in the official distribution may |
|
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changeset
|
9981 change between versions. |
|
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parents:
diff
changeset
|
9982 |
|
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parents:
diff
changeset
|
9983 |
|
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diff
changeset
|
9984 |
|
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parents:
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changeset
|
9985 <h2>8.1 – <a name="8.1">Changes in the Language</a></h2> |
|
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parents:
diff
changeset
|
9986 <ul> |
|
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parents:
diff
changeset
|
9987 |
|
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parents:
diff
changeset
|
9988 <li> |
|
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parents:
diff
changeset
|
9989 The main difference between Lua 5.2 and Lua 5.3 is the |
|
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parents:
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changeset
|
9990 introduction of an integer subtype for numbers. |
|
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parents:
diff
changeset
|
9991 Although this change should not affect "normal" computations, |
|
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parents:
diff
changeset
|
9992 some computations |
|
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parents:
diff
changeset
|
9993 (mainly those that involve some kind of overflow) |
|
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|
9994 can give different results. |
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9995 |
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9996 |
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9997 <p> |
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9998 You can fix these differences by forcing a number to be a float |
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9999 (in Lua 5.2 all numbers were float), |
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10000 in particular writing constants with an ending <code>.0</code> |
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10001 or using <code>x = x + 0.0</code> to convert a variable. |
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10002 (This recommendation is only for a quick fix |
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|
10003 for an occasional incompatibility; |
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10004 it is not a general guideline for good programming. |
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10005 For good programming, |
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10006 use floats where you need floats |
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10007 and integers where you need integers.) |
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10008 </li> |
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10009 |
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10010 <li> |
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10011 The conversion of a float to a string now adds a <code>.0</code> suffix |
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10012 to the result if it looks like an integer. |
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|
10013 (For instance, the float 2.0 will be printed as <code>2.0</code>, |
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10014 not as <code>2</code>.) |
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10015 You should always use an explicit format |
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10016 when you need a specific format for numbers. |
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10017 |
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10018 |
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10019 <p> |
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10020 (Formally this is not an incompatibility, |
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10021 because Lua does not specify how numbers are formatted as strings, |
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10022 but some programs assumed a specific format.) |
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10023 </li> |
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10024 |
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10025 <li> |
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|
10026 The generational mode for the garbage collector was removed. |
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|
10027 (It was an experimental feature in Lua 5.2.) |
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|
10028 </li> |
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10029 |
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|
10030 </ul> |
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|
10031 |
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|
10032 |
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|
10033 |
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|
10034 |
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|
10035 <h2>8.2 – <a name="8.2">Changes in the Libraries</a></h2> |
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10036 <ul> |
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10037 |
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10038 <li> |
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|
10039 The <code>bit32</code> library has been deprecated. |
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|
10040 It is easy to require a compatible external library or, |
|
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10041 better yet, to replace its functions with appropriate bitwise operations. |
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|
10042 (Keep in mind that <code>bit32</code> operates on 32-bit integers, |
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10043 while the bitwise operators in standard Lua operate on 64-bit integers.) |
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10044 </li> |
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|
10045 |
|
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10046 <li> |
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|
10047 The Table library now respects metamethods |
|
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|
10048 for setting and getting elements. |
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|
10049 </li> |
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|
10050 |
|
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10051 <li> |
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|
10052 The <a href="#pdf-ipairs"><code>ipairs</code></a> iterator now respects metamethods and |
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|
10053 its <code>__ipairs</code> metamethod has been deprecated. |
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10054 </li> |
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|
10055 |
|
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|
10056 <li> |
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|
10057 Option names in <a href="#pdf-io.read"><code>io.read</code></a> do not have a starting '<code>*</code>' anymore. |
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|
10058 For compatibility, Lua will continue to ignore this character. |
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|
10059 </li> |
|
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|
10060 |
|
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|
10061 <li> |
|
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|
10062 The following functions were deprecated in the mathematical library: |
|
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|
10063 <code>atan2</code>, <code>cosh</code>, <code>sinh</code>, <code>tanh</code>, <code>pow</code>, |
|
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|
10064 <code>frexp</code>, and <code>ldexp</code>. |
|
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|
10065 You can replace <code>math.pow(x,y)</code> with <code>x^y</code>; |
|
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|
10066 you can replace <code>math.atan2</code> with <code>math.atan</code>, |
|
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|
10067 which now accepts one or two parameters; |
|
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|
10068 you can replace <code>math.ldexp(x,exp)</code> with <code>x * 2.0^exp</code>. |
|
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|
10069 For the other operations, |
|
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|
10070 you can either use an external library or |
|
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|
10071 implement them in Lua. |
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|
10072 </li> |
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|
10073 |
|
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|
10074 <li> |
|
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|
10075 The searcher for C loaders used by <a href="#pdf-require"><code>require</code></a> |
|
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|
10076 changed the way it handles versioned names. |
|
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|
10077 Now, the version should come after the module name |
|
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|
10078 (as is usual in most other tools). |
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10079 For compatibility, that searcher still tries the old format |
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|
10080 if it cannot find an open function according to the new style. |
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|
10081 (Lua 5.2 already worked that way, |
|
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|
10082 but it did not document the change.) |
|
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|
10083 </li> |
|
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|
10084 |
|
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|
10085 </ul> |
|
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|
10086 |
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|
10087 |
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|
10088 |
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10089 |
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|
10090 <h2>8.3 – <a name="8.3">Changes in the API</a></h2> |
|
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|
10091 |
|
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|
10092 |
|
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|
10093 <ul> |
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|
10094 |
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|
10095 <li> |
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|
10096 Continuation functions now receive as parameters what they needed |
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|
10097 to get through <code>lua_getctx</code>, |
|
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10098 so <code>lua_getctx</code> has been removed. |
|
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|
10099 Adapt your code accordingly. |
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|
10100 </li> |
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|
10101 |
|
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|
10102 <li> |
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|
10103 Function <a href="#lua_dump"><code>lua_dump</code></a> has an extra parameter, <code>strip</code>. |
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10104 Use 0 as the value of this parameter to get the old behavior. |
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|
10105 </li> |
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|
10106 |
|
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|
10107 <li> |
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|
10108 Functions to inject/project unsigned integers |
|
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|
10109 (<code>lua_pushunsigned</code>, <code>lua_tounsigned</code>, <code>lua_tounsignedx</code>, |
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|
10110 <code>luaL_checkunsigned</code>, <code>luaL_optunsigned</code>) |
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10111 were deprecated. |
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10112 Use their signed equivalents with a type cast. |
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10113 </li> |
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10114 |
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10115 <li> |
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10116 Macros to project non-default integer types |
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10117 (<code>luaL_checkint</code>, <code>luaL_optint</code>, <code>luaL_checklong</code>, <code>luaL_optlong</code>) |
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10118 were deprecated. |
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10119 Use their equivalent over <a href="#lua_Integer"><code>lua_Integer</code></a> with a type cast |
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10120 (or, when possible, use <a href="#lua_Integer"><code>lua_Integer</code></a> in your code). |
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10121 </li> |
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10122 |
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10123 </ul> |
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10124 |
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10125 |
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10126 |
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10127 |
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10128 <h1>9 – <a name="9">The Complete Syntax of Lua</a></h1> |
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10129 |
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10130 <p> |
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10131 Here is the complete syntax of Lua in extended BNF. |
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10132 As usual in extended BNF, |
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10133 {A} means 0 or more As, |
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10134 and [A] means an optional A. |
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10135 (For operator precedences, see <a href="#3.4.8">§3.4.8</a>; |
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10136 for a description of the terminals |
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10137 Name, Numeral, |
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10138 and LiteralString, see <a href="#3.1">§3.1</a>.) |
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10139 |
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10140 |
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10141 |
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10142 |
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10143 <pre> |
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10144 |
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10145 chunk ::= block |
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10146 |
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10147 block ::= {stat} [retstat] |
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10148 |
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10149 stat ::= ‘<b>;</b>’ | |
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10150 varlist ‘<b>=</b>’ explist | |
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10151 functioncall | |
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10152 label | |
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10153 <b>break</b> | |
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10154 <b>goto</b> Name | |
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10155 <b>do</b> block <b>end</b> | |
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10156 <b>while</b> exp <b>do</b> block <b>end</b> | |
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10157 <b>repeat</b> block <b>until</b> exp | |
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10158 <b>if</b> exp <b>then</b> block {<b>elseif</b> exp <b>then</b> block} [<b>else</b> block] <b>end</b> | |
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10159 <b>for</b> Name ‘<b>=</b>’ exp ‘<b>,</b>’ exp [‘<b>,</b>’ exp] <b>do</b> block <b>end</b> | |
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10160 <b>for</b> namelist <b>in</b> explist <b>do</b> block <b>end</b> | |
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10161 <b>function</b> funcname funcbody | |
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10162 <b>local</b> <b>function</b> Name funcbody | |
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10163 <b>local</b> namelist [‘<b>=</b>’ explist] |
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10164 |
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10165 retstat ::= <b>return</b> [explist] [‘<b>;</b>’] |
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10166 |
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10167 label ::= ‘<b>::</b>’ Name ‘<b>::</b>’ |
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10168 |
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10169 funcname ::= Name {‘<b>.</b>’ Name} [‘<b>:</b>’ Name] |
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10170 |
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10171 varlist ::= var {‘<b>,</b>’ var} |
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10172 |
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10173 var ::= Name | prefixexp ‘<b>[</b>’ exp ‘<b>]</b>’ | prefixexp ‘<b>.</b>’ Name |
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10174 |
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10175 namelist ::= Name {‘<b>,</b>’ Name} |
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10176 |
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10177 explist ::= exp {‘<b>,</b>’ exp} |
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10178 |
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10179 exp ::= <b>nil</b> | <b>false</b> | <b>true</b> | Numeral | LiteralString | ‘<b>...</b>’ | functiondef | |
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10180 prefixexp | tableconstructor | exp binop exp | unop exp |
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10181 |
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10182 prefixexp ::= var | functioncall | ‘<b>(</b>’ exp ‘<b>)</b>’ |
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10183 |
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10184 functioncall ::= prefixexp args | prefixexp ‘<b>:</b>’ Name args |
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10185 |
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10186 args ::= ‘<b>(</b>’ [explist] ‘<b>)</b>’ | tableconstructor | LiteralString |
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10187 |
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10188 functiondef ::= <b>function</b> funcbody |
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10189 |
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10190 funcbody ::= ‘<b>(</b>’ [parlist] ‘<b>)</b>’ block <b>end</b> |
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10191 |
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10192 parlist ::= namelist [‘<b>,</b>’ ‘<b>...</b>’] | ‘<b>...</b>’ |
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10193 |
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10194 tableconstructor ::= ‘<b>{</b>’ [fieldlist] ‘<b>}</b>’ |
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10195 |
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10196 fieldlist ::= field {fieldsep field} [fieldsep] |
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10197 |
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10198 field ::= ‘<b>[</b>’ exp ‘<b>]</b>’ ‘<b>=</b>’ exp | Name ‘<b>=</b>’ exp | exp |
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10199 |
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10200 fieldsep ::= ‘<b>,</b>’ | ‘<b>;</b>’ |
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10201 |
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10202 binop ::= ‘<b>+</b>’ | ‘<b>-</b>’ | ‘<b>*</b>’ | ‘<b>/</b>’ | ‘<b>//</b>’ | ‘<b>^</b>’ | ‘<b>%</b>’ | |
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10203 ‘<b>&</b>’ | ‘<b>~</b>’ | ‘<b>|</b>’ | ‘<b>>></b>’ | ‘<b><<</b>’ | ‘<b>..</b>’ | |
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10204 ‘<b><</b>’ | ‘<b><=</b>’ | ‘<b>></b>’ | ‘<b>>=</b>’ | ‘<b>==</b>’ | ‘<b>~=</b>’ | |
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10205 <b>and</b> | <b>or</b> |
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10206 |
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10207 unop ::= ‘<b>-</b>’ | <b>not</b> | ‘<b>#</b>’ | ‘<b>~</b>’ |
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10208 |
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10209 </pre> |
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10210 |
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10211 <p> |
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10212 |
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10213 |
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10214 |
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10215 |
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10216 |
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10217 |
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10218 |
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10219 |
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10220 <HR> |
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10221 <SMALL CLASS="footer"> |
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10222 Last update: |
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10223 Fri Jan 16 00:58:20 BRST 2015 |
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parents:
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10224 </SMALL> |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
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10225 <!-- |
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e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
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10226 Last change: minor edit |
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e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
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10227 --> |
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e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
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10228 |
| 372 | 10229 </div> |
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386
db23f654f87d
make all of website use luan
Franklin Schmidt <fschmidt@gmail.com>
parents:
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10230 |
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391
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replace Html.simply_html_page with simply_html_head and simply_html_body_bottom
Franklin Schmidt <fschmidt@gmail.com>
parents:
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10231 <% Html.simply_html_body_bottom() %> |
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2f5cc9c2cbf0
replace Html.simply_html_page with simply_html_head and simply_html_body_bottom
Franklin Schmidt <fschmidt@gmail.com>
parents:
389
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10232 </body> |
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2f5cc9c2cbf0
replace Html.simply_html_page with simply_html_head and simply_html_body_bottom
Franklin Schmidt <fschmidt@gmail.com>
parents:
389
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10233 </html> |
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2f5cc9c2cbf0
replace Html.simply_html_page with simply_html_head and simply_html_body_bottom
Franklin Schmidt <fschmidt@gmail.com>
parents:
389
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10234 <% |
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db23f654f87d
make all of website use luan
Franklin Schmidt <fschmidt@gmail.com>
parents:
382
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10235 end |