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7 <title>Luan Reference Manual</title> | |
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17 <body> |
372 | 18 <div container> |
19 <div><small><a href="/">Luan</a></small></div> | |
20 | |
21 <h1>Luan Reference Manual</h1> | |
22 | |
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23 <p> |
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24 <small> |
372 | 25 Original copyright © 2015 Lua.org, PUC-Rio. |
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26 Freely available under the terms of the |
372 | 27 <a href="http://www.lua.org/license.html">Lua license</a>. |
28 Modified for Luan. | |
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29 </small> |
372 | 30 </p> |
31 | |
32 <hr/> | |
33 | |
34 <h2>Contents</h2> | |
35 | |
36 <div margin-bottom="1em"><a href="#intro">Introduction</a></div> | |
37 | |
373 | 38 <div margin-bottom="1em"> |
39 <a href="#basic">Basic Concepts</a> | |
40 <ul> | |
41 <li><a href="#types">Values and Types</a></li> | |
42 <li><a href="#env">Environments</a></li> | |
43 <li><a href="#error">Error Handling</a></li> | |
44 <li><a href="#meta">Metatables and Metamethods</a></li> | |
380 | 45 <li><a href="#gc">Garbage Collection</a></li> |
46 </ul> | |
47 </div> | |
48 | |
49 <div margin-bottom="1em"> | |
50 <a href="#lang">The Language</a> | |
51 <ul> | |
52 <li><a href="#lex">Lexical Conventions</a></li> | |
53 <li><a href="#vars">Variables</a></li> | |
373 | 54 </ul> |
55 </div> | |
56 | |
372 | 57 <hr/> |
58 | |
373 | 59 |
372 | 60 <h2 margin-top="1em"><a name="intro">Introduction</a></h2> |
61 | |
62 <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> | |
63 | |
64 <p>Luan is implemented in Java and is tightly coupled with Java. So it makes a great scripting language for Java programmers.</p> | |
65 | |
66 <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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67 |
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68 |
373 | 69 <h2 margin-top="1em"><a name="basic">Basic Concepts</a></h2> |
70 | |
71 <p>This section describes the basic concepts of the language.</p> | |
72 | |
73 <h3 margin-top="1em"><a name="types">Values and Types</a></h3> | |
74 | |
75 <p> | |
76 Luan is a <i>dynamically typed language</i>. | |
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77 This means that |
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78 variables do not have types; only values do. |
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79 There are no type definitions in the language. |
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80 All values carry their own type. |
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81 |
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82 |
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83 <p> |
373 | 84 All values in Luan are <i>first-class values</i>. |
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85 This means that all values can be stored in variables, |
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86 passed as arguments to other functions, and returned as results. |
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87 |
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88 |
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89 <p> |
373 | 90 There are eight basic types in Luan: |
91 <i>nil</i>, <i>boolean</i>, <i>number</i>, | |
92 <i>string</i>, <i>binary</i>, <i>function</i>, <i>userdata</i>, | |
93 and <i>table</i>. | |
94 <i>Nil</i> is the type of the value <b>nil</b>, | |
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95 whose main property is to be different from any other value; |
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96 it usually represents the absence of a useful value. |
373 | 97 <i>Nil</i> is implemented as the Java value <i>null</i>. |
98 <i>Boolean</i> is the type of the values <b>false</b> and <b>true</b>. | |
99 <i>Boolean</i> is implemented as the Java class <i>Boolean</i>. | |
100 <i>Number</i> represents both | |
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101 integer numbers and real (floating-point) numbers. |
373 | 102 <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 |
103 the underlying Java implementation. | |
104 | |
105 <i>String</i> is implemented as the Java class <i>String</i>. | |
106 <i>Binary</i> is implemented as the Java type <i>byte[]</i>. | |
107 | |
108 | |
109 <p> | |
110 Luan can call (and manipulate) functions written in Luan and | |
111 functions written in Java (see <a href="#3.4.10">§3.4.10</a>). | |
112 Both are represented by the type <i>function</i>. | |
113 | |
114 | |
115 <p> | |
116 The type <i>userdata</i> is provided to allow arbitrary Java objects to | |
117 be stored in Luan variables. | |
118 A userdata value is a Java object that isn't one of the standard Luan types. | |
119 Userdata has no predefined operations in Luan, | |
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120 except assignment and identity test. |
373 | 121 Userdata is useful then Java access is enabled in Luan |
122 | |
123 | |
124 | |
125 <p> | |
126 The type <i>table</i> implements associative arrays, | |
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127 that is, arrays that can be indexed not only with numbers, |
373 | 128 but with any Luan value except <b>nil</b>. |
129 Tables can be <i>heterogeneous</i>; | |
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130 that is, they can contain values of all types (except <b>nil</b>). |
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131 Any key with value <b>nil</b> is not considered part of the table. |
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132 Conversely, any key that is not part of a table has |
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133 an associated value <b>nil</b>. |
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134 |
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135 |
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136 <p> |
373 | 137 Tables are the sole data-structuring mechanism in Luan; |
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138 they can be used to represent ordinary arrays, sequences, |
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139 symbol tables, sets, records, graphs, trees, etc. |
373 | 140 To represent records, Luan uses the field name as an index. |
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141 The language supports this representation by |
373 | 142 providing <tt>a.name</tt> as syntactic sugar for <tt>a["name"]</tt>. |
143 There are several convenient ways to create tables in Luan | |
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144 (see <a href="#3.4.9">§3.4.9</a>). |
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145 |
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146 |
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147 <p> |
373 | 148 We use the term <i>sequence</i> to denote a table where |
149 the set of all positive numeric keys is equal to {1..<i>n</i>} | |
150 for some non-negative integer <i>n</i>, | |
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151 which is called the length of the sequence (see <a href="#3.4.7">§3.4.7</a>). |
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152 |
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153 |
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154 <p> |
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155 Like indices, |
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156 the values of table fields can be of any type. |
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157 In particular, |
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158 because functions are first-class values, |
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159 table fields can contain functions. |
373 | 160 Thus tables can also carry <i>methods</i> (see <a href="#3.4.11">§3.4.11</a>). |
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161 |
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162 |
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163 <p> |
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164 The indexing of tables follows |
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165 the definition of raw equality in the language. |
373 | 166 The expressions <tt>a[i]</tt> and <tt>a[j]</tt> |
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167 denote the same table element |
373 | 168 if and only if <tt>i</tt> and <tt>j</tt> are raw equal |
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169 (that is, equal without metamethods). |
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170 In particular, floats with integral values |
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171 are equal to their respective integers |
373 | 172 (e.g., <tt>1.0 == 1</tt>). |
173 | |
174 | |
175 <p> | |
176 Luan values are <i>objects</i>: | |
177 variables do not actually <i>contain</i> values, | |
178 only <i>references</i> to them. | |
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179 Assignment, parameter passing, and function returns |
373 | 180 always manipulate references to values; |
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181 these operations do not imply any kind of copy. |
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182 |
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183 |
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184 <p> |
373 | 185 The library function <a href="#pdf-type"><tt>Luan.type</tt></a> returns a string describing the type |
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186 of a given value (see <a href="#6.1">§6.1</a>). |
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187 |
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188 |
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189 |
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190 |
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191 |
373 | 192 <h3 margin-top="1em"><a name="env">Environments</a></h3> |
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193 |
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194 <p> |
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195 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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196 any reference to a free name |
373 | 197 (that is, a name not bound to any declaration) <tt>var</tt> |
198 is syntactically translated to <tt>_ENV.var</tt>. | |
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199 Moreover, every chunk is compiled in the scope of |
373 | 200 an external local variable named <tt>_ENV</tt> (see <a href="#3.3.2">§3.3.2</a>), |
201 so <tt>_ENV</tt> itself is never a free name in a chunk. | |
202 | |
203 | |
204 <p> | |
205 Despite the existence of this external <tt>_ENV</tt> variable and | |
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206 the translation of free names, |
373 | 207 <tt>_ENV</tt> is a completely regular name. |
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208 In particular, |
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209 you can define new variables and parameters with that name. |
373 | 210 Each reference to a free name uses the <tt>_ENV</tt> that is |
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211 visible at that point in the program, |
373 | 212 following the usual visibility rules of Luan (see <a href="#3.5">§3.5</a>). |
213 | |
214 | |
215 <p> | |
216 Any table used as the value of <tt>_ENV</tt> is called an <i>environment</i>. | |
217 | |
218 | |
219 <p> | |
220 When Luan loads a chunk, | |
221 the default value for its <tt>_ENV</tt> is an empty table. | |
222 | |
223 <p> | |
224 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. | |
225 | |
226 | |
227 | |
228 | |
229 <h3 margin-top="1em"><a name="error">Error Handling</a></h3> | |
230 | |
231 <p> | |
232 Luan code can explicitly generate an error by calling the | |
233 <a href="#pdf-error"><tt>error</tt></a> function. | |
234 If you need to catch errors in Luan, | |
235 you can use <a href="#pdf-pcall"><tt>pcall</tt></a> or <a href="#pdf-xpcall"><tt>try</tt></a> | |
236 to call a given function in <i>protected mode</i>. | |
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237 |
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238 |
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239 <p> |
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240 Whenever there is an error, |
373 | 241 an <i>error object</i> (also called an <i>error message</i>) |
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242 is propagated with information about the error. |
373 | 243 Luan itself only generates errors whose error object is a string, |
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244 but programs may generate errors with |
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245 any value as the error object. |
373 | 246 It is up to the Luan program or its host to handle such error objects. |
247 | |
248 | |
249 | |
250 | |
251 | |
252 <h3 margin-top="1em"><a name="meta">Metatables and Metamethods</a></h3> | |
253 | |
254 <p> | |
255 Every table in Luan can have a <i>metatable</i>. | |
256 This <i>metatable</i> is an ordinary Luan table | |
371
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257 that defines the behavior of the original value |
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258 under certain special operations. |
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259 You can change several aspects of the behavior |
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260 of operations over a value by setting specific fields in its metatable. |
373 | 261 For instance, when a table is the operand of an addition, |
262 Luan checks for a function in the field "<tt>__add</tt>" of the table's metatable. | |
371
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263 If it finds one, |
373 | 264 Luan calls this function to perform the addition. |
265 | |
266 | |
267 <p> | |
268 The keys in a metatable are derived from the <i>event</i> names; | |
269 the corresponding values are called <ii>metamethods</i>. | |
270 In the previous example, the event is <tt>"add"</tt> | |
371
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271 and the metamethod is the function that performs the addition. |
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272 |
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273 |
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274 <p> |
373 | 275 You can query the metatable of any table |
276 using the <a href="#pdf-getmetatable"><tt>get_metatable</tt></a> function. | |
371
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277 |
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278 |
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279 <p> |
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280 You can replace the metatable of tables |
373 | 281 using the <a href="#pdf-setmetatable"><tt>set_metatable</tt></a> function. |
282 | |
283 | |
284 <p> | |
285 A metatable controls how a table behaves in | |
371
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286 arithmetic operations, bitwise operations, |
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287 order comparisons, concatenation, length operation, calls, and indexing. |
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288 |
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289 |
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290 <p> |
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291 A detailed list of events controlled by metatables is given next. |
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292 Each operation is identified by its corresponding event name. |
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293 The key for each event is a string with its name prefixed by |
373 | 294 two underscores, '<tt>__</tt>'; |
371
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295 for instance, the key for operation "add" is the |
373 | 296 string "<tt>__add</tt>". |
371
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297 Note that queries for metamethods are always raw; |
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298 the access to a metamethod does not invoke other metamethods. |
373 | 299 You can emulate how Luan queries a metamethod for an object <tt>obj</tt> |
371
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300 with the following code: |
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301 |
382 | 302 <p><tt><pre> |
373 | 303 raw_get(get_metatable(obj) or {}, "__" .. event_name) |
382 | 304 </pre></tt></p> |
373 | 305 |
306 <p> | |
307 Here are the events: | |
371
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308 |
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309 <ul> |
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310 |
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311 <li><b>"add": </b> |
373 | 312 the <tt>+</tt> operation. |
313 | |
314 If any operand for an addition is a table, | |
315 Luan will try to call a metamethod. | |
316 First, Luan will check the first operand (even if it is valid). | |
317 If that operand does not define a metamethod for the "<tt>__add</tt>" event, | |
318 then Luan will check the second operand. | |
319 If Luan can find a metamethod, | |
371
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320 it calls the metamethod with the two operands as arguments, |
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321 and the result of the call |
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322 (adjusted to one value) |
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323 is the result of the operation. |
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324 Otherwise, |
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325 it raises an error. |
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326 </li> |
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327 |
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328 <li><b>"sub": </b> |
373 | 329 the <tt>-</tt> operation. |
371
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330 |
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331 Behavior similar to the "add" operation. |
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332 </li> |
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333 |
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334 <li><b>"mul": </b> |
373 | 335 the <tt>*</tt> operation. |
371
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336 |
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337 Behavior similar to the "add" operation. |
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338 </li> |
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339 |
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340 <li><b>"div": </b> |
373 | 341 the <tt>/</tt> operation. |
371
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342 |
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343 Behavior similar to the "add" operation. |
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344 </li> |
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345 |
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346 <li><b>"mod": </b> |
373 | 347 the <tt>%</tt> operation. |
371
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348 |
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349 Behavior similar to the "add" operation. |
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350 </li> |
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351 |
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352 <li><b>"pow": </b> |
373 | 353 the <tt>^</tt> (exponentiation) operation. |
371
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354 |
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355 Behavior similar to the "add" operation. |
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356 </li> |
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357 |
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358 <li><b>"unm": </b> |
373 | 359 the <tt>-</tt> (unary minus) operation. |
371
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360 |
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361 Behavior similar to the "add" operation. |
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362 </li> |
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363 |
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364 <li><b>"concat": </b> |
373 | 365 the <tt>..</tt> (concatenation) operation. |
366 | |
367 Behavior similar to the "add" operation. | |
371
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368 </li> |
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369 |
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370 <li><b>"len": </b> |
373 | 371 the <tt>#</tt> (length) operation. |
372 | |
371
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373 If there is a metamethod, |
373 | 374 Luan calls it with the object as argument, |
371
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375 and the result of the call |
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376 (always adjusted to one value) |
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377 is the result of the operation. |
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378 If there is no metamethod but the object is a table, |
373 | 379 then Luan uses the table length operation (see <a href="#3.4.7">§3.4.7</a>). |
380 Otherwise, Luan raises an error. | |
371
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381 </li> |
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382 |
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383 <li><b>"eq": </b> |
373 | 384 the <tt>==</tt> (equal) operation. |
371
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385 |
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386 Behavior similar to the "add" operation, |
373 | 387 except that Luan will try a metamethod only when the values |
388 being compared are both tables | |
371
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389 and they are not primitively equal. |
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390 The result of the call is always converted to a boolean. |
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391 </li> |
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392 |
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393 <li><b>"lt": </b> |
373 | 394 the <tt><</tt> (less than) operation. |
395 | |
396 Behavior similar to the "add" operation. | |
371
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397 The result of the call is always converted to a boolean. |
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398 </li> |
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399 |
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400 <li><b>"le": </b> |
373 | 401 the <tt><=</tt> (less equal) operation. |
371
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402 |
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403 Unlike other operations, |
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404 The less-equal operation can use two different events. |
373 | 405 First, Luan looks for the "<tt>__le</tt>" metamethod in both operands, |
371
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406 like in the "lt" operation. |
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407 If it cannot find such a metamethod, |
373 | 408 then it will try the "<tt>__lt</tt>" event, |
409 assuming that <tt>a <= b</tt> is equivalent to <tt>not (b < a)</tt>. | |
371
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410 As with the other comparison operators, |
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411 the result is always a boolean. |
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412 </li> |
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413 |
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414 <li><b>"index": </b> |
373 | 415 The indexing access <tt>table[key]</tt>. |
416 | |
417 This event happens | |
418 when <tt>key</tt> is not present in <tt>table</tt>. | |
419 The metamethod is looked up in <tt>table</tt>. | |
371
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420 |
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421 |
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422 <p> |
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423 Despite the name, |
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424 the metamethod for this event can be either a function or a table. |
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425 If it is a function, |
373 | 426 it is called with <tt>table</tt> and <tt>key</tt> as arguments. |
371
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427 If it is a table, |
373 | 428 the final result is the result of indexing this table with <tt>key</tt>. |
371
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429 (This indexing is regular, not raw, |
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430 and therefore can trigger another metamethod.) |
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431 </li> |
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432 |
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433 <li><b>"newindex": </b> |
373 | 434 The indexing assignment <tt>table[key] = value</tt>. |
371
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435 |
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436 Like the index event, |
373 | 437 this event happens when |
438 when <tt>key</tt> is not present in <tt>table</tt>. | |
439 The metamethod is looked up in <tt>table</tt>. | |
371
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440 |
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441 |
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442 <p> |
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443 Like with indexing, |
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444 the metamethod for this event can be either a function or a table. |
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445 If it is a function, |
373 | 446 it is called with <tt>table</tt>, <tt>key</tt>, and <tt>value</tt> as arguments. |
371
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447 If it is a table, |
373 | 448 Luan does an indexing assignment to this table with the same key and value. |
371
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449 (This assignment is regular, not raw, |
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450 and therefore can trigger another metamethod.) |
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451 |
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452 |
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453 <p> |
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454 Whenever there is a "newindex" metamethod, |
373 | 455 Luan does not perform the primitive assignment. |
371
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456 (If necessary, |
373 | 457 the metamethod itself can call <a href="#pdf-rawset"><tt>raw_set</tt></a> |
371
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458 to do the assignment.) |
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459 </li> |
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460 |
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461 <li><b>"call": </b> |
373 | 462 The call operation <tt>func(args)</tt>. |
463 | |
464 This event happens when Luan tries to call a table. | |
465 The metamethod is looked up in <tt>func</tt>. | |
371
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466 If present, |
373 | 467 the metamethod is called with <tt>func</tt> as its first argument, |
468 followed by the arguments of the original call (<tt>args</tt>). | |
371
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469 </li> |
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470 |
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471 </ul> |
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472 |
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473 |
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474 |
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475 |
380 | 476 <h3 margin-top="1em"><a name="gc">Garbage Collection</a></h3> |
477 | |
478 <p> | |
479 Luan uses Java's garbage collection. | |
480 | |
481 | |
482 | |
483 | |
484 | |
485 <h2 margin-top="1em"><a name="lang">The Language</a></h2> | |
486 | |
487 <p> | |
488 This section describes the lexis, the syntax, and the semantics of Luan. | |
371
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489 In other words, |
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490 this section describes |
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491 which tokens are valid, |
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492 how they can be combined, |
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493 and what their combinations mean. |
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494 |
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495 |
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496 <p> |
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497 Language constructs will be explained using the usual extended BNF notation, |
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498 in which |
380 | 499 {<i>a</i>} means 0 or more <i>a</i>'s, and |
500 [<i>a</i>] means an optional <i>a</i>. | |
371
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501 Non-terminals are shown like non-terminal, |
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502 keywords are shown like <b>kword</b>, |
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503 and other terminal symbols are shown like ‘<b>=</b>’. |
380 | 504 The complete syntax of Luan can be found in <a href="#9">§9</a> |
371
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505 at the end of this manual. |
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506 |
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507 |
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508 |
380 | 509 <h3 margin-top="1em"><a name="lex">Lexical Conventions</a></h3> |
510 | |
511 <p> | |
512 Luan ignores spaces and comments | |
371
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513 between lexical elements (tokens), |
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514 except as delimiters between names and keywords. |
380 | 515 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. |
516 | |
517 <p> | |
518 <i>Names</i> | |
519 (also called <i>identifiers</i>) | |
520 in Luan can be any string of letters, | |
371
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521 digits, and underscores, |
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522 not beginning with a digit. |
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523 Identifiers are used to name variables, table fields, and labels. |
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524 |
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525 |
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526 <p> |
380 | 527 The following <i>keywords</i> are reserved |
371
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528 and cannot be used as names: |
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529 |
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530 |
382 | 531 <p><pre> |
371
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532 and break do else elseif end |
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533 false for function goto if in |
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534 local nil not or repeat return |
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535 then true until while |
382 | 536 </pre></p> |
371
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537 |
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538 <p> |
380 | 539 Luan is a case-sensitive language: |
540 <tt>and</tt> is a reserved word, but <tt>And</tt> and <tt>AND</tt> | |
371
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541 are two different, valid names. |
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542 |
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543 |
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544 <p> |
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545 The following strings denote other tokens: |
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546 |
382 | 547 <p><pre> |
371
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548 + - * / % ^ # |
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549 & ~ | << >> // |
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550 == ~= <= >= < > = |
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551 ( ) { } [ ] :: |
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552 ; : , . .. ... |
382 | 553 </pre></p> |
371
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554 |
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555 <p> |
380 | 556 <i>Literal strings</i> |
371
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557 can be delimited by matching single or double quotes, |
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558 and can contain the following C-like escape sequences: |
380 | 559 '<tt>\a</tt>' (bell), |
560 '<tt>\b</tt>' (backspace), | |
561 '<tt>\f</tt>' (form feed), | |
562 '<tt>\n</tt>' (newline), | |
563 '<tt>\r</tt>' (carriage return), | |
564 '<tt>\t</tt>' (horizontal tab), | |
565 '<tt>\v</tt>' (vertical tab), | |
566 '<tt>\\</tt>' (backslash), | |
567 '<tt>\"</tt>' (quotation mark [double quote]), | |
568 and '<tt>\'</tt>' (apostrophe [single quote]). | |
371
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569 A backslash followed by a real newline |
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570 results in a newline in the string. |
380 | 571 The escape sequence '<tt>\z</tt>' skips the following span |
371
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572 of white-space characters, |
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573 including line breaks; |
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574 it is particularly useful to break and indent a long literal string |
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575 into multiple lines without adding the newlines and spaces |
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576 into the string contents. |
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577 |
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578 |
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579 <p> |
380 | 580 Luan can specify any character in a literal string by its numerical value. |
371
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581 This can be done |
380 | 582 with the escape sequence <tt>\x<i>XX</i></tt>, |
583 where <i>XX</i> is a sequence of exactly two hexadecimal digits, | |
584 or with the escape sequence <tt>\<i>ddd</i></tt>, | |
585 where <i>ddd</i> is a sequence of up to three decimal digits. | |
371
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586 (Note that if a decimal escape sequence is to be followed by a digit, |
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587 it must be expressed using exactly three digits.) |
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588 |
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589 |
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590 <p> |
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591 Literal strings can also be defined using a long format |
380 | 592 enclosed by <i>long brackets</i>. |
593 We define an <i>opening long bracket of level <i>n</i></i> as an opening | |
594 square bracket followed by <i>n</i> equal signs followed by another | |
371
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595 opening square bracket. |
380 | 596 So, an opening long bracket of level 0 is written as <tt>[[</tt>, |
597 an opening long bracket of level 1 is written as <tt>[=[</tt>, | |
371
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598 and so on. |
380 | 599 A <i>closing long bracket</i> is defined similarly; |
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600 for instance, |
380 | 601 a closing long bracket of level 4 is written as <tt>]====]</tt>. |
602 A <i>long literal</i> starts with an opening long bracket of any level and | |
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603 ends at the first closing long bracket of the same level. |
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604 It can contain any text except a closing bracket of the same level. |
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605 Literals in this bracketed form can run for several lines, |
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606 do not interpret any escape sequences, |
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607 and ignore long brackets of any other level. |
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608 Any kind of end-of-line sequence |
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609 (carriage return, newline, carriage return followed by newline, |
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610 or newline followed by carriage return) |
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611 is converted to a simple newline. |
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612 |
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613 |
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614 <p> |
380 | 615 Any character in a literal string not |
371
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616 explicitly affected by the previous rules represents itself. |
380 | 617 However, Luan opens files for parsing in text mode, |
371
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618 and the system file functions may have problems with |
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619 some control characters. |
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620 So, it is safer to represent |
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621 non-text data as a quoted literal with |
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622 explicit escape sequences for non-text characters. |
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623 |
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624 |
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625 <p> |
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626 For convenience, |
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627 when the opening long bracket is immediately followed by a newline, |
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628 the newline is not included in the string. |
380 | 629 As an example |
371
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630 the five literal strings below denote the same string: |
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631 |
382 | 632 <p><pre> |
371
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633 a = 'alo\n123"' |
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634 a = "alo\n123\"" |
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635 a = '\97lo\10\04923"' |
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636 a = [[alo |
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637 123"]] |
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638 a = [==[ |
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639 alo |
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640 123"]==] |
382 | 641 </pre></p> |
371
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642 |
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643 <p> |
380 | 644 A <i>numerical constant</i> (or <i>numeral</i>) |
371
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645 can be written with an optional fractional part |
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646 and an optional decimal exponent, |
380 | 647 marked by a letter '<tt>e</tt>' or '<tt>E</tt>'. |
648 Luan also accepts hexadecimal constants, | |
649 which start with <tt>0x</tt> or <tt>0X</tt>. | |
371
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650 Hexadecimal constants also accept an optional fractional part |
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651 plus an optional binary exponent, |
380 | 652 marked by a letter '<tt>p</tt>' or '<tt>P</tt>'. |
371
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653 A numeric constant with a fractional dot or an exponent |
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654 denotes a float; |
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655 otherwise it denotes an integer. |
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656 Examples of valid integer constants are |
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657 |
382 | 658 <p><pre> |
371
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659 3 345 0xff 0xBEBADA |
382 | 660 </pre></p> |
661 | |
662 <p> | |
371
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663 Examples of valid float constants are |
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664 |
382 | 665 <p><pre> |
371
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666 3.0 3.1416 314.16e-2 0.31416E1 34e1 |
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667 0x0.1E 0xA23p-4 0X1.921FB54442D18P+1 |
382 | 668 </pre></p> |
371
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669 |
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670 <p> |
380 | 671 A <i>comment</i> starts with a double hyphen (<tt>--</tt>) |
371
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672 anywhere outside a string. |
380 | 673 If the text immediately after <tt>--</tt> is not an opening long bracket, |
674 the comment is a <i>short comment</i>, | |
371
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675 which runs until the end of the line. |
380 | 676 Otherwise, it is a <i>long comment</i>, |
371
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677 which runs until the corresponding closing long bracket. |
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678 Long comments are frequently used to disable code temporarily. |
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679 |
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680 |
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681 |
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682 |
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683 |
380 | 684 <h3 margin-top="1em"><a name="vars">Variables</a></h3> |
371
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685 |
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686 <p> |
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687 Variables are places that store values. |
380 | 688 There are three kinds of variables in Luan: |
371
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689 global variables, local variables, and table fields. |
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690 |
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691 |
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692 <p> |
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693 A single name can denote a global variable or a local variable |
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694 (or a function's formal parameter, |
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695 which is a particular kind of local variable): |
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696 |
382 | 697 <p><pre> |
371
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698 var ::= Name |
382 | 699 </pre></p> |
700 | |
701 <p> | |
371
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702 Name denotes identifiers, as defined in <a href="#3.1">§3.1</a>. |
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703 |
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704 |
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705 <p> |
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706 Any variable name is assumed to be global unless explicitly declared |
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707 as a local (see <a href="#3.3.7">§3.3.7</a>). |
380 | 708 Local variables are <i>lexically scoped</i>: |
371
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709 local variables can be freely accessed by functions |
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710 defined inside their scope (see <a href="#3.5">§3.5</a>). |
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711 |
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712 |
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713 <p> |
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714 Before the first assignment to a variable, its value is <b>nil</b>. |
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715 |
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716 |
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717 <p> |
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718 Square brackets are used to index a table: |
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719 |
382 | 720 <p><pre> |
371
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721 var ::= prefixexp ‘<b>[</b>’ exp ‘<b>]</b>’ |
382 | 722 </pre></p> |
723 | |
724 <p> | |
371
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725 The meaning of accesses to table fields can be changed via metatables. |
380 | 726 An access to an indexed variable <tt>t[i]</tt> is equivalent to |
727 a call <tt>gettable_event(t,i)</tt>. | |
371
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728 (See <a href="#2.4">§2.4</a> for a complete description of the |
380 | 729 <tt>gettable_event</tt> function. |
730 This function is not defined or callable in Luan. | |
371
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731 We use it here only for explanatory purposes.) |
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732 |
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733 |
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734 <p> |
380 | 735 The syntax <tt>var.Name</tt> is just syntactic sugar for |
736 <tt>var["Name"]</tt>: | |
371
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737 |
382 | 738 <p><pre> |
371
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739 var ::= prefixexp ‘<b>.</b>’ Name |
382 | 740 </pre></p> |
371
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741 |
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742 <p> |
380 | 743 An access to a global variable <tt>x</tt> |
744 is equivalent to <tt>_ENV.x</tt>. | |
371
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745 Due to the way that chunks are compiled, |
380 | 746 <tt>_ENV</tt> is never a global name (see <a href="#2.2">§2.2</a>). |
371
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747 |
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748 |
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749 |
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750 |
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751 |
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752 <h2>3.3 – <a name="3.3">Statements</a></h2> |
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753 |
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754 <p> |
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755 Lua supports an almost conventional set of statements, |
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756 similar to those in Pascal or C. |
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757 This set includes |
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758 assignments, control structures, function calls, |
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759 and variable declarations. |
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760 |
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761 |
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762 |
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763 <h3>3.3.1 – <a name="3.3.1">Blocks</a></h3> |
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764 |
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765 <p> |
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766 A block is a list of statements, |
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767 which are executed sequentially: |
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768 |
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769 <pre> |
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770 block ::= {stat} |
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771 </pre><p> |
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772 Lua has <em>empty statements</em> |
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773 that allow you to separate statements with semicolons, |
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774 start a block with a semicolon |
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775 or write two semicolons in sequence: |
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776 |
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777 <pre> |
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778 stat ::= ‘<b>;</b>’ |
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779 </pre> |
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780 |
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781 <p> |
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782 Function calls and assignments |
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783 can start with an open parenthesis. |
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784 This possibility leads to an ambiguity in Lua's grammar. |
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785 Consider the following fragment: |
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786 |
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787 <pre> |
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788 a = b + c |
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789 (print or io.write)('done') |
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790 </pre><p> |
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791 The grammar could see it in two ways: |
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792 |
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793 <pre> |
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794 a = b + c(print or io.write)('done') |
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795 |
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796 a = b + c; (print or io.write)('done') |
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797 </pre><p> |
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798 The current parser always sees such constructions |
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799 in the first way, |
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800 interpreting the open parenthesis |
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801 as the start of the arguments to a call. |
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802 To avoid this ambiguity, |
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803 it is a good practice to always precede with a semicolon |
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804 statements that start with a parenthesis: |
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805 |
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806 <pre> |
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807 ;(print or io.write)('done') |
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808 </pre> |
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809 |
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810 <p> |
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811 A block can be explicitly delimited to produce a single statement: |
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812 |
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813 <pre> |
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814 stat ::= <b>do</b> block <b>end</b> |
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815 </pre><p> |
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816 Explicit blocks are useful |
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817 to control the scope of variable declarations. |
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818 Explicit blocks are also sometimes used to |
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819 add a <b>return</b> statement in the middle |
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820 of another block (see <a href="#3.3.4">§3.3.4</a>). |
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821 |
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822 |
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823 |
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824 |
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825 |
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826 <h3>3.3.2 – <a name="3.3.2">Chunks</a></h3> |
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827 |
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828 <p> |
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829 The unit of compilation of Lua is called a <em>chunk</em>. |
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830 Syntactically, |
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831 a chunk is simply a block: |
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832 |
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833 <pre> |
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834 chunk ::= block |
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835 </pre> |
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836 |
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837 <p> |
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838 Lua handles a chunk as the body of an anonymous function |
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839 with a variable number of arguments |
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840 (see <a href="#3.4.11">§3.4.11</a>). |
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841 As such, chunks can define local variables, |
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842 receive arguments, and return values. |
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843 Moreover, such anonymous function is compiled as in the |
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844 scope of an external local variable called <code>_ENV</code> (see <a href="#2.2">§2.2</a>). |
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845 The resulting function always has <code>_ENV</code> as its only upvalue, |
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846 even if it does not use that variable. |
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847 |
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848 |
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849 <p> |
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850 A chunk can be stored in a file or in a string inside the host program. |
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851 To execute a chunk, |
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852 Lua first <em>loads</em> it, |
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853 precompiling the chunk's code into instructions for a virtual machine, |
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854 and then Lua executes the compiled code |
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855 with an interpreter for the virtual machine. |
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856 |
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857 |
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858 <p> |
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859 Chunks can also be precompiled into binary form; |
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860 see program <code>luac</code> and function <a href="#pdf-string.dump"><code>string.dump</code></a> for details. |
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861 Programs in source and compiled forms are interchangeable; |
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862 Lua automatically detects the file type and acts accordingly (see <a href="#pdf-load"><code>load</code></a>). |
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863 |
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864 |
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865 |
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866 |
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867 |
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868 <h3>3.3.3 – <a name="3.3.3">Assignment</a></h3> |
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869 |
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870 <p> |
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871 Lua allows multiple assignments. |
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872 Therefore, the syntax for assignment |
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873 defines a list of variables on the left side |
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874 and a list of expressions on the right side. |
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875 The elements in both lists are separated by commas: |
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876 |
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877 <pre> |
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878 stat ::= varlist ‘<b>=</b>’ explist |
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879 varlist ::= var {‘<b>,</b>’ var} |
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880 explist ::= exp {‘<b>,</b>’ exp} |
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881 </pre><p> |
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882 Expressions are discussed in <a href="#3.4">§3.4</a>. |
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883 |
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884 |
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885 <p> |
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886 Before the assignment, |
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887 the list of values is <em>adjusted</em> to the length of |
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888 the list of variables. |
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889 If there are more values than needed, |
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890 the excess values are thrown away. |
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891 If there are fewer values than needed, |
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892 the list is extended with as many <b>nil</b>'s as needed. |
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893 If the list of expressions ends with a function call, |
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894 then all values returned by that call enter the list of values, |
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895 before the adjustment |
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896 (except when the call is enclosed in parentheses; see <a href="#3.4">§3.4</a>). |
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897 |
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898 |
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899 <p> |
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900 The assignment statement first evaluates all its expressions |
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901 and only then the assignments are performed. |
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902 Thus the code |
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903 |
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904 <pre> |
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905 i = 3 |
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906 i, a[i] = i+1, 20 |
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907 </pre><p> |
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908 sets <code>a[3]</code> to 20, without affecting <code>a[4]</code> |
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909 because the <code>i</code> in <code>a[i]</code> is evaluated (to 3) |
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910 before it is assigned 4. |
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911 Similarly, the line |
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912 |
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913 <pre> |
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914 x, y = y, x |
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915 </pre><p> |
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916 exchanges the values of <code>x</code> and <code>y</code>, |
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917 and |
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918 |
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919 <pre> |
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920 x, y, z = y, z, x |
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921 </pre><p> |
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922 cyclically permutes the values of <code>x</code>, <code>y</code>, and <code>z</code>. |
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923 |
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924 |
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925 <p> |
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926 The meaning of assignments to global variables |
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927 and table fields can be changed via metatables. |
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928 An assignment to an indexed variable <code>t[i] = val</code> is equivalent to |
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929 <code>settable_event(t,i,val)</code>. |
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930 (See <a href="#2.4">§2.4</a> for a complete description of the |
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931 <code>settable_event</code> function. |
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932 This function is not defined or callable in Lua. |
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933 We use it here only for explanatory purposes.) |
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934 |
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935 |
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936 <p> |
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937 An assignment to a global name <code>x = val</code> |
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938 is equivalent to the assignment |
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939 <code>_ENV.x = val</code> (see <a href="#2.2">§2.2</a>). |
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940 |
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941 |
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942 |
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943 |
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944 |
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945 <h3>3.3.4 – <a name="3.3.4">Control Structures</a></h3><p> |
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946 The control structures |
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947 <b>if</b>, <b>while</b>, and <b>repeat</b> have the usual meaning and |
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948 familiar syntax: |
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949 |
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950 |
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951 |
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952 |
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953 <pre> |
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954 stat ::= <b>while</b> exp <b>do</b> block <b>end</b> |
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955 stat ::= <b>repeat</b> block <b>until</b> exp |
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956 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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957 </pre><p> |
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958 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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959 |
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960 |
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961 <p> |
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962 The condition expression of a |
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963 control structure can return any value. |
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964 Both <b>false</b> and <b>nil</b> are considered false. |
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965 All values different from <b>nil</b> and <b>false</b> are considered true |
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966 (in particular, the number 0 and the empty string are also true). |
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967 |
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968 |
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969 <p> |
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970 In the <b>repeat</b>–<b>until</b> loop, |
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971 the inner block does not end at the <b>until</b> keyword, |
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972 but only after the condition. |
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973 So, the condition can refer to local variables |
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974 declared inside the loop block. |
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975 |
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976 |
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977 <p> |
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978 The <b>goto</b> statement transfers the program control to a label. |
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979 For syntactical reasons, |
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980 labels in Lua are considered statements too: |
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981 |
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982 |
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983 |
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984 <pre> |
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985 stat ::= <b>goto</b> Name |
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986 stat ::= label |
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987 label ::= ‘<b>::</b>’ Name ‘<b>::</b>’ |
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988 </pre> |
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989 |
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990 <p> |
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991 A label is visible in the entire block where it is defined, |
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992 except |
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993 inside nested blocks where a label with the same name is defined and |
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994 inside nested functions. |
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995 A goto may jump to any visible label as long as it does not |
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996 enter into the scope of a local variable. |
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997 |
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998 |
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999 <p> |
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1000 Labels and empty statements are called <em>void statements</em>, |
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1001 as they perform no actions. |
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1002 |
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1003 |
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1004 <p> |
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1005 The <b>break</b> statement terminates the execution of a |
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1006 <b>while</b>, <b>repeat</b>, or <b>for</b> loop, |
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1007 skipping to the next statement after the loop: |
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1008 |
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1009 |
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1010 <pre> |
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1011 stat ::= <b>break</b> |
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1012 </pre><p> |
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1013 A <b>break</b> ends the innermost enclosing loop. |
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1014 |
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1015 |
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1016 <p> |
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1017 The <b>return</b> statement is used to return values |
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1018 from a function or a chunk |
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1019 (which is an anonymous function). |
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1020 |
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1021 Functions can return more than one value, |
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1022 so the syntax for the <b>return</b> statement is |
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1023 |
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1024 <pre> |
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1025 stat ::= <b>return</b> [explist] [‘<b>;</b>’] |
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1026 </pre> |
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1027 |
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1028 <p> |
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1029 The <b>return</b> statement can only be written |
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1030 as the last statement of a block. |
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1031 If it is really necessary to <b>return</b> in the middle of a block, |
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1032 then an explicit inner block can be used, |
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1033 as in the idiom <code>do return end</code>, |
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1034 because now <b>return</b> is the last statement in its (inner) block. |
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1035 |
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1036 |
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1037 |
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1038 |
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1039 |
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1040 <h3>3.3.5 – <a name="3.3.5">For Statement</a></h3> |
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1041 |
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1042 <p> |
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1043 |
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1044 The <b>for</b> statement has two forms: |
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1045 one numeric and one generic. |
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1046 |
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1047 |
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1048 <p> |
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1049 The numeric <b>for</b> loop repeats a block of code while a |
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1050 control variable runs through an arithmetic progression. |
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1051 It has the following syntax: |
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1052 |
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1053 <pre> |
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1054 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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1055 </pre><p> |
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1056 The <em>block</em> is repeated for <em>name</em> starting at the value of |
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1057 the first <em>exp</em>, until it passes the second <em>exp</em> by steps of the |
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1058 third <em>exp</em>. |
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1059 More precisely, a <b>for</b> statement like |
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1060 |
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1061 <pre> |
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1062 for v = <em>e1</em>, <em>e2</em>, <em>e3</em> do <em>block</em> end |
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1063 </pre><p> |
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1064 is equivalent to the code: |
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1065 |
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1066 <pre> |
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1067 do |
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1068 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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1069 if not (<em>var</em> and <em>limit</em> and <em>step</em>) then error() end |
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1070 <em>var</em> = <em>var</em> - <em>step</em> |
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1071 while true do |
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1072 <em>var</em> = <em>var</em> + <em>step</em> |
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1073 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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1074 break |
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1075 end |
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1076 local v = <em>var</em> |
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1077 <em>block</em> |
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1078 end |
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1079 end |
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1080 </pre> |
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1081 |
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1082 <p> |
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1083 Note the following: |
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1084 |
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1085 <ul> |
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1086 |
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1087 <li> |
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1088 All three control expressions are evaluated only once, |
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1089 before the loop starts. |
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1090 They must all result in numbers. |
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1091 </li> |
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1092 |
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1093 <li> |
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1094 <code><em>var</em></code>, <code><em>limit</em></code>, and <code><em>step</em></code> are invisible variables. |
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1095 The names shown here are for explanatory purposes only. |
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1096 </li> |
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1097 |
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1098 <li> |
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1099 If the third expression (the step) is absent, |
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1100 then a step of 1 is used. |
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1101 </li> |
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1102 |
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1103 <li> |
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1104 You can use <b>break</b> and <b>goto</b> to exit a <b>for</b> loop. |
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1105 </li> |
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1106 |
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1107 <li> |
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1108 The loop variable <code>v</code> is local to the loop body. |
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1109 If you need its value after the loop, |
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1110 assign it to another variable before exiting the loop. |
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1111 </li> |
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1112 |
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1113 </ul> |
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1114 |
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1115 <p> |
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1116 The generic <b>for</b> statement works over functions, |
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1117 called <em>iterators</em>. |
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1118 On each iteration, the iterator function is called to produce a new value, |
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1119 stopping when this new value is <b>nil</b>. |
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1120 The generic <b>for</b> loop has the following syntax: |
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1121 |
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1122 <pre> |
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1123 stat ::= <b>for</b> namelist <b>in</b> explist <b>do</b> block <b>end</b> |
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1124 namelist ::= Name {‘<b>,</b>’ Name} |
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1125 </pre><p> |
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1126 A <b>for</b> statement like |
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1127 |
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1128 <pre> |
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1129 for <em>var_1</em>, ···, <em>var_n</em> in <em>explist</em> do <em>block</em> end |
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1130 </pre><p> |
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1131 is equivalent to the code: |
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1132 |
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1133 <pre> |
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1134 do |
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1135 local <em>f</em>, <em>s</em>, <em>var</em> = <em>explist</em> |
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1136 while true do |
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1137 local <em>var_1</em>, ···, <em>var_n</em> = <em>f</em>(<em>s</em>, <em>var</em>) |
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1138 if <em>var_1</em> == nil then break end |
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1139 <em>var</em> = <em>var_1</em> |
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1140 <em>block</em> |
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1141 end |
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1142 end |
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1143 </pre><p> |
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1144 Note the following: |
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1145 |
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1146 <ul> |
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1147 |
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1148 <li> |
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1149 <code><em>explist</em></code> is evaluated only once. |
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1150 Its results are an <em>iterator</em> function, |
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1151 a <em>state</em>, |
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1152 and an initial value for the first <em>iterator variable</em>. |
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1153 </li> |
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1154 |
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1155 <li> |
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1156 <code><em>f</em></code>, <code><em>s</em></code>, and <code><em>var</em></code> are invisible variables. |
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1157 The names are here for explanatory purposes only. |
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1158 </li> |
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1159 |
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1160 <li> |
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1161 You can use <b>break</b> to exit a <b>for</b> loop. |
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1162 </li> |
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1163 |
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1164 <li> |
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1165 The loop variables <code><em>var_i</em></code> are local to the loop; |
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1166 you cannot use their values after the <b>for</b> ends. |
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1167 If you need these values, |
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1168 then assign them to other variables before breaking or exiting the loop. |
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1169 </li> |
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1170 |
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1171 </ul> |
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1172 |
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1173 |
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1174 |
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1175 |
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1176 <h3>3.3.6 – <a name="3.3.6">Function Calls as Statements</a></h3><p> |
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1177 To allow possible side-effects, |
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1178 function calls can be executed as statements: |
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1179 |
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1180 <pre> |
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1181 stat ::= functioncall |
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1182 </pre><p> |
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1183 In this case, all returned values are thrown away. |
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1184 Function calls are explained in <a href="#3.4.10">§3.4.10</a>. |
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1185 |
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1186 |
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1187 |
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1188 |
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1189 |
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1190 <h3>3.3.7 – <a name="3.3.7">Local Declarations</a></h3><p> |
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1191 Local variables can be declared anywhere inside a block. |
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1192 The declaration can include an initial assignment: |
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1193 |
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1194 <pre> |
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1195 stat ::= <b>local</b> namelist [‘<b>=</b>’ explist] |
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1196 </pre><p> |
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1197 If present, an initial assignment has the same semantics |
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1198 of a multiple assignment (see <a href="#3.3.3">§3.3.3</a>). |
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1199 Otherwise, all variables are initialized with <b>nil</b>. |
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1200 |
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1201 |
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1202 <p> |
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1203 A chunk is also a block (see <a href="#3.3.2">§3.3.2</a>), |
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1204 and so local variables can be declared in a chunk outside any explicit block. |
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1205 |
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1206 |
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1207 <p> |
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1208 The visibility rules for local variables are explained in <a href="#3.5">§3.5</a>. |
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1209 |
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1210 |
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1211 |
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1212 |
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1213 |
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1214 |
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1215 |
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1216 <h2>3.4 – <a name="3.4">Expressions</a></h2> |
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1217 |
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1218 <p> |
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1219 The basic expressions in Lua are the following: |
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1220 |
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1221 <pre> |
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1222 exp ::= prefixexp |
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1223 exp ::= <b>nil</b> | <b>false</b> | <b>true</b> |
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1224 exp ::= Numeral |
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1225 exp ::= LiteralString |
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1226 exp ::= functiondef |
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1227 exp ::= tableconstructor |
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1228 exp ::= ‘<b>...</b>’ |
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1229 exp ::= exp binop exp |
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1230 exp ::= unop exp |
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1231 prefixexp ::= var | functioncall | ‘<b>(</b>’ exp ‘<b>)</b>’ |
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1232 </pre> |
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1233 |
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1234 <p> |
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1235 Numerals and literal strings are explained in <a href="#3.1">§3.1</a>; |
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1236 variables are explained in <a href="#3.2">§3.2</a>; |
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1237 function definitions are explained in <a href="#3.4.11">§3.4.11</a>; |
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1238 function calls are explained in <a href="#3.4.10">§3.4.10</a>; |
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1239 table constructors are explained in <a href="#3.4.9">§3.4.9</a>. |
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1240 Vararg expressions, |
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1241 denoted by three dots ('<code>...</code>'), can only be used when |
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1242 directly inside a vararg function; |
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1243 they are explained in <a href="#3.4.11">§3.4.11</a>. |
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1244 |
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1245 |
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1246 <p> |
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1247 Binary operators comprise arithmetic operators (see <a href="#3.4.1">§3.4.1</a>), |
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1248 bitwise operators (see <a href="#3.4.2">§3.4.2</a>), |
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1249 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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1250 and the concatenation operator (see <a href="#3.4.6">§3.4.6</a>). |
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1251 Unary operators comprise the unary minus (see <a href="#3.4.1">§3.4.1</a>), |
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1252 the unary bitwise not (see <a href="#3.4.2">§3.4.2</a>), |
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1253 the unary logical <b>not</b> (see <a href="#3.4.5">§3.4.5</a>), |
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1254 and the unary <em>length operator</em> (see <a href="#3.4.7">§3.4.7</a>). |
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1255 |
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1256 |
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1257 <p> |
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1258 Both function calls and vararg expressions can result in multiple values. |
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1259 If a function call is used as a statement (see <a href="#3.3.6">§3.3.6</a>), |
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1260 then its return list is adjusted to zero elements, |
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1261 thus discarding all returned values. |
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1262 If an expression is used as the last (or the only) element |
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1263 of a list of expressions, |
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1264 then no adjustment is made |
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1265 (unless the expression is enclosed in parentheses). |
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1266 In all other contexts, |
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1267 Lua adjusts the result list to one element, |
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1268 either discarding all values except the first one |
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1269 or adding a single <b>nil</b> if there are no values. |
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1270 |
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1271 |
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1272 <p> |
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1273 Here are some examples: |
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1274 |
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1275 <pre> |
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1276 f() -- adjusted to 0 results |
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1277 g(f(), x) -- f() is adjusted to 1 result |
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1278 g(x, f()) -- g gets x plus all results from f() |
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1279 a,b,c = f(), x -- f() is adjusted to 1 result (c gets nil) |
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1280 a,b = ... -- a gets the first vararg parameter, b gets |
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1281 -- the second (both a and b can get nil if there |
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1282 -- is no corresponding vararg parameter) |
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1283 |
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1284 a,b,c = x, f() -- f() is adjusted to 2 results |
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1285 a,b,c = f() -- f() is adjusted to 3 results |
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1286 return f() -- returns all results from f() |
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1287 return ... -- returns all received vararg parameters |
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1288 return x,y,f() -- returns x, y, and all results from f() |
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1289 {f()} -- creates a list with all results from f() |
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1290 {...} -- creates a list with all vararg parameters |
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1291 {f(), nil} -- f() is adjusted to 1 result |
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1292 </pre> |
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1293 |
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1294 <p> |
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1295 Any expression enclosed in parentheses always results in only one value. |
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1296 Thus, |
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1297 <code>(f(x,y,z))</code> is always a single value, |
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1298 even if <code>f</code> returns several values. |
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1299 (The value of <code>(f(x,y,z))</code> is the first value returned by <code>f</code> |
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1300 or <b>nil</b> if <code>f</code> does not return any values.) |
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1301 |
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1302 |
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1303 |
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1304 <h3>3.4.1 – <a name="3.4.1">Arithmetic Operators</a></h3><p> |
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1305 Lua supports the following arithmetic operators: |
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1306 |
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1307 <ul> |
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1308 <li><b><code>+</code>: </b>addition</li> |
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1309 <li><b><code>-</code>: </b>subtraction</li> |
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1310 <li><b><code>*</code>: </b>multiplication</li> |
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1311 <li><b><code>/</code>: </b>float division</li> |
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1312 <li><b><code>//</code>: </b>floor division</li> |
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1313 <li><b><code>%</code>: </b>modulo</li> |
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1314 <li><b><code>^</code>: </b>exponentiation</li> |
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1315 <li><b><code>-</code>: </b>unary minus</li> |
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1316 </ul> |
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1317 |
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1318 <p> |
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1319 With the exception of exponentiation and float division, |
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1320 the arithmetic operators work as follows: |
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1321 If both operands are integers, |
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1322 the operation is performed over integers and the result is an integer. |
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1323 Otherwise, if both operands are numbers |
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1324 or strings that can be converted to |
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1325 numbers (see <a href="#3.4.3">§3.4.3</a>), |
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1326 then they are converted to floats, |
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1327 the operation is performed following the usual rules |
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1328 for floating-point arithmetic |
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1329 (usually the IEEE 754 standard), |
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1330 and the result is a float. |
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1331 |
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1332 |
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1333 <p> |
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1334 Exponentiation and float division (<code>/</code>) |
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1335 always convert their operands to floats |
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1336 and the result is always a float. |
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1337 Exponentiation uses the ISO C function <code>pow</code>, |
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1338 so that it works for non-integer exponents too. |
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1339 |
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1340 |
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1341 <p> |
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1342 Floor division (<code>//</code>) is a division |
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1343 that rounds the quotient towards minus infinite, |
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1344 that is, the floor of the division of its operands. |
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1345 |
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1346 |
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1347 <p> |
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1348 Modulo is defined as the remainder of a division |
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1349 that rounds the quotient towards minus infinite (floor division). |
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1350 |
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1351 |
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1352 <p> |
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1353 In case of overflows in integer arithmetic, |
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1354 all operations <em>wrap around</em>, |
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1355 according to the usual rules of two-complement arithmetic. |
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1356 (In other words, |
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1357 they return the unique representable integer |
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1358 that is equal modulo <em>2<sup>64</sup></em> to the mathematical result.) |
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1359 |
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1360 |
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1361 |
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1362 <h3>3.4.2 – <a name="3.4.2">Bitwise Operators</a></h3><p> |
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1363 Lua supports the following bitwise operators: |
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1364 |
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1365 <ul> |
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1366 <li><b><code>&</code>: </b>bitwise and</li> |
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1367 <li><b><code>|</code>: </b>bitwise or</li> |
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1368 <li><b><code>~</code>: </b>bitwise exclusive or</li> |
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1369 <li><b><code>>></code>: </b>right shift</li> |
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1370 <li><b><code><<</code>: </b>left shift</li> |
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1371 <li><b><code>~</code>: </b>unary bitwise not</li> |
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1372 </ul> |
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1373 |
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1374 <p> |
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1375 All bitwise operations convert its operands to integers |
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1376 (see <a href="#3.4.3">§3.4.3</a>), |
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1377 operate on all bits of those integers, |
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1378 and result in an integer. |
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1379 |
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1380 |
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1381 <p> |
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1382 Both right and left shifts fill the vacant bits with zeros. |
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1383 Negative displacements shift to the other direction; |
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1384 displacements with absolute values equal to or higher than |
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1385 the number of bits in an integer |
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1386 result in zero (as all bits are shifted out). |
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1387 |
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1388 |
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1389 |
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1390 |
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1391 |
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1392 <h3>3.4.3 – <a name="3.4.3">Coercions and Conversions</a></h3><p> |
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1393 Lua provides some automatic conversions between some |
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1394 types and representations at run time. |
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1395 Bitwise operators always convert float operands to integers. |
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1396 Exponentiation and float division |
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1397 always convert integer operands to floats. |
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1398 All other arithmetic operations applied to mixed numbers |
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1399 (integers and floats) convert the integer operand to a float; |
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1400 this is called the <em>usual rule</em>. |
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1401 The C API also converts both integers to floats and |
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1402 floats to integers, as needed. |
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1403 Moreover, string concatenation accepts numbers as arguments, |
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1404 besides strings. |
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1405 |
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1406 |
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1407 <p> |
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1408 Lua also converts strings to numbers, |
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1409 whenever a number is expected. |
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1410 |
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1411 |
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1412 <p> |
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1413 In a conversion from integer to float, |
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1414 if the integer value has an exact representation as a float, |
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1415 that is the result. |
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1416 Otherwise, |
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1417 the conversion gets the nearest higher or |
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1418 the nearest lower representable value. |
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1419 This kind of conversion never fails. |
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1420 |
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1421 |
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1422 <p> |
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1423 The conversion from float to integer |
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1424 checks whether the float has an exact representation as an integer |
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1425 (that is, the float has an integral value and |
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1426 it is in the range of integer representation). |
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1427 If it does, that representation is the result. |
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1428 Otherwise, the conversion fails. |
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1429 |
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1430 |
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1431 <p> |
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1432 The conversion from strings to numbers goes as follows: |
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1433 First, the string is converted to an integer or a float, |
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1434 following its syntax and the rules of the Lua lexer. |
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1435 (The string may have also leading and trailing spaces and a sign.) |
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1436 Then, the resulting number is converted to the required type |
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1437 (float or integer) according to the previous rules. |
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1438 |
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1439 |
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1440 <p> |
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1441 The conversion from numbers to strings uses a |
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1442 non-specified human-readable format. |
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1443 For complete control over how numbers are converted to strings, |
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1444 use the <code>format</code> function from the string library |
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1445 (see <a href="#pdf-string.format"><code>string.format</code></a>). |
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1446 |
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1447 |
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1448 |
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1449 |
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1450 |
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1451 <h3>3.4.4 – <a name="3.4.4">Relational Operators</a></h3><p> |
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1452 Lua supports the following relational operators: |
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1453 |
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1454 <ul> |
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1455 <li><b><code>==</code>: </b>equality</li> |
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1456 <li><b><code>~=</code>: </b>inequality</li> |
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1457 <li><b><code><</code>: </b>less than</li> |
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1458 <li><b><code>></code>: </b>greater than</li> |
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1459 <li><b><code><=</code>: </b>less or equal</li> |
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1460 <li><b><code>>=</code>: </b>greater or equal</li> |
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1461 </ul><p> |
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1462 These operators always result in <b>false</b> or <b>true</b>. |
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1463 |
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1464 |
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1465 <p> |
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1466 Equality (<code>==</code>) first compares the type of its operands. |
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1467 If the types are different, then the result is <b>false</b>. |
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1468 Otherwise, the values of the operands are compared. |
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1469 Strings are compared in the obvious way. |
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1470 Numbers follow the usual rule for binary operations: |
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1471 if both operands are integers, |
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1472 they are compared as integers; |
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1473 otherwise, they are converted to floats |
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1474 and compared as such. |
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1475 |
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1476 |
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1477 <p> |
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1478 Tables, userdata, and threads |
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1479 are compared by reference: |
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1480 two objects are considered equal only if they are the same object. |
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1481 Every time you create a new object |
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1482 (a table, userdata, or thread), |
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1483 this new object is different from any previously existing object. |
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1484 Closures with the same reference are always equal. |
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1485 Closures with any detectable difference |
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1486 (different behavior, different definition) are always different. |
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1487 |
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1488 |
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1489 <p> |
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1490 You can change the way that Lua compares tables and userdata |
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1491 by using the "eq" metamethod (see <a href="#2.4">§2.4</a>). |
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1492 |
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1493 |
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1494 <p> |
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1495 Equality comparisons do not convert strings to numbers |
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1496 or vice versa. |
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1497 Thus, <code>"0"==0</code> evaluates to <b>false</b>, |
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1498 and <code>t[0]</code> and <code>t["0"]</code> denote different |
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1499 entries in a table. |
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1500 |
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1501 |
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1502 <p> |
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1503 The operator <code>~=</code> is exactly the negation of equality (<code>==</code>). |
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1504 |
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1505 |
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1506 <p> |
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1507 The order operators work as follows. |
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1508 If both arguments are numbers, |
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1509 then they are compared following |
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1510 the usual rule for binary operations. |
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1511 Otherwise, if both arguments are strings, |
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1512 then their values are compared according to the current locale. |
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1513 Otherwise, Lua tries to call the "lt" or the "le" |
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1514 metamethod (see <a href="#2.4">§2.4</a>). |
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1515 A comparison <code>a > b</code> is translated to <code>b < a</code> |
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1516 and <code>a >= b</code> is translated to <code>b <= a</code>. |
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1517 |
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1518 |
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1519 |
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1520 |
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1521 |
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1522 <h3>3.4.5 – <a name="3.4.5">Logical Operators</a></h3><p> |
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1523 The logical operators in Lua are |
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1524 <b>and</b>, <b>or</b>, and <b>not</b>. |
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1525 Like the control structures (see <a href="#3.3.4">§3.3.4</a>), |
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1526 all logical operators consider both <b>false</b> and <b>nil</b> as false |
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1527 and anything else as true. |
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1528 |
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1529 |
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1530 <p> |
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1531 The negation operator <b>not</b> always returns <b>false</b> or <b>true</b>. |
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1532 The conjunction operator <b>and</b> returns its first argument |
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1533 if this value is <b>false</b> or <b>nil</b>; |
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1534 otherwise, <b>and</b> returns its second argument. |
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1535 The disjunction operator <b>or</b> returns its first argument |
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1536 if this value is different from <b>nil</b> and <b>false</b>; |
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1537 otherwise, <b>or</b> returns its second argument. |
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1538 Both <b>and</b> and <b>or</b> use short-circuit evaluation; |
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1539 that is, |
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1540 the second operand is evaluated only if necessary. |
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1541 Here are some examples: |
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1542 |
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1543 <pre> |
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1544 10 or 20 --> 10 |
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1545 10 or error() --> 10 |
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1546 nil or "a" --> "a" |
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1547 nil and 10 --> nil |
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1548 false and error() --> false |
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1549 false and nil --> false |
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1550 false or nil --> nil |
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1551 10 and 20 --> 20 |
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1552 </pre><p> |
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1553 (In this manual, |
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1554 <code>--></code> indicates the result of the preceding expression.) |
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1555 |
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1556 |
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1557 |
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1558 |
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1559 |
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1560 <h3>3.4.6 – <a name="3.4.6">Concatenation</a></h3><p> |
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1561 The string concatenation operator in Lua is |
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1562 denoted by two dots ('<code>..</code>'). |
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1563 If both operands are strings or numbers, then they are converted to |
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1564 strings according to the rules described in <a href="#3.4.3">§3.4.3</a>. |
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1565 Otherwise, the <code>__concat</code> metamethod is called (see <a href="#2.4">§2.4</a>). |
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1566 |
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1567 |
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1568 |
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1569 |
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1570 |
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1571 <h3>3.4.7 – <a name="3.4.7">The Length Operator</a></h3> |
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1572 |
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1573 <p> |
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1574 The length operator is denoted by the unary prefix operator <code>#</code>. |
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1575 The length of a string is its number of bytes |
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1576 (that is, the usual meaning of string length when each |
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1577 character is one byte). |
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1578 |
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1579 |
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1580 <p> |
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1581 A program can modify the behavior of the length operator for |
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1582 any value but strings through the <code>__len</code> metamethod (see <a href="#2.4">§2.4</a>). |
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1583 |
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1584 |
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1585 <p> |
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1586 Unless a <code>__len</code> metamethod is given, |
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1587 the length of a table <code>t</code> is only defined if the |
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1588 table is a <em>sequence</em>, |
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1589 that is, |
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1590 the set of its positive numeric keys is equal to <em>{1..n}</em> |
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1591 for some non-negative integer <em>n</em>. |
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1592 In that case, <em>n</em> is its length. |
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1593 Note that a table like |
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1594 |
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1595 <pre> |
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1596 {10, 20, nil, 40} |
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1597 </pre><p> |
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1598 is not a sequence, because it has the key <code>4</code> |
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1599 but does not have the key <code>3</code>. |
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1600 (So, there is no <em>n</em> such that the set <em>{1..n}</em> is equal |
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1601 to the set of positive numeric keys of that table.) |
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1602 Note, however, that non-numeric keys do not interfere |
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1603 with whether a table is a sequence. |
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1604 |
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1605 |
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1606 |
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1607 |
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1608 |
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1609 <h3>3.4.8 – <a name="3.4.8">Precedence</a></h3><p> |
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1610 Operator precedence in Lua follows the table below, |
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1611 from lower to higher priority: |
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1612 |
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1613 <pre> |
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1614 or |
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1615 and |
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1616 < > <= >= ~= == |
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1617 | |
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1618 ~ |
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1619 & |
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1620 << >> |
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1621 .. |
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1622 + - |
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1623 * / // % |
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1624 unary operators (not # - ~) |
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1625 ^ |
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1626 </pre><p> |
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1627 As usual, |
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1628 you can use parentheses to change the precedences of an expression. |
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1629 The concatenation ('<code>..</code>') and exponentiation ('<code>^</code>') |
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1630 operators are right associative. |
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1631 All other binary operators are left associative. |
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1632 |
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1633 |
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1634 |
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1635 |
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1636 |
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1637 <h3>3.4.9 – <a name="3.4.9">Table Constructors</a></h3><p> |
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1638 Table constructors are expressions that create tables. |
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1639 Every time a constructor is evaluated, a new table is created. |
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1640 A constructor can be used to create an empty table |
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1641 or to create a table and initialize some of its fields. |
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1642 The general syntax for constructors is |
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1643 |
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1644 <pre> |
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1645 tableconstructor ::= ‘<b>{</b>’ [fieldlist] ‘<b>}</b>’ |
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1646 fieldlist ::= field {fieldsep field} [fieldsep] |
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1647 field ::= ‘<b>[</b>’ exp ‘<b>]</b>’ ‘<b>=</b>’ exp | Name ‘<b>=</b>’ exp | exp |
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1648 fieldsep ::= ‘<b>,</b>’ | ‘<b>;</b>’ |
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1649 </pre> |
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1650 |
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1651 <p> |
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1652 Each field of the form <code>[exp1] = exp2</code> adds to the new table an entry |
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1653 with key <code>exp1</code> and value <code>exp2</code>. |
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1654 A field of the form <code>name = exp</code> is equivalent to |
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1655 <code>["name"] = exp</code>. |
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1656 Finally, fields of the form <code>exp</code> are equivalent to |
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1657 <code>[i] = exp</code>, where <code>i</code> are consecutive integers |
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1658 starting with 1. |
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1659 Fields in the other formats do not affect this counting. |
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1660 For example, |
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1661 |
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1662 <pre> |
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1663 a = { [f(1)] = g; "x", "y"; x = 1, f(x), [30] = 23; 45 } |
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1664 </pre><p> |
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1665 is equivalent to |
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1666 |
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1667 <pre> |
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1668 do |
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1669 local t = {} |
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1670 t[f(1)] = g |
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1671 t[1] = "x" -- 1st exp |
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1672 t[2] = "y" -- 2nd exp |
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1673 t.x = 1 -- t["x"] = 1 |
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1674 t[3] = f(x) -- 3rd exp |
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1675 t[30] = 23 |
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1676 t[4] = 45 -- 4th exp |
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1677 a = t |
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1678 end |
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1679 </pre> |
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1680 |
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1681 <p> |
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1682 The order of the assignments in a constructor is undefined. |
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1683 (This order would be relevant only when there are repeated keys.) |
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1684 |
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1685 |
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1686 <p> |
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1687 If the last field in the list has the form <code>exp</code> |
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1688 and the expression is a function call or a vararg expression, |
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1689 then all values returned by this expression enter the list consecutively |
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1690 (see <a href="#3.4.10">§3.4.10</a>). |
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1691 |
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1692 |
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1693 <p> |
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1694 The field list can have an optional trailing separator, |
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1695 as a convenience for machine-generated code. |
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1696 |
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|
1697 |
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|
1698 |
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|
1699 |
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1700 |
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1701 <h3>3.4.10 – <a name="3.4.10">Function Calls</a></h3><p> |
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1702 A function call in Lua has the following syntax: |
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1703 |
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1704 <pre> |
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1705 functioncall ::= prefixexp args |
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1706 </pre><p> |
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1707 In a function call, |
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1708 first prefixexp and args are evaluated. |
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1709 If the value of prefixexp has type <em>function</em>, |
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1710 then this function is called |
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1711 with the given arguments. |
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1712 Otherwise, the prefixexp "call" metamethod is called, |
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1713 having as first parameter the value of prefixexp, |
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1714 followed by the original call arguments |
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1715 (see <a href="#2.4">§2.4</a>). |
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1716 |
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1717 |
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1718 <p> |
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1719 The form |
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1720 |
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1721 <pre> |
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1722 functioncall ::= prefixexp ‘<b>:</b>’ Name args |
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1723 </pre><p> |
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1724 can be used to call "methods". |
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1725 A call <code>v:name(<em>args</em>)</code> |
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1726 is syntactic sugar for <code>v.name(v,<em>args</em>)</code>, |
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1727 except that <code>v</code> is evaluated only once. |
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1728 |
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1729 |
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1730 <p> |
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1731 Arguments have the following syntax: |
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1732 |
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1733 <pre> |
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1734 args ::= ‘<b>(</b>’ [explist] ‘<b>)</b>’ |
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1735 args ::= tableconstructor |
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1736 args ::= LiteralString |
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1737 </pre><p> |
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1738 All argument expressions are evaluated before the call. |
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1739 A call of the form <code>f{<em>fields</em>}</code> is |
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1740 syntactic sugar for <code>f({<em>fields</em>})</code>; |
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1741 that is, the argument list is a single new table. |
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1742 A call of the form <code>f'<em>string</em>'</code> |
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1743 (or <code>f"<em>string</em>"</code> or <code>f[[<em>string</em>]]</code>) |
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1744 is syntactic sugar for <code>f('<em>string</em>')</code>; |
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1745 that is, the argument list is a single literal string. |
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1746 |
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1747 |
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1748 <p> |
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1749 A call of the form <code>return <em>functioncall</em></code> is called |
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1750 a <em>tail call</em>. |
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1751 Lua implements <em>proper tail calls</em> |
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1752 (or <em>proper tail recursion</em>): |
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1753 in a tail call, |
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1754 the called function reuses the stack entry of the calling function. |
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1755 Therefore, there is no limit on the number of nested tail calls that |
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1756 a program can execute. |
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1757 However, a tail call erases any debug information about the |
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1758 calling function. |
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1759 Note that a tail call only happens with a particular syntax, |
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1760 where the <b>return</b> has one single function call as argument; |
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1761 this syntax makes the calling function return exactly |
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1762 the returns of the called function. |
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1763 So, none of the following examples are tail calls: |
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1764 |
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1765 <pre> |
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1766 return (f(x)) -- results adjusted to 1 |
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1767 return 2 * f(x) |
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1768 return x, f(x) -- additional results |
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1769 f(x); return -- results discarded |
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1770 return x or f(x) -- results adjusted to 1 |
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1771 </pre> |
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1772 |
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1773 |
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1774 |
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1775 |
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1776 <h3>3.4.11 – <a name="3.4.11">Function Definitions</a></h3> |
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1777 |
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1778 <p> |
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1779 The syntax for function definition is |
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1780 |
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1781 <pre> |
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1782 functiondef ::= <b>function</b> funcbody |
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1783 funcbody ::= ‘<b>(</b>’ [parlist] ‘<b>)</b>’ block <b>end</b> |
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1784 </pre> |
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1785 |
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1786 <p> |
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1787 The following syntactic sugar simplifies function definitions: |
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1788 |
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1789 <pre> |
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1790 stat ::= <b>function</b> funcname funcbody |
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1791 stat ::= <b>local</b> <b>function</b> Name funcbody |
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1792 funcname ::= Name {‘<b>.</b>’ Name} [‘<b>:</b>’ Name] |
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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 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 f = function () <em>body</em> end |
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1803 </pre><p> |
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1804 The statement |
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1805 |
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1806 <pre> |
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1807 function t.a.b.c.f () <em>body</em> end |
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1808 </pre><p> |
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1809 translates to |
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1810 |
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1811 <pre> |
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1812 t.a.b.c.f = function () <em>body</em> end |
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1813 </pre><p> |
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1814 The statement |
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1815 |
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1816 <pre> |
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1817 local function f () <em>body</em> end |
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1818 </pre><p> |
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1819 translates to |
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1820 |
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1821 <pre> |
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1822 local f; f = function () <em>body</em> end |
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1823 </pre><p> |
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1824 not to |
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1825 |
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1826 <pre> |
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1827 local f = function () <em>body</em> end |
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1828 </pre><p> |
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1829 (This only makes a difference when the body of the function |
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1830 contains references to <code>f</code>.) |
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1831 |
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1832 |
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1833 <p> |
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1834 A function definition is an executable expression, |
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1835 whose value has type <em>function</em>. |
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1836 When Lua precompiles a chunk, |
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1837 all its function bodies are precompiled too. |
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1838 Then, whenever Lua executes the function definition, |
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1839 the function is <em>instantiated</em> (or <em>closed</em>). |
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1840 This function instance (or <em>closure</em>) |
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1841 is the final value of the expression. |
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1842 |
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1843 |
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1844 <p> |
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1845 Parameters act as local variables that are |
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1846 initialized with the argument values: |
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1847 |
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1848 <pre> |
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1849 parlist ::= namelist [‘<b>,</b>’ ‘<b>...</b>’] | ‘<b>...</b>’ |
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1850 </pre><p> |
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1851 When a function is called, |
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1852 the list of arguments is adjusted to |
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1853 the length of the list of parameters, |
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1854 unless the function is a <em>vararg function</em>, |
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1855 which is indicated by three dots ('<code>...</code>') |
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1856 at the end of its parameter list. |
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1857 A vararg function does not adjust its argument list; |
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1858 instead, it collects all extra arguments and supplies them |
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1859 to the function through a <em>vararg expression</em>, |
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1860 which is also written as three dots. |
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1861 The value of this expression is a list of all actual extra arguments, |
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1862 similar to a function with multiple results. |
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1863 If a vararg expression is used inside another expression |
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1864 or in the middle of a list of expressions, |
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1865 then its return list is adjusted to one element. |
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1866 If the expression is used as the last element of a list of expressions, |
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1867 then no adjustment is made |
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1868 (unless that last expression is enclosed in parentheses). |
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1869 |
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1870 |
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1871 <p> |
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1872 As an example, consider the following definitions: |
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1873 |
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1874 <pre> |
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1875 function f(a, b) end |
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1876 function g(a, b, ...) end |
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1877 function r() return 1,2,3 end |
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1878 </pre><p> |
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1879 Then, we have the following mapping from arguments to parameters and |
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1880 to the vararg expression: |
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1881 |
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1882 <pre> |
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1883 CALL PARAMETERS |
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1884 |
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1885 f(3) a=3, b=nil |
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1886 f(3, 4) a=3, b=4 |
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1887 f(3, 4, 5) a=3, b=4 |
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1888 f(r(), 10) a=1, b=10 |
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1889 f(r()) a=1, b=2 |
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1890 |
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1891 g(3) a=3, b=nil, ... --> (nothing) |
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1892 g(3, 4) a=3, b=4, ... --> (nothing) |
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1893 g(3, 4, 5, 8) a=3, b=4, ... --> 5 8 |
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1894 g(5, r()) a=5, b=1, ... --> 2 3 |
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1895 </pre> |
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1896 |
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1897 <p> |
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1898 Results are returned using the <b>return</b> statement (see <a href="#3.3.4">§3.3.4</a>). |
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1899 If control reaches the end of a function |
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1900 without encountering a <b>return</b> statement, |
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1901 then the function returns with no results. |
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1902 |
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1903 |
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1904 <p> |
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1905 |
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1906 There is a system-dependent limit on the number of values |
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1907 that a function may return. |
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1908 This limit is guaranteed to be larger than 1000. |
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1909 |
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1910 |
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1911 <p> |
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1912 The <em>colon</em> syntax |
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1913 is used for defining <em>methods</em>, |
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1914 that is, functions that have an implicit extra parameter <code>self</code>. |
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1915 Thus, the statement |
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1916 |
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1917 <pre> |
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1918 function t.a.b.c:f (<em>params</em>) <em>body</em> end |
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1919 </pre><p> |
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1920 is syntactic sugar for |
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1921 |
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1922 <pre> |
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1923 t.a.b.c.f = function (self, <em>params</em>) <em>body</em> end |
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1924 </pre> |
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1925 |
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1926 |
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1927 |
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1928 |
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1929 |
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1930 |
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1931 <h2>3.5 – <a name="3.5">Visibility Rules</a></h2> |
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1932 |
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1933 <p> |
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1934 |
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1935 Lua is a lexically scoped language. |
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1936 The scope of a local variable begins at the first statement after |
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1937 its declaration and lasts until the last non-void statement |
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1938 of the innermost block that includes the declaration. |
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1939 Consider the following example: |
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1940 |
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1941 <pre> |
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1942 x = 10 -- global variable |
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1943 do -- new block |
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1944 local x = x -- new 'x', with value 10 |
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1945 print(x) --> 10 |
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1946 x = x+1 |
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1947 do -- another block |
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1948 local x = x+1 -- another 'x' |
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1949 print(x) --> 12 |
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1950 end |
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1951 print(x) --> 11 |
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1952 end |
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1953 print(x) --> 10 (the global one) |
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1954 </pre> |
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1955 |
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1956 <p> |
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1957 Notice that, in a declaration like <code>local x = x</code>, |
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1958 the new <code>x</code> being declared is not in scope yet, |
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1959 and so the second <code>x</code> refers to the outside variable. |
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1960 |
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1961 |
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1962 <p> |
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1963 Because of the lexical scoping rules, |
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1964 local variables can be freely accessed by functions |
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1965 defined inside their scope. |
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1966 A local variable used by an inner function is called |
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1967 an <em>upvalue</em>, or <em>external local variable</em>, |
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1968 inside the inner function. |
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1969 |
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1970 |
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1971 <p> |
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1972 Notice that each execution of a <b>local</b> statement |
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1973 defines new local variables. |
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1974 Consider the following example: |
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1975 |
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1976 <pre> |
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1977 a = {} |
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1978 local x = 20 |
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1979 for i=1,10 do |
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1980 local y = 0 |
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1981 a[i] = function () y=y+1; return x+y end |
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1982 end |
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1983 </pre><p> |
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1984 The loop creates ten closures |
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1985 (that is, ten instances of the anonymous function). |
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1986 Each of these closures uses a different <code>y</code> variable, |
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1987 while all of them share the same <code>x</code>. |
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1988 |
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1989 |
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1990 |
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1991 |
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1992 |
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1993 <h1>4 – <a name="4">The Application Program Interface</a></h1> |
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1994 |
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1995 <p> |
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1996 |
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1997 This section describes the C API for Lua, that is, |
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1998 the set of C functions available to the host program to communicate |
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1999 with Lua. |
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2000 All API functions and related types and constants |
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2001 are declared in the header file <a name="pdf-lua.h"><code>lua.h</code></a>. |
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2002 |
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2003 |
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2004 <p> |
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2005 Even when we use the term "function", |
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2006 any facility in the API may be provided as a macro instead. |
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2007 Except where stated otherwise, |
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2008 all such macros use each of their arguments exactly once |
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2009 (except for the first argument, which is always a Lua state), |
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2010 and so do not generate any hidden side-effects. |
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2011 |
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2012 |
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2013 <p> |
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2014 As in most C libraries, |
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2015 the Lua API functions do not check their arguments for validity or consistency. |
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2016 However, you can change this behavior by compiling Lua |
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2017 with the macro <a name="pdf-LUA_USE_APICHECK"><code>LUA_USE_APICHECK</code></a> defined. |
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2018 |
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2019 |
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2020 |
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2021 <h2>4.1 – <a name="4.1">The Stack</a></h2> |
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2022 |
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2023 <p> |
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2024 Lua uses a <em>virtual stack</em> to pass values to and from C. |
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2025 Each element in this stack represents a Lua value |
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2026 (<b>nil</b>, number, string, etc.). |
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2027 |
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2028 |
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2029 <p> |
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2030 Whenever Lua calls C, the called function gets a new stack, |
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2031 which is independent of previous stacks and of stacks of |
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2032 C functions that are still active. |
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2033 This stack initially contains any arguments to the C function |
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2034 and it is where the C function pushes its results |
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2035 to be returned to the caller (see <a href="#lua_CFunction"><code>lua_CFunction</code></a>). |
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2036 |
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2037 |
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2038 <p> |
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2039 For convenience, |
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2040 most query operations in the API do not follow a strict stack discipline. |
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2041 Instead, they can refer to any element in the stack |
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2042 by using an <em>index</em>: |
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2043 A positive index represents an absolute stack position |
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2044 (starting at 1); |
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2045 a negative index represents an offset relative to the top of the stack. |
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2046 More specifically, if the stack has <em>n</em> elements, |
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2047 then index 1 represents the first element |
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2048 (that is, the element that was pushed onto the stack first) |
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2049 and |
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2050 index <em>n</em> represents the last element; |
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2051 index -1 also represents the last element |
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2052 (that is, the element at the top) |
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2053 and index <em>-n</em> represents the first element. |
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2054 |
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2055 |
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2056 |
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2057 |
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2058 |
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2059 <h2>4.2 – <a name="4.2">Stack Size</a></h2> |
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2060 |
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2061 <p> |
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2062 When you interact with the Lua API, |
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2063 you are responsible for ensuring consistency. |
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2064 In particular, |
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2065 <em>you are responsible for controlling stack overflow</em>. |
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2066 You can use the function <a href="#lua_checkstack"><code>lua_checkstack</code></a> |
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2067 to ensure that the stack has enough space for pushing new elements. |
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2068 |
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2069 |
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2070 <p> |
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2071 Whenever Lua calls C, |
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2072 it ensures that the stack has space for |
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2073 at least <a name="pdf-LUA_MINSTACK"><code>LUA_MINSTACK</code></a> extra slots. |
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2074 <code>LUA_MINSTACK</code> is defined as 20, |
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2075 so that usually you do not have to worry about stack space |
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2076 unless your code has loops pushing elements onto the stack. |
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2077 |
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2078 |
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2079 <p> |
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2080 When you call a Lua function |
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2081 without a fixed number of results (see <a href="#lua_call"><code>lua_call</code></a>), |
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2082 Lua ensures that the stack has enough space for all results, |
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2083 but it does not ensure any extra space. |
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2084 So, before pushing anything in the stack after such a call |
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2085 you should use <a href="#lua_checkstack"><code>lua_checkstack</code></a>. |
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2086 |
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2087 |
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2088 |
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2089 |
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2090 |
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2091 <h2>4.3 – <a name="4.3">Valid and Acceptable Indices</a></h2> |
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2092 |
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2093 <p> |
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2094 Any function in the API that receives stack indices |
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2095 works only with <em>valid indices</em> or <em>acceptable indices</em>. |
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2096 |
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2097 |
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2098 <p> |
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2099 A <em>valid index</em> is an index that refers to a |
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2100 real position within the stack, that is, |
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2101 its position lies between 1 and the stack top |
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2102 (<code>1 ≤ abs(index) ≤ top</code>). |
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2103 |
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2104 Usually, functions that can modify the value at an index |
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2105 require valid indices. |
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2106 |
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2107 |
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2108 <p> |
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2109 Unless otherwise noted, |
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2110 any function that accepts valid indices also accepts <em>pseudo-indices</em>, |
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2111 which represent some Lua values that are accessible to C code |
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2112 but which are not in the stack. |
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2113 Pseudo-indices are used to access the registry |
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2114 and the upvalues of a C function (see <a href="#4.4">§4.4</a>). |
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2115 |
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2116 |
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2117 <p> |
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2118 Functions that do not need a specific stack position, |
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2119 but only a value in the stack (e.g., query functions), |
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2120 can be called with acceptable indices. |
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2121 An <em>acceptable index</em> can be any valid index, |
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2122 including the pseudo-indices, |
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2123 but it also can be any positive index after the stack top |
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2124 within the space allocated for the stack, |
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2125 that is, indices up to the stack size. |
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2126 (Note that 0 is never an acceptable index.) |
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2127 Except when noted otherwise, |
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2128 functions in the API work with acceptable indices. |
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2129 |
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2130 |
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2131 <p> |
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2132 Acceptable indices serve to avoid extra tests |
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2133 against the stack top when querying the stack. |
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2134 For instance, a C function can query its third argument |
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2135 without the need to first check whether there is a third argument, |
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2136 that is, without the need to check whether 3 is a valid index. |
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2137 |
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2138 |
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2139 <p> |
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2140 For functions that can be called with acceptable indices, |
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2141 any non-valid index is treated as if it |
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2142 contains a value of a virtual type <a name="pdf-LUA_TNONE"><code>LUA_TNONE</code></a>, |
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2143 which behaves like a nil value. |
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2144 |
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2145 |
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2146 |
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2147 |
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2148 |
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2149 <h2>4.4 – <a name="4.4">C Closures</a></h2> |
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2150 |
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2151 <p> |
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2152 When a C function is created, |
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2153 it is possible to associate some values with it, |
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2154 thus creating a <em>C closure</em> |
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2155 (see <a href="#lua_pushcclosure"><code>lua_pushcclosure</code></a>); |
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2156 these values are called <em>upvalues</em> and are |
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2157 accessible to the function whenever it is called. |
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2158 |
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2159 |
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2160 <p> |
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2161 Whenever a C function is called, |
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2162 its upvalues are located at specific pseudo-indices. |
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2163 These pseudo-indices are produced by the macro |
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2164 <a href="#lua_upvalueindex"><code>lua_upvalueindex</code></a>. |
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2165 The first value associated with a function is at position |
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2166 <code>lua_upvalueindex(1)</code>, and so on. |
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2167 Any access to <code>lua_upvalueindex(<em>n</em>)</code>, |
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2168 where <em>n</em> is greater than the number of upvalues of the |
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2169 current function (but not greater than 256), |
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2170 produces an acceptable but invalid index. |
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2171 |
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2172 |
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2173 |
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2174 |
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2175 |
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2176 <h2>4.5 – <a name="4.5">Registry</a></h2> |
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2177 |
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2178 <p> |
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2179 Lua provides a <em>registry</em>, |
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2180 a predefined table that can be used by any C code to |
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2181 store whatever Lua values it needs to store. |
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2182 The registry table is always located at pseudo-index |
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2183 <a name="pdf-LUA_REGISTRYINDEX"><code>LUA_REGISTRYINDEX</code></a>, |
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2184 which is a valid index. |
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2185 Any C library can store data into this table, |
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2186 but it must take care to choose keys |
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2187 that are different from those used |
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2188 by other libraries, to avoid collisions. |
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2189 Typically, you should use as key a string containing your library name, |
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2190 or a light userdata with the address of a C object in your code, |
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2191 or any Lua object created by your code. |
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2192 As with variable names, |
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2193 string keys starting with an underscore followed by |
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2194 uppercase letters are reserved for Lua. |
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2195 |
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2196 |
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2197 <p> |
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2198 The integer keys in the registry are used |
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2199 by the reference mechanism (see <a href="#luaL_ref"><code>luaL_ref</code></a>) |
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2200 and by some predefined values. |
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2201 Therefore, integer keys must not be used for other purposes. |
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2202 |
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2203 |
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2204 <p> |
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2205 When you create a new Lua state, |
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2206 its registry comes with some predefined values. |
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2207 These predefined values are indexed with integer keys |
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2208 defined as constants in <code>lua.h</code>. |
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2209 The following constants are defined: |
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2210 |
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2211 <ul> |
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2212 <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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2213 the main thread of the state. |
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2214 (The main thread is the one created together with the state.) |
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2215 </li> |
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2216 |
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2217 <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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2218 the global environment. |
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2219 </li> |
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2220 </ul> |
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2221 |
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2222 |
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2223 |
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2224 |
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2225 <h2>4.6 – <a name="4.6">Error Handling in C</a></h2> |
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2226 |
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2227 <p> |
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2228 Internally, Lua uses the C <code>longjmp</code> facility to handle errors. |
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2229 (Lua will use exceptions if you compile it as C++; |
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2230 search for <code>LUAI_THROW</code> in the source code for details.) |
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2231 When Lua faces any error |
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2232 (such as a memory allocation error, type errors, syntax errors, |
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2233 and runtime errors) |
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2234 it <em>raises</em> an error; |
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2235 that is, it does a long jump. |
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2236 A <em>protected environment</em> uses <code>setjmp</code> |
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2237 to set a recovery point; |
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2238 any error jumps to the most recent active recovery point. |
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2239 |
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2240 |
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2241 <p> |
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2242 If an error happens outside any protected environment, |
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2243 Lua calls a <em>panic function</em> (see <a href="#lua_atpanic"><code>lua_atpanic</code></a>) |
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2244 and then calls <code>abort</code>, |
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2245 thus exiting the host application. |
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2246 Your panic function can avoid this exit by |
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2247 never returning |
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2248 (e.g., doing a long jump to your own recovery point outside Lua). |
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2249 |
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2250 |
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2251 <p> |
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2252 The panic function runs as if it were a message handler (see <a href="#2.3">§2.3</a>); |
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2253 in particular, the error message is at the top of the stack. |
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2254 However, there is no guarantee about stack space. |
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2255 To push anything on the stack, |
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2256 the panic function must first check the available space (see <a href="#4.2">§4.2</a>). |
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2257 |
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2258 |
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2259 <p> |
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2260 Most functions in the API can raise an error, |
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2261 for instance due to a memory allocation error. |
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2262 The documentation for each function indicates whether |
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2263 it can raise errors. |
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2264 |
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2265 |
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2266 <p> |
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2267 Inside a C function you can raise an error by calling <a href="#lua_error"><code>lua_error</code></a>. |
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2268 |
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2269 |
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2270 |
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2271 |
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2272 |
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2273 <h2>4.7 – <a name="4.7">Handling Yields in C</a></h2> |
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2274 |
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2275 <p> |
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2276 Internally, Lua uses the C <code>longjmp</code> facility to yield a coroutine. |
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2277 Therefore, if a C function <code>foo</code> calls an API function |
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2278 and this API function yields |
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2279 (directly or indirectly by calling another function that yields), |
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2280 Lua cannot return to <code>foo</code> any more, |
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2281 because the <code>longjmp</code> removes its frame from the C stack. |
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2282 |
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2283 |
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2284 <p> |
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2285 To avoid this kind of problem, |
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2286 Lua raises an error whenever it tries to yield across an API call, |
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2287 except for three functions: |
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2288 <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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2289 All those functions receive a <em>continuation function</em> |
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2290 (as a parameter named <code>k</code>) to continue execution after a yield. |
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2291 |
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2292 |
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2293 <p> |
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2294 We need to set some terminology to explain continuations. |
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2295 We have a C function called from Lua which we will call |
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2296 the <em>original function</em>. |
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2297 This original function then calls one of those three functions in the C API, |
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2298 which we will call the <em>callee function</em>, |
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2299 that then yields the current thread. |
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2300 (This can happen when the callee function is <a href="#lua_yieldk"><code>lua_yieldk</code></a>, |
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2301 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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2302 and the function called by them yields.) |
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2303 |
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2304 |
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2305 <p> |
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2306 Suppose the running thread yields while executing the callee function. |
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2307 After the thread resumes, |
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2308 it eventually will finish running the callee function. |
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2309 However, |
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2310 the callee function cannot return to the original function, |
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2311 because its frame in the C stack was destroyed by the yield. |
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2312 Instead, Lua calls a <em>continuation function</em>, |
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2313 which was given as an argument to the callee function. |
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2314 As the name implies, |
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2315 the continuation function should continue the task |
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2316 of the original function. |
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2317 |
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2318 |
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2319 <p> |
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2320 As an illustration, consider the following function: |
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2321 |
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2322 <pre> |
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2323 int original_function (lua_State *L) { |
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2324 ... /* code 1 */ |
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2325 status = lua_pcall(L, n, m, h); /* calls Lua */ |
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2326 ... /* code 2 */ |
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2327 } |
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2328 </pre><p> |
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2329 Now we want to allow |
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2330 the Lua code being run by <a href="#lua_pcall"><code>lua_pcall</code></a> to yield. |
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2331 First, we can rewrite our function like here: |
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2332 |
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2333 <pre> |
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2334 int k (lua_State *L, int status, lua_KContext ctx) { |
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2335 ... /* code 2 */ |
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2336 } |
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2337 |
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2338 int original_function (lua_State *L) { |
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2339 ... /* code 1 */ |
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2340 return k(L, lua_pcall(L, n, m, h), ctx); |
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2341 } |
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2342 </pre><p> |
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2343 In the above code, |
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2344 the new function <code>k</code> is a |
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2345 <em>continuation function</em> (with type <a href="#lua_KFunction"><code>lua_KFunction</code></a>), |
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2346 which should do all the work that the original function |
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2347 was doing after calling <a href="#lua_pcall"><code>lua_pcall</code></a>. |
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2348 Now, we must inform Lua that it must call <code>k</code> if the Lua code |
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2349 being executed by <a href="#lua_pcall"><code>lua_pcall</code></a> gets interrupted in some way |
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2350 (errors or yielding), |
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2351 so we rewrite the code as here, |
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2352 replacing <a href="#lua_pcall"><code>lua_pcall</code></a> by <a href="#lua_pcallk"><code>lua_pcallk</code></a>: |
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2353 |
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2354 <pre> |
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2355 int original_function (lua_State *L) { |
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2356 ... /* code 1 */ |
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2357 return k(L, lua_pcallk(L, n, m, h, ctx2, k), ctx1); |
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2358 } |
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2359 </pre><p> |
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2360 Note the external, explicit call to the continuation: |
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2361 Lua will call the continuation only if needed, that is, |
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2362 in case of errors or resuming after a yield. |
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2363 If the called function returns normally without ever yielding, |
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2364 <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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2365 (Of course, instead of calling the continuation in that case, |
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2366 you can do the equivalent work directly inside the original function.) |
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2367 |
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2368 |
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2369 <p> |
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2370 Besides the Lua state, |
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2371 the continuation function has two other parameters: |
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2372 the final status of the call plus the context value (<code>ctx</code>) that |
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2373 was passed originally to <a href="#lua_pcallk"><code>lua_pcallk</code></a>. |
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2374 (Lua does not use this context value; |
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2375 it only passes this value from the original function to the |
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2376 continuation function.) |
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2377 For <a href="#lua_pcallk"><code>lua_pcallk</code></a>, |
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2378 the status is the same value that would be returned by <a href="#lua_pcallk"><code>lua_pcallk</code></a>, |
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2379 except that it is <a href="#pdf-LUA_YIELD"><code>LUA_YIELD</code></a> when being executed after a yield |
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2380 (instead of <a href="#pdf-LUA_OK"><code>LUA_OK</code></a>). |
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2381 For <a href="#lua_yieldk"><code>lua_yieldk</code></a> and <a href="#lua_callk"><code>lua_callk</code></a>, |
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2382 the status is always <a href="#pdf-LUA_YIELD"><code>LUA_YIELD</code></a> when Lua calls the continuation. |
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2383 (For these two functions, |
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2384 Lua will not call the continuation in case of errors, |
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2385 because they do not handle errors.) |
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2386 Similarly, when using <a href="#lua_callk"><code>lua_callk</code></a>, |
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2387 you should call the continuation function |
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2388 with <a href="#pdf-LUA_OK"><code>LUA_OK</code></a> as the status. |
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2389 (For <a href="#lua_yieldk"><code>lua_yieldk</code></a>, there is not much point in calling |
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2390 directly the continuation function, |
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2391 because <a href="#lua_yieldk"><code>lua_yieldk</code></a> usually does not return.) |
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2392 |
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2393 |
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2394 <p> |
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2395 Lua treats the continuation function as if it were the original function. |
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2396 The continuation function receives the same Lua stack |
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2397 from the original function, |
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2398 in the same state it would be if the callee function had returned. |
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2399 (For instance, |
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2400 after a <a href="#lua_callk"><code>lua_callk</code></a> the function and its arguments are |
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2401 removed from the stack and replaced by the results from the call.) |
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2402 It also has the same upvalues. |
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2403 Whatever it returns is handled by Lua as if it were the return |
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2404 of the original function. |
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2405 |
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2406 |
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2407 |
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2408 |
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2409 |
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2410 <h2>4.8 – <a name="4.8">Functions and Types</a></h2> |
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2411 |
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2412 <p> |
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2413 Here we list all functions and types from the C API in |
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2414 alphabetical order. |
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2415 Each function has an indicator like this: |
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2416 <span class="apii">[-o, +p, <em>x</em>]</span> |
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2417 |
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2418 |
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2419 <p> |
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2420 The first field, <code>o</code>, |
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2421 is how many elements the function pops from the stack. |
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2422 The second field, <code>p</code>, |
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2423 is how many elements the function pushes onto the stack. |
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2424 (Any function always pushes its results after popping its arguments.) |
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2425 A field in the form <code>x|y</code> means the function can push (or pop) |
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2426 <code>x</code> or <code>y</code> elements, |
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2427 depending on the situation; |
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2428 an interrogation mark '<code>?</code>' means that |
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2429 we cannot know how many elements the function pops/pushes |
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2430 by looking only at its arguments |
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2431 (e.g., they may depend on what is on the stack). |
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2432 The third field, <code>x</code>, |
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2433 tells whether the function may raise errors: |
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2434 '<code>-</code>' means the function never raises any error; |
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2435 '<code>e</code>' means the function may raise errors; |
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2436 '<code>v</code>' means the function may raise an error on purpose. |
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2437 |
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2438 |
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2439 |
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2440 <hr><h3><a name="lua_absindex"><code>lua_absindex</code></a></h3><p> |
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2441 <span class="apii">[-0, +0, –]</span> |
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2442 <pre>int lua_absindex (lua_State *L, int idx);</pre> |
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2443 |
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2444 <p> |
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2445 Converts the acceptable index <code>idx</code> into an absolute index |
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2446 (that is, one that does not depend on the stack top). |
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2447 |
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2448 |
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2449 |
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2450 |
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2451 |
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2452 <hr><h3><a name="lua_Alloc"><code>lua_Alloc</code></a></h3> |
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2453 <pre>typedef void * (*lua_Alloc) (void *ud, |
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2454 void *ptr, |
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2455 size_t osize, |
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2456 size_t nsize);</pre> |
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2457 |
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2458 <p> |
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2459 The type of the memory-allocation function used by Lua states. |
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2460 The allocator function must provide a |
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2461 functionality similar to <code>realloc</code>, |
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2462 but not exactly the same. |
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2463 Its arguments are |
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2464 <code>ud</code>, an opaque pointer passed to <a href="#lua_newstate"><code>lua_newstate</code></a>; |
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2465 <code>ptr</code>, a pointer to the block being allocated/reallocated/freed; |
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2466 <code>osize</code>, the original size of the block or some code about what |
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2467 is being allocated; |
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2468 and <code>nsize</code>, the new size of the block. |
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2469 |
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2470 |
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2471 <p> |
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2472 When <code>ptr</code> is not <code>NULL</code>, |
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2473 <code>osize</code> is the size of the block pointed by <code>ptr</code>, |
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2474 that is, the size given when it was allocated or reallocated. |
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2475 |
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2476 |
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2477 <p> |
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2478 When <code>ptr</code> is <code>NULL</code>, |
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2479 <code>osize</code> encodes the kind of object that Lua is allocating. |
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2480 <code>osize</code> is any of |
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2481 <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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2482 <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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2483 Lua is creating a new object of that type. |
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2484 When <code>osize</code> is some other value, |
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2485 Lua is allocating memory for something else. |
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2486 |
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2487 |
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2488 <p> |
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2489 Lua assumes the following behavior from the allocator function: |
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2490 |
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2491 |
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2492 <p> |
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2493 When <code>nsize</code> is zero, |
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2494 the allocator must behave like <code>free</code> |
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2495 and return <code>NULL</code>. |
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2496 |
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2497 |
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2498 <p> |
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2499 When <code>nsize</code> is not zero, |
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2500 the allocator must behave like <code>realloc</code>. |
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2501 The allocator returns <code>NULL</code> |
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2502 if and only if it cannot fulfill the request. |
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2503 Lua assumes that the allocator never fails when |
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2504 <code>osize >= nsize</code>. |
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2505 |
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2506 |
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2507 <p> |
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2508 Here is a simple implementation for the allocator function. |
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2509 It is used in the auxiliary library by <a href="#luaL_newstate"><code>luaL_newstate</code></a>. |
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2510 |
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2511 <pre> |
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2512 static void *l_alloc (void *ud, void *ptr, size_t osize, |
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2513 size_t nsize) { |
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2514 (void)ud; (void)osize; /* not used */ |
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2515 if (nsize == 0) { |
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2516 free(ptr); |
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2517 return NULL; |
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2518 } |
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2519 else |
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2520 return realloc(ptr, nsize); |
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2521 } |
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2522 </pre><p> |
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2523 Note that Standard C ensures |
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2524 that <code>free(NULL)</code> has no effect and that |
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2525 <code>realloc(NULL,size)</code> is equivalent to <code>malloc(size)</code>. |
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2526 This code assumes that <code>realloc</code> does not fail when shrinking a block. |
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2527 (Although Standard C does not ensure this behavior, |
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2528 it seems to be a safe assumption.) |
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2529 |
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2530 |
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2531 |
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2532 |
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2533 |
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2534 <hr><h3><a name="lua_arith"><code>lua_arith</code></a></h3><p> |
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2535 <span class="apii">[-(2|1), +1, <em>e</em>]</span> |
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2536 <pre>void lua_arith (lua_State *L, int op);</pre> |
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2537 |
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2538 <p> |
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2539 Performs an arithmetic or bitwise operation over the two values |
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2540 (or one, in the case of negations) |
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2541 at the top of the stack, |
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2542 with the value at the top being the second operand, |
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2543 pops these values, and pushes the result of the operation. |
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2544 The function follows the semantics of the corresponding Lua operator |
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2545 (that is, it may call metamethods). |
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2546 |
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2547 |
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2548 <p> |
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2549 The value of <code>op</code> must be one of the following constants: |
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2550 |
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2551 <ul> |
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2552 |
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2553 <li><b><a name="pdf-LUA_OPADD"><code>LUA_OPADD</code></a>: </b> performs addition (<code>+</code>)</li> |
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2554 <li><b><a name="pdf-LUA_OPSUB"><code>LUA_OPSUB</code></a>: </b> performs subtraction (<code>-</code>)</li> |
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2555 <li><b><a name="pdf-LUA_OPMUL"><code>LUA_OPMUL</code></a>: </b> performs multiplication (<code>*</code>)</li> |
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2556 <li><b><a name="pdf-LUA_OPDIV"><code>LUA_OPDIV</code></a>: </b> performs float division (<code>/</code>)</li> |
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2557 <li><b><a name="pdf-LUA_OPIDIV"><code>LUA_OPIDIV</code></a>: </b> performs floor division (<code>//</code>)</li> |
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2558 <li><b><a name="pdf-LUA_OPMOD"><code>LUA_OPMOD</code></a>: </b> performs modulo (<code>%</code>)</li> |
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2559 <li><b><a name="pdf-LUA_OPPOW"><code>LUA_OPPOW</code></a>: </b> performs exponentiation (<code>^</code>)</li> |
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2560 <li><b><a name="pdf-LUA_OPUNM"><code>LUA_OPUNM</code></a>: </b> performs mathematical negation (unary <code>-</code>)</li> |
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2561 <li><b><a name="pdf-LUA_OPBNOT"><code>LUA_OPBNOT</code></a>: </b> performs bitwise negation (<code>~</code>)</li> |
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2562 <li><b><a name="pdf-LUA_OPBAND"><code>LUA_OPBAND</code></a>: </b> performs bitwise and (<code>&</code>)</li> |
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2563 <li><b><a name="pdf-LUA_OPBOR"><code>LUA_OPBOR</code></a>: </b> performs bitwise or (<code>|</code>)</li> |
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2564 <li><b><a name="pdf-LUA_OPBXOR"><code>LUA_OPBXOR</code></a>: </b> performs bitwise exclusive or (<code>~</code>)</li> |
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2565 <li><b><a name="pdf-LUA_OPSHL"><code>LUA_OPSHL</code></a>: </b> performs left shift (<code><<</code>)</li> |
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2566 <li><b><a name="pdf-LUA_OPSHR"><code>LUA_OPSHR</code></a>: </b> performs right shift (<code>>></code>)</li> |
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2567 |
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2568 </ul> |
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2569 |
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2570 |
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2571 |
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2572 |
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2573 <hr><h3><a name="lua_atpanic"><code>lua_atpanic</code></a></h3><p> |
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2574 <span class="apii">[-0, +0, –]</span> |
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2575 <pre>lua_CFunction lua_atpanic (lua_State *L, lua_CFunction panicf);</pre> |
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2576 |
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2577 <p> |
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2578 Sets a new panic function and returns the old one (see <a href="#4.6">§4.6</a>). |
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2579 |
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2580 |
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2581 |
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2582 |
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2583 |
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2584 <hr><h3><a name="lua_call"><code>lua_call</code></a></h3><p> |
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2585 <span class="apii">[-(nargs+1), +nresults, <em>e</em>]</span> |
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2586 <pre>void lua_call (lua_State *L, int nargs, int nresults);</pre> |
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2587 |
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2588 <p> |
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2589 Calls a function. |
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2590 |
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2591 |
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2592 <p> |
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2593 To call a function you must use the following protocol: |
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2594 first, the function to be called is pushed onto the stack; |
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2595 then, the arguments to the function are pushed |
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2596 in direct order; |
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2597 that is, the first argument is pushed first. |
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2598 Finally you call <a href="#lua_call"><code>lua_call</code></a>; |
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2599 <code>nargs</code> is the number of arguments that you pushed onto the stack. |
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2600 All arguments and the function value are popped from the stack |
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2601 when the function is called. |
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2602 The function results are pushed onto the stack when the function returns. |
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2603 The number of results is adjusted to <code>nresults</code>, |
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2604 unless <code>nresults</code> is <a name="pdf-LUA_MULTRET"><code>LUA_MULTRET</code></a>. |
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2605 In this case, all results from the function are pushed. |
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2606 Lua takes care that the returned values fit into the stack space. |
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2607 The function results are pushed onto the stack in direct order |
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2608 (the first result is pushed first), |
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2609 so that after the call the last result is on the top of the stack. |
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2610 |
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2611 |
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2612 <p> |
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2613 Any error inside the called function is propagated upwards |
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2614 (with a <code>longjmp</code>). |
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2615 |
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2616 |
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2617 <p> |
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2618 The following example shows how the host program can do the |
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2619 equivalent to this Lua code: |
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2620 |
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2621 <pre> |
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2622 a = f("how", t.x, 14) |
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2623 </pre><p> |
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2624 Here it is in C: |
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2625 |
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2626 <pre> |
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2627 lua_getglobal(L, "f"); /* function to be called */ |
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2628 lua_pushliteral(L, "how"); /* 1st argument */ |
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2629 lua_getglobal(L, "t"); /* table to be indexed */ |
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2630 lua_getfield(L, -1, "x"); /* push result of t.x (2nd arg) */ |
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2631 lua_remove(L, -2); /* remove 't' from the stack */ |
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2632 lua_pushinteger(L, 14); /* 3rd argument */ |
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2633 lua_call(L, 3, 1); /* call 'f' with 3 arguments and 1 result */ |
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2634 lua_setglobal(L, "a"); /* set global 'a' */ |
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2635 </pre><p> |
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2636 Note that the code above is <em>balanced</em>: |
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2637 at its end, the stack is back to its original configuration. |
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2638 This is considered good programming practice. |
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2639 |
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2640 |
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2641 |
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2642 |
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2643 |
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2644 <hr><h3><a name="lua_callk"><code>lua_callk</code></a></h3><p> |
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2645 <span class="apii">[-(nargs + 1), +nresults, <em>e</em>]</span> |
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2646 <pre>void lua_callk (lua_State *L, |
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2647 int nargs, |
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2648 int nresults, |
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2649 lua_KContext ctx, |
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|
2650 lua_KFunction k);</pre> |
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2651 |
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2652 <p> |
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2653 This function behaves exactly like <a href="#lua_call"><code>lua_call</code></a>, |
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2654 but allows the called function to yield (see <a href="#4.7">§4.7</a>). |
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2655 |
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2656 |
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2657 |
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2658 |
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2659 |
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2660 <hr><h3><a name="lua_CFunction"><code>lua_CFunction</code></a></h3> |
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2661 <pre>typedef int (*lua_CFunction) (lua_State *L);</pre> |
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2662 |
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2663 <p> |
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2664 Type for C functions. |
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|
2665 |
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2666 |
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2667 <p> |
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2668 In order to communicate properly with Lua, |
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2669 a C function must use the following protocol, |
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2670 which defines the way parameters and results are passed: |
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2671 a C function receives its arguments from Lua in its stack |
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2672 in direct order (the first argument is pushed first). |
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2673 So, when the function starts, |
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2674 <code>lua_gettop(L)</code> returns the number of arguments received by the function. |
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2675 The first argument (if any) is at index 1 |
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2676 and its last argument is at index <code>lua_gettop(L)</code>. |
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2677 To return values to Lua, a C function just pushes them onto the stack, |
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2678 in direct order (the first result is pushed first), |
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2679 and returns the number of results. |
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2680 Any other value in the stack below the results will be properly |
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2681 discarded by Lua. |
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2682 Like a Lua function, a C function called by Lua can also return |
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2683 many results. |
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|
2684 |
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|
2685 |
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|
2686 <p> |
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|
2687 As an example, the following function receives a variable number |
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2688 of numerical arguments and returns their average and their sum: |
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|
2689 |
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|
2690 <pre> |
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|
2691 static int foo (lua_State *L) { |
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2692 int n = lua_gettop(L); /* number of arguments */ |
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2693 lua_Number sum = 0.0; |
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2694 int i; |
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2695 for (i = 1; i <= n; i++) { |
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2696 if (!lua_isnumber(L, i)) { |
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2697 lua_pushliteral(L, "incorrect argument"); |
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2698 lua_error(L); |
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|
2699 } |
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2700 sum += lua_tonumber(L, i); |
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2701 } |
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2702 lua_pushnumber(L, sum/n); /* first result */ |
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2703 lua_pushnumber(L, sum); /* second result */ |
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2704 return 2; /* number of results */ |
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2705 } |
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|
2706 </pre> |
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2707 |
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2708 |
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2709 |
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2710 |
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|
2711 <hr><h3><a name="lua_checkstack"><code>lua_checkstack</code></a></h3><p> |
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2712 <span class="apii">[-0, +0, –]</span> |
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2713 <pre>int lua_checkstack (lua_State *L, int n);</pre> |
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2714 |
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2715 <p> |
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2716 Ensures that the stack has space for at least <code>n</code> extra slots. |
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2717 It returns false if it cannot fulfill the request, |
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2718 either because it would cause the stack |
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2719 to be larger than a fixed maximum size |
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2720 (typically at least several thousand elements) or |
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2721 because it cannot allocate memory for the extra space. |
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2722 This function never shrinks the stack; |
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2723 if the stack is already larger than the new size, |
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2724 it is left unchanged. |
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2725 |
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2726 |
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2727 |
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2728 |
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2729 |
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2730 <hr><h3><a name="lua_close"><code>lua_close</code></a></h3><p> |
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2731 <span class="apii">[-0, +0, –]</span> |
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2732 <pre>void lua_close (lua_State *L);</pre> |
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2733 |
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2734 <p> |
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2735 Destroys all objects in the given Lua state |
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2736 (calling the corresponding garbage-collection metamethods, if any) |
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2737 and frees all dynamic memory used by this state. |
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2738 On several platforms, you may not need to call this function, |
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2739 because all resources are naturally released when the host program ends. |
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2740 On the other hand, long-running programs that create multiple states, |
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2741 such as daemons or web servers, |
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2742 will probably need to close states as soon as they are not needed. |
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2743 |
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2744 |
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2745 |
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2746 |
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2747 |
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2748 <hr><h3><a name="lua_compare"><code>lua_compare</code></a></h3><p> |
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2749 <span class="apii">[-0, +0, <em>e</em>]</span> |
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2750 <pre>int lua_compare (lua_State *L, int index1, int index2, int op);</pre> |
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2751 |
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2752 <p> |
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2753 Compares two Lua values. |
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2754 Returns 1 if the value at index <code>index1</code> satisfies <code>op</code> |
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2755 when compared with the value at index <code>index2</code>, |
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2756 following the semantics of the corresponding Lua operator |
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2757 (that is, it may call metamethods). |
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2758 Otherwise returns 0. |
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2759 Also returns 0 if any of the indices is not valid. |
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2760 |
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2761 |
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2762 <p> |
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2763 The value of <code>op</code> must be one of the following constants: |
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2764 |
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2765 <ul> |
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2766 |
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2767 <li><b><a name="pdf-LUA_OPEQ"><code>LUA_OPEQ</code></a>: </b> compares for equality (<code>==</code>)</li> |
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2768 <li><b><a name="pdf-LUA_OPLT"><code>LUA_OPLT</code></a>: </b> compares for less than (<code><</code>)</li> |
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2769 <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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2770 |
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2771 </ul> |
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2772 |
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2773 |
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2774 |
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2775 |
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2776 <hr><h3><a name="lua_concat"><code>lua_concat</code></a></h3><p> |
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2777 <span class="apii">[-n, +1, <em>e</em>]</span> |
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2778 <pre>void lua_concat (lua_State *L, int n);</pre> |
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2779 |
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2780 <p> |
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2781 Concatenates the <code>n</code> values at the top of the stack, |
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2782 pops them, and leaves the result at the top. |
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2783 If <code>n</code> is 1, the result is the single value on the stack |
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2784 (that is, the function does nothing); |
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2785 if <code>n</code> is 0, the result is the empty string. |
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2786 Concatenation is performed following the usual semantics of Lua |
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2787 (see <a href="#3.4.6">§3.4.6</a>). |
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2788 |
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2789 |
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2790 |
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2791 |
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2792 |
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2793 <hr><h3><a name="lua_copy"><code>lua_copy</code></a></h3><p> |
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2794 <span class="apii">[-0, +0, –]</span> |
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2795 <pre>void lua_copy (lua_State *L, int fromidx, int toidx);</pre> |
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2796 |
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2797 <p> |
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2798 Copies the element at index <code>fromidx</code> |
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2799 into the valid index <code>toidx</code>, |
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2800 replacing the value at that position. |
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2801 Values at other positions are not affected. |
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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 |
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2807 <hr><h3><a name="lua_createtable"><code>lua_createtable</code></a></h3><p> |
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2808 <span class="apii">[-0, +1, <em>e</em>]</span> |
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2809 <pre>void lua_createtable (lua_State *L, int narr, int nrec);</pre> |
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2810 |
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2811 <p> |
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2812 Creates a new empty table and pushes it onto the stack. |
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2813 Parameter <code>narr</code> is a hint for how many elements the table |
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2814 will have as a sequence; |
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2815 parameter <code>nrec</code> is a hint for how many other elements |
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2816 the table will have. |
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2817 Lua may use these hints to preallocate memory for the new table. |
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2818 This pre-allocation is useful for performance when you know in advance |
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2819 how many elements the table will have. |
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2820 Otherwise you can use the function <a href="#lua_newtable"><code>lua_newtable</code></a>. |
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2821 |
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2822 |
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2823 |
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2824 |
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2825 |
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2826 <hr><h3><a name="lua_dump"><code>lua_dump</code></a></h3><p> |
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2827 <span class="apii">[-0, +0, <em>e</em>]</span> |
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2828 <pre>int lua_dump (lua_State *L, |
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2829 lua_Writer writer, |
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2830 void *data, |
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2831 int strip);</pre> |
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2832 |
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2833 <p> |
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2834 Dumps a function as a binary chunk. |
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2835 Receives a Lua function on the top of the stack |
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2836 and produces a binary chunk that, |
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2837 if loaded again, |
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2838 results in a function equivalent to the one dumped. |
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2839 As it produces parts of the chunk, |
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2840 <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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2841 with the given <code>data</code> |
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2842 to write them. |
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2843 |
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2844 |
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2845 <p> |
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2846 If <code>strip</code> is true, |
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2847 the binary representation is created without debug information |
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2848 about the function. |
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|
2849 |
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|
2850 |
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2851 <p> |
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2852 The value returned is the error code returned by the last |
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2853 call to the writer; |
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2854 0 means no errors. |
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2855 |
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2856 |
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2857 <p> |
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2858 This function does not pop the Lua function from the stack. |
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2859 |
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|
2860 |
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|
2861 |
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|
2862 |
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2863 |
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2864 <hr><h3><a name="lua_error"><code>lua_error</code></a></h3><p> |
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2865 <span class="apii">[-1, +0, <em>v</em>]</span> |
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2866 <pre>int lua_error (lua_State *L);</pre> |
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2867 |
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2868 <p> |
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2869 Generates a Lua error, |
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2870 using the value at the top of the stack as the error object. |
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2871 This function does a long jump, |
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2872 and therefore never returns |
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2873 (see <a href="#luaL_error"><code>luaL_error</code></a>). |
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2874 |
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|
2875 |
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2876 |
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|
2877 |
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2878 |
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2879 <hr><h3><a name="lua_gc"><code>lua_gc</code></a></h3><p> |
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2880 <span class="apii">[-0, +0, <em>e</em>]</span> |
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|
2881 <pre>int lua_gc (lua_State *L, int what, int data);</pre> |
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|
2882 |
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|
2883 <p> |
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2884 Controls the garbage collector. |
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|
2885 |
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|
2886 |
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|
2887 <p> |
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|
2888 This function performs several tasks, |
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2889 according to the value of the parameter <code>what</code>: |
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|
2890 |
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|
2891 <ul> |
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|
2892 |
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|
2893 <li><b><code>LUA_GCSTOP</code>: </b> |
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2894 stops the garbage collector. |
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|
2895 </li> |
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|
2896 |
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|
2897 <li><b><code>LUA_GCRESTART</code>: </b> |
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2898 restarts the garbage collector. |
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|
2899 </li> |
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|
2900 |
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2901 <li><b><code>LUA_GCCOLLECT</code>: </b> |
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2902 performs a full garbage-collection cycle. |
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|
2903 </li> |
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|
2904 |
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|
2905 <li><b><code>LUA_GCCOUNT</code>: </b> |
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|
2906 returns the current amount of memory (in Kbytes) in use by Lua. |
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|
2907 </li> |
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|
2908 |
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|
2909 <li><b><code>LUA_GCCOUNTB</code>: </b> |
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2910 returns the remainder of dividing the current amount of bytes of |
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2911 memory in use by Lua by 1024. |
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2912 </li> |
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|
2913 |
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2914 <li><b><code>LUA_GCSTEP</code>: </b> |
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|
2915 performs an incremental step of garbage collection. |
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|
2916 </li> |
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|
2917 |
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|
2918 <li><b><code>LUA_GCSETPAUSE</code>: </b> |
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2919 sets <code>data</code> as the new value |
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|
2920 for the <em>pause</em> of the collector (see <a href="#2.5">§2.5</a>) |
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2921 and returns the previous value of the pause. |
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|
2922 </li> |
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|
2923 |
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|
2924 <li><b><code>LUA_GCSETSTEPMUL</code>: </b> |
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2925 sets <code>data</code> as the new value for the <em>step multiplier</em> of |
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2926 the collector (see <a href="#2.5">§2.5</a>) |
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|
2927 and returns the previous value of the step multiplier. |
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|
2928 </li> |
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|
2929 |
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|
2930 <li><b><code>LUA_GCISRUNNING</code>: </b> |
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|
2931 returns a boolean that tells whether the collector is running |
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|
2932 (i.e., not stopped). |
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|
2933 </li> |
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|
2934 |
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|
2935 </ul> |
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|
2936 |
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|
2937 <p> |
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|
2938 For more details about these options, |
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2939 see <a href="#pdf-collectgarbage"><code>collectgarbage</code></a>. |
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|
2940 |
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|
2941 |
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|
2942 |
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|
2943 |
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|
2944 |
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|
2945 <hr><h3><a name="lua_getallocf"><code>lua_getallocf</code></a></h3><p> |
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2946 <span class="apii">[-0, +0, –]</span> |
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|
2947 <pre>lua_Alloc lua_getallocf (lua_State *L, void **ud);</pre> |
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2948 |
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|
2949 <p> |
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|
2950 Returns the memory-allocation function of a given state. |
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|
2951 If <code>ud</code> is not <code>NULL</code>, Lua stores in <code>*ud</code> the |
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2952 opaque pointer given when the memory-allocator function was set. |
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|
2953 |
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|
2954 |
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|
2955 |
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|
2956 |
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2957 |
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2958 <hr><h3><a name="lua_getfield"><code>lua_getfield</code></a></h3><p> |
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2959 <span class="apii">[-0, +1, <em>e</em>]</span> |
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|
2960 <pre>int lua_getfield (lua_State *L, int index, const char *k);</pre> |
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2961 |
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2962 <p> |
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2963 Pushes onto the stack the value <code>t[k]</code>, |
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2964 where <code>t</code> is the value at the given index. |
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2965 As in Lua, this function may trigger a metamethod |
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2966 for the "index" event (see <a href="#2.4">§2.4</a>). |
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2967 |
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2968 |
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2969 <p> |
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|
2970 Returns the type of the pushed value. |
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2971 |
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2972 |
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2973 |
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2974 |
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2975 |
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2976 <hr><h3><a name="lua_getextraspace"><code>lua_getextraspace</code></a></h3><p> |
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2977 <span class="apii">[-0, +0, –]</span> |
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2978 <pre>void *lua_getextraspace (lua_State *L);</pre> |
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2979 |
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2980 <p> |
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2981 Returns a pointer to a raw memory area associated with the |
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2982 given Lua state. |
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2983 The application can use this area for any purpose; |
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2984 Lua does not use it for anything. |
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2985 |
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2986 |
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2987 <p> |
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2988 Each new thread has this area initialized with a copy |
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2989 of the area of the main thread. |
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|
2990 |
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|
2991 |
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2992 <p> |
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2993 By default, this area has the size of a pointer to void, |
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2994 but you can recompile Lua with a different size for this area. |
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2995 (See <code>LUA_EXTRASPACE</code> in <code>luaconf.h</code>.) |
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2996 |
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|
2997 |
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2998 |
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2999 |
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3000 |
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3001 <hr><h3><a name="lua_getglobal"><code>lua_getglobal</code></a></h3><p> |
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3002 <span class="apii">[-0, +1, <em>e</em>]</span> |
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3003 <pre>int lua_getglobal (lua_State *L, const char *name);</pre> |
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3004 |
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3005 <p> |
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3006 Pushes onto the stack the value of the global <code>name</code>. |
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3007 Returns the type of that value. |
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|
3008 |
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|
3009 |
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|
3010 |
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|
3011 |
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|
3012 |
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|
3013 <hr><h3><a name="lua_geti"><code>lua_geti</code></a></h3><p> |
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3014 <span class="apii">[-0, +1, <em>e</em>]</span> |
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|
3015 <pre>int lua_geti (lua_State *L, int index, lua_Integer i);</pre> |
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|
3016 |
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|
3017 <p> |
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|
3018 Pushes onto the stack the value <code>t[i]</code>, |
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3019 where <code>t</code> is the value at the given index. |
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3020 As in Lua, this function may trigger a metamethod |
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|
3021 for the "index" event (see <a href="#2.4">§2.4</a>). |
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|
3022 |
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|
3023 |
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|
3024 <p> |
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|
3025 Returns the type of the pushed value. |
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|
3026 |
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diff
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|
3027 |
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diff
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|
3028 |
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diff
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|
3029 |
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|
3030 |
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3031 <hr><h3><a name="lua_getmetatable"><code>lua_getmetatable</code></a></h3><p> |
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3032 <span class="apii">[-0, +(0|1), –]</span> |
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|
3033 <pre>int lua_getmetatable (lua_State *L, int index);</pre> |
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|
3034 |
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3035 <p> |
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3036 If the value at the given index has a metatable, |
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3037 the function pushes that metatable onto the stack and returns 1. |
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3038 Otherwise, |
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|
3039 the function returns 0 and pushes nothing on the stack. |
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|
3040 |
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|
3041 |
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|
3042 |
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diff
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|
3043 |
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|
3044 |
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|
3045 <hr><h3><a name="lua_gettable"><code>lua_gettable</code></a></h3><p> |
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|
3046 <span class="apii">[-1, +1, <em>e</em>]</span> |
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|
3047 <pre>int lua_gettable (lua_State *L, int index);</pre> |
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|
3048 |
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|
3049 <p> |
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|
3050 Pushes onto the stack the value <code>t[k]</code>, |
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|
3051 where <code>t</code> is the value at the given index |
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|
3052 and <code>k</code> is the value at the top of the stack. |
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|
3053 |
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|
3054 |
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|
3055 <p> |
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|
3056 This function pops the key from the stack, |
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|
3057 pushing the resulting value in its place. |
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|
3058 As in Lua, this function may trigger a metamethod |
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|
3059 for the "index" event (see <a href="#2.4">§2.4</a>). |
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|
3060 |
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diff
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|
3061 |
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|
3062 <p> |
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|
3063 Returns the type of the pushed value. |
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|
3064 |
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|
3065 |
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|
3066 |
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|
3067 |
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|
3068 |
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|
3069 <hr><h3><a name="lua_gettop"><code>lua_gettop</code></a></h3><p> |
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3070 <span class="apii">[-0, +0, –]</span> |
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|
3071 <pre>int lua_gettop (lua_State *L);</pre> |
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|
3072 |
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|
3073 <p> |
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|
3074 Returns the index of the top element in the stack. |
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|
3075 Because indices start at 1, |
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|
3076 this result is equal to the number of elements in the stack; |
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|
3077 in particular, 0 means an empty stack. |
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|
3078 |
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|
3079 |
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|
3080 |
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|
3081 |
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|
3082 |
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|
3083 <hr><h3><a name="lua_getuservalue"><code>lua_getuservalue</code></a></h3><p> |
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3084 <span class="apii">[-0, +1, –]</span> |
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|
3085 <pre>int lua_getuservalue (lua_State *L, int index);</pre> |
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3086 |
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3087 <p> |
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3088 Pushes onto the stack the Lua value associated with the userdata |
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|
3089 at the given index. |
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|
3090 |
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|
3091 |
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3092 <p> |
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3093 Returns the type of the pushed value. |
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changeset
|
3094 |
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|
3095 |
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diff
changeset
|
3096 |
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diff
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|
3097 |
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diff
changeset
|
3098 |
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3099 <hr><h3><a name="lua_insert"><code>lua_insert</code></a></h3><p> |
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3100 <span class="apii">[-1, +1, –]</span> |
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|
3101 <pre>void lua_insert (lua_State *L, int index);</pre> |
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|
3102 |
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|
3103 <p> |
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3104 Moves the top element into the given valid index, |
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|
3105 shifting up the elements above this index to open space. |
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3106 This function cannot be called with a pseudo-index, |
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3107 because a pseudo-index is not an actual stack position. |
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|
3108 |
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diff
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|
3109 |
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diff
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|
3110 |
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|
3111 |
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diff
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|
3112 |
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3113 <hr><h3><a name="lua_Integer"><code>lua_Integer</code></a></h3> |
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3114 <pre>typedef ... lua_Integer;</pre> |
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3115 |
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3116 <p> |
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3117 The type of integers in Lua. |
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|
3118 |
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|
3119 |
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3120 <p> |
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3121 By default this type is <code>long long</code>, |
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3122 (usually a 64-bit two-complement integer), |
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|
3123 but that can be changed to <code>long</code> or <code>int</code> |
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3124 (usually a 32-bit two-complement integer). |
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3125 (See <code>LUA_INT</code> in <code>luaconf.h</code>.) |
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|
3126 |
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|
3127 |
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3128 <p> |
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|
3129 Lua also defines the constants |
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|
3130 <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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|
3131 with the minimum and the maximum values that fit in this type. |
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|
3132 |
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|
3133 |
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diff
changeset
|
3134 |
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diff
changeset
|
3135 |
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diff
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|
3136 |
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|
3137 <hr><h3><a name="lua_isboolean"><code>lua_isboolean</code></a></h3><p> |
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|
3138 <span class="apii">[-0, +0, –]</span> |
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|
3139 <pre>int lua_isboolean (lua_State *L, int index);</pre> |
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|
3140 |
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|
3141 <p> |
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|
3142 Returns 1 if the value at the given index is a boolean, |
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|
3143 and 0 otherwise. |
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|
3144 |
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diff
changeset
|
3145 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
3146 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
3147 |
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diff
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|
3148 |
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|
3149 <hr><h3><a name="lua_iscfunction"><code>lua_iscfunction</code></a></h3><p> |
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|
3150 <span class="apii">[-0, +0, –]</span> |
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|
3151 <pre>int lua_iscfunction (lua_State *L, int index);</pre> |
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|
3152 |
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|
3153 <p> |
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3154 Returns 1 if the value at the given index is a C function, |
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|
3155 and 0 otherwise. |
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diff
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|
3156 |
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diff
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|
3157 |
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|
3158 |
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diff
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|
3159 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
3160 |
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|
3161 <hr><h3><a name="lua_isfunction"><code>lua_isfunction</code></a></h3><p> |
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|
3162 <span class="apii">[-0, +0, –]</span> |
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|
3163 <pre>int lua_isfunction (lua_State *L, int index);</pre> |
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|
3164 |
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|
3165 <p> |
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|
3166 Returns 1 if the value at the given index is a function |
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|
3167 (either C or Lua), and 0 otherwise. |
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|
3168 |
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diff
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|
3169 |
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diff
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|
3170 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3171 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
3172 |
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|
3173 <hr><h3><a name="lua_isinteger"><code>lua_isinteger</code></a></h3><p> |
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|
3174 <span class="apii">[-0, +0, –]</span> |
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|
3175 <pre>int lua_isinteger (lua_State *L, int index);</pre> |
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|
3176 |
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|
3177 <p> |
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|
3178 Returns 1 if the value at the given index is an integer |
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|
3179 (that is, the value is a number and is represented as an integer), |
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|
3180 and 0 otherwise. |
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parents:
diff
changeset
|
3181 |
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diff
changeset
|
3182 |
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diff
changeset
|
3183 |
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diff
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|
3184 |
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diff
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|
3185 |
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|
3186 <hr><h3><a name="lua_islightuserdata"><code>lua_islightuserdata</code></a></h3><p> |
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3187 <span class="apii">[-0, +0, –]</span> |
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|
3188 <pre>int lua_islightuserdata (lua_State *L, int index);</pre> |
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|
3189 |
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|
3190 <p> |
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|
3191 Returns 1 if the value at the given index is a light userdata, |
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|
3192 and 0 otherwise. |
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diff
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|
3193 |
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|
3194 |
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|
3195 |
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|
3196 |
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|
3197 |
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|
3198 <hr><h3><a name="lua_isnil"><code>lua_isnil</code></a></h3><p> |
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3199 <span class="apii">[-0, +0, –]</span> |
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|
3200 <pre>int lua_isnil (lua_State *L, int index);</pre> |
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|
3201 |
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|
3202 <p> |
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|
3203 Returns 1 if the value at the given index is <b>nil</b>, |
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|
3204 and 0 otherwise. |
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diff
changeset
|
3205 |
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changeset
|
3206 |
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changeset
|
3207 |
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changeset
|
3208 |
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changeset
|
3209 |
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|
3210 <hr><h3><a name="lua_isnone"><code>lua_isnone</code></a></h3><p> |
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3211 <span class="apii">[-0, +0, –]</span> |
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|
3212 <pre>int lua_isnone (lua_State *L, int index);</pre> |
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3213 |
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|
3214 <p> |
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|
3215 Returns 1 if the given index is not valid, |
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changeset
|
3216 and 0 otherwise. |
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changeset
|
3217 |
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changeset
|
3218 |
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diff
changeset
|
3219 |
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diff
changeset
|
3220 |
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parents:
diff
changeset
|
3221 |
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|
3222 <hr><h3><a name="lua_isnoneornil"><code>lua_isnoneornil</code></a></h3><p> |
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|
3223 <span class="apii">[-0, +0, –]</span> |
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diff
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|
3224 <pre>int lua_isnoneornil (lua_State *L, int index);</pre> |
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|
3225 |
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diff
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|
3226 <p> |
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diff
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|
3227 Returns 1 if the given index is not valid |
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diff
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|
3228 or if the value at this index is <b>nil</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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|
3229 and 0 otherwise. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3230 |
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
3231 |
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parents:
diff
changeset
|
3232 |
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diff
changeset
|
3233 |
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diff
changeset
|
3234 |
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|
3235 <hr><h3><a name="lua_isnumber"><code>lua_isnumber</code></a></h3><p> |
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|
3236 <span class="apii">[-0, +0, –]</span> |
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|
3237 <pre>int lua_isnumber (lua_State *L, int index);</pre> |
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|
3238 |
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diff
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|
3239 <p> |
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|
3240 Returns 1 if the value at the given index is a number |
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diff
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|
3241 or a string convertible to a number, |
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|
3242 and 0 otherwise. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3243 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3244 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3245 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3246 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3247 |
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|
3248 <hr><h3><a name="lua_isstring"><code>lua_isstring</code></a></h3><p> |
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|
3249 <span class="apii">[-0, +0, –]</span> |
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parents:
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|
3250 <pre>int lua_isstring (lua_State *L, int index);</pre> |
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|
3251 |
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diff
changeset
|
3252 <p> |
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|
3253 Returns 1 if the value at the given index is a string |
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parents:
diff
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|
3254 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
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|
3255 and 0 otherwise. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3256 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3257 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3258 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3259 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3260 |
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diff
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|
3261 <hr><h3><a name="lua_istable"><code>lua_istable</code></a></h3><p> |
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|
3262 <span class="apii">[-0, +0, –]</span> |
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parents:
diff
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|
3263 <pre>int lua_istable (lua_State *L, int index);</pre> |
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diff
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|
3264 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3265 <p> |
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diff
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|
3266 Returns 1 if the value at the given index is a table, |
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diff
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|
3267 and 0 otherwise. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3268 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3269 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3270 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3271 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3272 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
3273 <hr><h3><a name="lua_isthread"><code>lua_isthread</code></a></h3><p> |
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|
3274 <span class="apii">[-0, +0, –]</span> |
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diff
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|
3275 <pre>int lua_isthread (lua_State *L, int index);</pre> |
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|
3276 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3277 <p> |
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parents:
diff
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|
3278 Returns 1 if the value at the given index is a thread, |
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diff
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|
3279 and 0 otherwise. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3280 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3281 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3282 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3283 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3284 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
3285 <hr><h3><a name="lua_isuserdata"><code>lua_isuserdata</code></a></h3><p> |
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|
3286 <span class="apii">[-0, +0, –]</span> |
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|
3287 <pre>int lua_isuserdata (lua_State *L, int index);</pre> |
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|
3288 |
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diff
changeset
|
3289 <p> |
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parents:
diff
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|
3290 Returns 1 if the value at the given index is a userdata |
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parents:
diff
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|
3291 (either full or light), and 0 otherwise. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3292 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3293 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3294 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3295 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3296 |
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diff
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|
3297 <hr><h3><a name="lua_isyieldable"><code>lua_isyieldable</code></a></h3><p> |
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|
3298 <span class="apii">[-0, +0, –]</span> |
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parents:
diff
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|
3299 <pre>int lua_isyieldable (lua_State *L);</pre> |
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diff
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|
3300 |
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diff
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|
3301 <p> |
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diff
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|
3302 Returns 1 if the given coroutine can yield, |
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diff
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|
3303 and 0 otherwise. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3304 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3305 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3306 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3307 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3308 |
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diff
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|
3309 <hr><h3><a name="lua_KContext"><code>lua_KContext</code></a></h3> |
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|
3310 <pre>typedef ... lua_KContext;</pre> |
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|
3311 |
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diff
changeset
|
3312 <p> |
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|
3313 The type for continuation-function contexts. |
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|
3314 It must be a numerical type. |
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|
3315 This type is defined as <code>intptr_t</code> |
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|
3316 when <code>intptr_t</code> is available, |
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|
3317 so that it can store pointers too. |
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diff
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|
3318 Otherwise, it is defined as <code>ptrdiff_t</code>. |
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|
3319 |
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diff
changeset
|
3320 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3321 |
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diff
changeset
|
3322 |
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diff
changeset
|
3323 |
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|
3324 <hr><h3><a name="lua_KFunction"><code>lua_KFunction</code></a></h3> |
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|
3325 <pre>typedef int (*lua_KFunction) (lua_State *L, int status, lua_KContext ctx);</pre> |
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|
3326 |
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changeset
|
3327 <p> |
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|
3328 Type for continuation functions (see <a href="#4.7">§4.7</a>). |
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|
3329 |
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diff
changeset
|
3330 |
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diff
changeset
|
3331 |
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changeset
|
3332 |
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changeset
|
3333 |
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|
3334 <hr><h3><a name="lua_len"><code>lua_len</code></a></h3><p> |
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|
3335 <span class="apii">[-0, +1, <em>e</em>]</span> |
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|
3336 <pre>void lua_len (lua_State *L, int index);</pre> |
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|
3337 |
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changeset
|
3338 <p> |
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|
3339 Returns the length of the value at the given index. |
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|
3340 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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|
3341 may trigger a metamethod for the "length" event (see <a href="#2.4">§2.4</a>). |
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3342 The result is pushed on the stack. |
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3343 |
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3344 |
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|
3345 |
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3346 |
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3347 |
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3348 <hr><h3><a name="lua_load"><code>lua_load</code></a></h3><p> |
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3349 <span class="apii">[-0, +1, –]</span> |
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3350 <pre>int lua_load (lua_State *L, |
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3351 lua_Reader reader, |
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3352 void *data, |
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3353 const char *chunkname, |
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3354 const char *mode);</pre> |
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3355 |
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3356 <p> |
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3357 Loads a Lua chunk without running it. |
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3358 If there are no errors, |
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3359 <code>lua_load</code> pushes the compiled chunk as a Lua |
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3360 function on top of the stack. |
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3361 Otherwise, it pushes an error message. |
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3362 |
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3363 |
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3364 <p> |
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3365 The return values of <code>lua_load</code> are: |
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3366 |
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3367 <ul> |
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3368 |
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3369 <li><b><a href="#pdf-LUA_OK"><code>LUA_OK</code></a>: </b> no errors;</li> |
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3370 |
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3371 <li><b><a name="pdf-LUA_ERRSYNTAX"><code>LUA_ERRSYNTAX</code></a>: </b> |
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3372 syntax error during precompilation;</li> |
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3373 |
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3374 <li><b><a href="#pdf-LUA_ERRMEM"><code>LUA_ERRMEM</code></a>: </b> |
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3375 memory allocation error;</li> |
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3376 |
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3377 <li><b><a href="#pdf-LUA_ERRGCMM"><code>LUA_ERRGCMM</code></a>: </b> |
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3378 error while running a <code>__gc</code> metamethod. |
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3379 (This error has no relation with the chunk being loaded. |
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3380 It is generated by the garbage collector.) |
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3381 </li> |
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3382 |
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3383 </ul> |
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3384 |
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3385 <p> |
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3386 The <code>lua_load</code> function uses a user-supplied <code>reader</code> function |
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3387 to read the chunk (see <a href="#lua_Reader"><code>lua_Reader</code></a>). |
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3388 The <code>data</code> argument is an opaque value passed to the reader function. |
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3389 |
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|
3390 |
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3391 <p> |
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3392 The <code>chunkname</code> argument gives a name to the chunk, |
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3393 which is used for error messages and in debug information (see <a href="#4.9">§4.9</a>). |
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3394 |
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|
3395 |
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|
3396 <p> |
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3397 <code>lua_load</code> automatically detects whether the chunk is text or binary |
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3398 and loads it accordingly (see program <code>luac</code>). |
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3399 The string <code>mode</code> works as in function <a href="#pdf-load"><code>load</code></a>, |
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3400 with the addition that |
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3401 a <code>NULL</code> value is equivalent to the string "<code>bt</code>". |
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3402 |
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|
3403 |
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|
3404 <p> |
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3405 <code>lua_load</code> uses the stack internally, |
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3406 so the reader function must always leave the stack |
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3407 unmodified when returning. |
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|
3408 |
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|
3409 |
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|
3410 <p> |
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3411 If the resulting function has upvalues, |
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3412 its first upvalue is set to the value of the global environment |
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3413 stored at index <code>LUA_RIDX_GLOBALS</code> in the registry (see <a href="#4.5">§4.5</a>). |
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3414 When loading main chunks, |
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3415 this upvalue will be the <code>_ENV</code> variable (see <a href="#2.2">§2.2</a>). |
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3416 Other upvalues are initialized with <b>nil</b>. |
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3417 |
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|
3418 |
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|
3419 |
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|
3420 |
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|
3421 |
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|
3422 <hr><h3><a name="lua_newstate"><code>lua_newstate</code></a></h3><p> |
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3423 <span class="apii">[-0, +0, –]</span> |
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|
3424 <pre>lua_State *lua_newstate (lua_Alloc f, void *ud);</pre> |
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3425 |
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|
3426 <p> |
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3427 Creates a new thread running in a new, independent state. |
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3428 Returns <code>NULL</code> if it cannot create the thread or the state |
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3429 (due to lack of memory). |
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3430 The argument <code>f</code> is the allocator function; |
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|
3431 Lua does all memory allocation for this state through this function. |
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3432 The second argument, <code>ud</code>, is an opaque pointer that Lua |
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3433 passes to the allocator in every call. |
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|
3434 |
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|
3435 |
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|
3436 |
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|
3437 |
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3438 |
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|
3439 <hr><h3><a name="lua_newtable"><code>lua_newtable</code></a></h3><p> |
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3440 <span class="apii">[-0, +1, <em>e</em>]</span> |
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3441 <pre>void lua_newtable (lua_State *L);</pre> |
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3442 |
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3443 <p> |
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|
3444 Creates a new empty table and pushes it onto the stack. |
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|
3445 It is equivalent to <code>lua_createtable(L, 0, 0)</code>. |
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3446 |
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|
3447 |
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|
3448 |
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|
3449 |
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3450 |
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3451 <hr><h3><a name="lua_newthread"><code>lua_newthread</code></a></h3><p> |
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3452 <span class="apii">[-0, +1, <em>e</em>]</span> |
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|
3453 <pre>lua_State *lua_newthread (lua_State *L);</pre> |
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3454 |
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|
3455 <p> |
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|
3456 Creates a new thread, pushes it on the stack, |
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3457 and returns a pointer to a <a href="#lua_State"><code>lua_State</code></a> that represents this new thread. |
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3458 The new thread returned by this function shares with the original thread |
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3459 its global environment, |
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3460 but has an independent execution stack. |
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3461 |
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|
3462 |
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|
3463 <p> |
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3464 There is no explicit function to close or to destroy a thread. |
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3465 Threads are subject to garbage collection, |
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3466 like any Lua object. |
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|
3467 |
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|
3468 |
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diff
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|
3469 |
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|
3470 |
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|
3471 |
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3472 <hr><h3><a name="lua_newuserdata"><code>lua_newuserdata</code></a></h3><p> |
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3473 <span class="apii">[-0, +1, <em>e</em>]</span> |
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|
3474 <pre>void *lua_newuserdata (lua_State *L, size_t size);</pre> |
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3475 |
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3476 <p> |
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|
3477 This function allocates a new block of memory with the given size, |
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3478 pushes onto the stack a new full userdata with the block address, |
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3479 and returns this address. |
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3480 The host program can freely use this memory. |
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3481 |
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|
3482 |
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3483 |
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3484 |
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|
3485 |
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3486 <hr><h3><a name="lua_next"><code>lua_next</code></a></h3><p> |
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3487 <span class="apii">[-1, +(2|0), <em>e</em>]</span> |
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3488 <pre>int lua_next (lua_State *L, int index);</pre> |
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3489 |
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|
3490 <p> |
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3491 Pops a key from the stack, |
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3492 and pushes a key–value pair from the table at the given index |
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3493 (the "next" pair after the given key). |
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3494 If there are no more elements in the table, |
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|
3495 then <a href="#lua_next"><code>lua_next</code></a> returns 0 (and pushes nothing). |
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|
3496 |
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|
3497 |
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|
3498 <p> |
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3499 A typical traversal looks like this: |
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|
3500 |
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|
3501 <pre> |
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3502 /* table is in the stack at index 't' */ |
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3503 lua_pushnil(L); /* first key */ |
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3504 while (lua_next(L, t) != 0) { |
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3505 /* uses 'key' (at index -2) and 'value' (at index -1) */ |
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3506 printf("%s - %s\n", |
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3507 lua_typename(L, lua_type(L, -2)), |
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3508 lua_typename(L, lua_type(L, -1))); |
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3509 /* removes 'value'; keeps 'key' for next iteration */ |
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3510 lua_pop(L, 1); |
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3511 } |
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3512 </pre> |
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|
3513 |
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|
3514 <p> |
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|
3515 While traversing a table, |
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3516 do not call <a href="#lua_tolstring"><code>lua_tolstring</code></a> directly on a key, |
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|
3517 unless you know that the key is actually a string. |
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3518 Recall that <a href="#lua_tolstring"><code>lua_tolstring</code></a> may change |
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3519 the value at the given index; |
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|
3520 this confuses the next call to <a href="#lua_next"><code>lua_next</code></a>. |
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|
3521 |
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|
3522 |
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|
3523 <p> |
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|
3524 See function <a href="#pdf-next"><code>next</code></a> for the caveats of modifying |
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|
3525 the table during its traversal. |
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|
3526 |
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|
3527 |
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|
3528 |
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|
3529 |
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|
3530 |
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|
3531 <hr><h3><a name="lua_Number"><code>lua_Number</code></a></h3> |
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|
3532 <pre>typedef double lua_Number;</pre> |
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|
3533 |
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|
3534 <p> |
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|
3535 The type of floats in Lua. |
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|
3536 |
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|
3537 |
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|
3538 <p> |
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|
3539 By default this type is double, |
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|
3540 but that can be changed to a single float. |
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|
3541 (See <code>LUA_REAL</code> in <code>luaconf.h</code>.) |
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|
3542 |
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|
3543 |
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|
3544 |
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|
3545 |
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|
3546 |
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|
3547 <hr><h3><a name="lua_numbertointeger"><code>lua_numbertointeger</code></a></h3> |
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|
3548 <pre>int lua_numbertointeger (lua_Number n, lua_Integer *p);</pre> |
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|
3549 |
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|
3550 <p> |
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|
3551 Converts a Lua float to a Lua integer. |
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|
3552 This macro assumes that <code>n</code> has an integral value. |
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|
3553 If that value is within the range of Lua integers, |
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|
3554 it is converted to an integer and assigned to <code>*p</code>. |
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|
3555 The macro results in a boolean indicating whether the |
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|
3556 conversion was successful. |
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|
3557 (Note that this range test can be tricky to do |
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|
3558 correctly without this macro, |
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|
3559 due to roundings.) |
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|
3560 |
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|
3561 |
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|
3562 <p> |
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|
3563 This macro may evaluate its arguments more than once. |
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|
3564 |
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|
3565 |
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|
3566 |
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|
3567 |
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|
3568 |
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|
3569 <hr><h3><a name="lua_pcall"><code>lua_pcall</code></a></h3><p> |
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|
3570 <span class="apii">[-(nargs + 1), +(nresults|1), –]</span> |
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|
3571 <pre>int lua_pcall (lua_State *L, int nargs, int nresults, int msgh);</pre> |
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|
3572 |
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|
3573 <p> |
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|
3574 Calls a function in protected mode. |
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|
3575 |
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|
3576 |
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|
3577 <p> |
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|
3578 Both <code>nargs</code> and <code>nresults</code> have the same meaning as |
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3579 in <a href="#lua_call"><code>lua_call</code></a>. |
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|
3580 If there are no errors during the call, |
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|
3581 <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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|
3582 However, if there is any error, |
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|
3583 <a href="#lua_pcall"><code>lua_pcall</code></a> catches it, |
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|
3584 pushes a single value on the stack (the error message), |
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|
3585 and returns an error code. |
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3586 Like <a href="#lua_call"><code>lua_call</code></a>, |
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3587 <a href="#lua_pcall"><code>lua_pcall</code></a> always removes the function |
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3588 and its arguments from the stack. |
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|
3589 |
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|
3590 |
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3591 <p> |
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3592 If <code>msgh</code> is 0, |
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3593 then the error message returned on the stack |
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3594 is exactly the original error message. |
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3595 Otherwise, <code>msgh</code> is the stack index of a |
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3596 <em>message handler</em>. |
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3597 (In the current implementation, this index cannot be a pseudo-index.) |
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3598 In case of runtime errors, |
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3599 this function will be called with the error message |
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3600 and its return value will be the message |
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3601 returned on the stack by <a href="#lua_pcall"><code>lua_pcall</code></a>. |
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3602 |
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3603 |
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3604 <p> |
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3605 Typically, the message handler is used to add more debug |
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3606 information to the error message, such as a stack traceback. |
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3607 Such information cannot be gathered after the return of <a href="#lua_pcall"><code>lua_pcall</code></a>, |
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3608 since by then the stack has unwound. |
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3609 |
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3610 |
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3611 <p> |
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3612 The <a href="#lua_pcall"><code>lua_pcall</code></a> function returns one of the following constants |
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3613 (defined in <code>lua.h</code>): |
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3614 |
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3615 <ul> |
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3616 |
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3617 <li><b><a name="pdf-LUA_OK"><code>LUA_OK</code></a> (0): </b> |
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3618 success.</li> |
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|
3619 |
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3620 <li><b><a name="pdf-LUA_ERRRUN"><code>LUA_ERRRUN</code></a>: </b> |
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3621 a runtime error. |
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|
3622 </li> |
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|
3623 |
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3624 <li><b><a name="pdf-LUA_ERRMEM"><code>LUA_ERRMEM</code></a>: </b> |
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3625 memory allocation error. |
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3626 For such errors, Lua does not call the message handler. |
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3627 </li> |
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|
3628 |
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3629 <li><b><a name="pdf-LUA_ERRERR"><code>LUA_ERRERR</code></a>: </b> |
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3630 error while running the message handler. |
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3631 </li> |
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|
3632 |
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3633 <li><b><a name="pdf-LUA_ERRGCMM"><code>LUA_ERRGCMM</code></a>: </b> |
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3634 error while running a <code>__gc</code> metamethod. |
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3635 (This error typically has no relation with the function being called.) |
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3636 </li> |
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|
3637 |
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|
3638 </ul> |
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|
3639 |
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|
3640 |
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|
3641 |
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3642 |
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3643 <hr><h3><a name="lua_pcallk"><code>lua_pcallk</code></a></h3><p> |
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3644 <span class="apii">[-(nargs + 1), +(nresults|1), –]</span> |
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3645 <pre>int lua_pcallk (lua_State *L, |
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3646 int nargs, |
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3647 int nresults, |
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3648 int msgh, |
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3649 lua_KContext ctx, |
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|
3650 lua_KFunction k);</pre> |
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|
3651 |
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|
3652 <p> |
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3653 This function behaves exactly like <a href="#lua_pcall"><code>lua_pcall</code></a>, |
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|
3654 but allows the called function to yield (see <a href="#4.7">§4.7</a>). |
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|
3655 |
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|
3656 |
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|
3657 |
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|
3658 |
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|
3659 |
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|
3660 <hr><h3><a name="lua_pop"><code>lua_pop</code></a></h3><p> |
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3661 <span class="apii">[-n, +0, –]</span> |
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|
3662 <pre>void lua_pop (lua_State *L, int n);</pre> |
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|
3663 |
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|
3664 <p> |
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|
3665 Pops <code>n</code> elements from the stack. |
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|
3666 |
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|
3667 |
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|
3668 |
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|
3669 |
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|
3670 |
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|
3671 <hr><h3><a name="lua_pushboolean"><code>lua_pushboolean</code></a></h3><p> |
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3672 <span class="apii">[-0, +1, –]</span> |
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|
3673 <pre>void lua_pushboolean (lua_State *L, int b);</pre> |
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|
3674 |
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|
3675 <p> |
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3676 Pushes a boolean value with value <code>b</code> onto the stack. |
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|
3677 |
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|
3678 |
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|
3679 |
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|
3680 |
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|
3681 |
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|
3682 <hr><h3><a name="lua_pushcclosure"><code>lua_pushcclosure</code></a></h3><p> |
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3683 <span class="apii">[-n, +1, <em>e</em>]</span> |
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|
3684 <pre>void lua_pushcclosure (lua_State *L, lua_CFunction fn, int n);</pre> |
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|
3685 |
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|
3686 <p> |
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|
3687 Pushes a new C closure onto the stack. |
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|
3688 |
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|
3689 |
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|
3690 <p> |
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|
3691 When a C function is created, |
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3692 it is possible to associate some values with it, |
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|
3693 thus creating a C closure (see <a href="#4.4">§4.4</a>); |
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3694 these values are then accessible to the function whenever it is called. |
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|
3695 To associate values with a C function, |
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3696 first these values must be pushed onto the stack |
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3697 (when there are multiple values, the first value is pushed first). |
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3698 Then <a href="#lua_pushcclosure"><code>lua_pushcclosure</code></a> |
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3699 is called to create and push the C function onto the stack, |
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3700 with the argument <code>n</code> telling how many values will be |
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3701 associated with the function. |
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|
3702 <a href="#lua_pushcclosure"><code>lua_pushcclosure</code></a> also pops these values from the stack. |
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3703 |
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|
3704 |
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|
3705 <p> |
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|
3706 The maximum value for <code>n</code> is 255. |
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|
3707 |
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3708 |
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3709 <p> |
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|
3710 When <code>n</code> is zero, |
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|
3711 this function creates a <em>light C function</em>, |
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|
3712 which is just a pointer to the C function. |
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|
3713 In that case, it never raises a memory error. |
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|
3714 |
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3715 |
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|
3716 |
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diff
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|
3717 |
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|
3718 |
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|
3719 <hr><h3><a name="lua_pushcfunction"><code>lua_pushcfunction</code></a></h3><p> |
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3720 <span class="apii">[-0, +1, –]</span> |
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|
3721 <pre>void lua_pushcfunction (lua_State *L, lua_CFunction f);</pre> |
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3722 |
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|
3723 <p> |
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|
3724 Pushes a C function onto the stack. |
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|
3725 This function receives a pointer to a C function |
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3726 and pushes onto the stack a Lua value of type <code>function</code> that, |
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3727 when called, invokes the corresponding C function. |
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|
3728 |
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|
3729 |
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|
3730 <p> |
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|
3731 Any function to be registered in Lua must |
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|
3732 follow the correct protocol to receive its parameters |
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|
3733 and return its results (see <a href="#lua_CFunction"><code>lua_CFunction</code></a>). |
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|
3734 |
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diff
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|
3735 |
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|
3736 <p> |
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|
3737 <code>lua_pushcfunction</code> is defined as a macro: |
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|
3738 |
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|
3739 <pre> |
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|
3740 #define lua_pushcfunction(L,f) lua_pushcclosure(L,f,0) |
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|
3741 </pre><p> |
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|
3742 Note that <code>f</code> is used twice. |
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|
3743 |
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diff
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|
3744 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
3745 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
3746 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
3747 |
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|
3748 <hr><h3><a name="lua_pushfstring"><code>lua_pushfstring</code></a></h3><p> |
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|
3749 <span class="apii">[-0, +1, <em>e</em>]</span> |
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|
3750 <pre>const char *lua_pushfstring (lua_State *L, const char *fmt, ...);</pre> |
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|
3751 |
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|
3752 <p> |
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|
3753 Pushes onto the stack a formatted string |
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|
3754 and returns a pointer to this string. |
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|
3755 It is similar to the ISO C function <code>sprintf</code>, |
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|
3756 but has some important differences: |
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diff
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|
3757 |
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diff
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|
3758 <ul> |
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diff
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|
3759 |
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diff
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|
3760 <li> |
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|
3761 You do not have to allocate space for the result: |
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|
3762 the result is a Lua string and Lua takes care of memory allocation |
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|
3763 (and deallocation, through garbage collection). |
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|
3764 </li> |
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diff
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|
3765 |
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diff
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|
3766 <li> |
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|
3767 The conversion specifiers are quite restricted. |
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|
3768 There are no flags, widths, or precisions. |
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|
3769 The conversion specifiers can only be |
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|
3770 '<code>%%</code>' (inserts the character '<code>%</code>'), |
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|
3771 '<code>%s</code>' (inserts a zero-terminated string, with no size restrictions), |
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|
3772 '<code>%f</code>' (inserts a <a href="#lua_Number"><code>lua_Number</code></a>), |
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|
3773 '<code>%L</code>' (inserts a <a href="#lua_Integer"><code>lua_Integer</code></a>), |
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|
3774 '<code>%p</code>' (inserts a pointer as a hexadecimal numeral), |
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|
3775 '<code>%d</code>' (inserts an <code>int</code>), |
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|
3776 '<code>%c</code>' (inserts an <code>int</code> as a one-byte character), and |
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|
3777 '<code>%U</code>' (inserts a <code>long int</code> as a UTF-8 byte sequence). |
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|
3778 </li> |
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diff
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|
3779 |
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diff
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|
3780 </ul> |
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diff
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|
3781 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3782 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3783 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3784 |
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diff
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|
3785 <hr><h3><a name="lua_pushglobaltable"><code>lua_pushglobaltable</code></a></h3><p> |
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|
3786 <span class="apii">[-0, +1, –]</span> |
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diff
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|
3787 <pre>void lua_pushglobaltable (lua_State *L);</pre> |
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|
3788 |
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diff
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|
3789 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
3790 Pushes the global environment onto the stack. |
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diff
changeset
|
3791 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3792 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3793 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3794 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3795 |
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|
3796 <hr><h3><a name="lua_pushinteger"><code>lua_pushinteger</code></a></h3><p> |
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|
3797 <span class="apii">[-0, +1, –]</span> |
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|
3798 <pre>void lua_pushinteger (lua_State *L, lua_Integer n);</pre> |
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|
3799 |
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diff
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|
3800 <p> |
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diff
changeset
|
3801 Pushes an integer with value <code>n</code> onto the stack. |
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|
3802 |
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|
3803 |
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|
3804 |
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|
3805 |
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|
3806 |
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|
3807 <hr><h3><a name="lua_pushlightuserdata"><code>lua_pushlightuserdata</code></a></h3><p> |
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|
3808 <span class="apii">[-0, +1, –]</span> |
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|
3809 <pre>void lua_pushlightuserdata (lua_State *L, void *p);</pre> |
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|
3810 |
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changeset
|
3811 <p> |
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|
3812 Pushes a light userdata onto the stack. |
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|
3813 |
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diff
changeset
|
3814 |
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changeset
|
3815 <p> |
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|
3816 Userdata represent C values in Lua. |
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|
3817 A <em>light userdata</em> represents a pointer, a <code>void*</code>. |
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|
3818 It is a value (like a number): |
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3819 you do not create it, it has no individual metatable, |
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3820 and it is not collected (as it was never created). |
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|
3821 A light userdata is equal to "any" |
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|
3822 light userdata with the same C address. |
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|
3823 |
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|
3824 |
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|
3825 |
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|
3826 |
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changeset
|
3827 |
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|
3828 <hr><h3><a name="lua_pushliteral"><code>lua_pushliteral</code></a></h3><p> |
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|
3829 <span class="apii">[-0, +1, <em>e</em>]</span> |
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|
3830 <pre>const char *lua_pushliteral (lua_State *L, const char *s);</pre> |
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3831 |
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|
3832 <p> |
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|
3833 This macro is equivalent to <a href="#lua_pushlstring"><code>lua_pushlstring</code></a>, |
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3834 but can be used only when <code>s</code> is a literal string. |
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|
3835 It automatically provides the string length. |
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|
3836 |
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3837 |
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3838 |
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3839 |
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3840 |
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3841 <hr><h3><a name="lua_pushlstring"><code>lua_pushlstring</code></a></h3><p> |
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3842 <span class="apii">[-0, +1, <em>e</em>]</span> |
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|
3843 <pre>const char *lua_pushlstring (lua_State *L, const char *s, size_t len);</pre> |
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3844 |
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|
3845 <p> |
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|
3846 Pushes the string pointed to by <code>s</code> with size <code>len</code> |
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3847 onto the stack. |
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3848 Lua makes (or reuses) an internal copy of the given string, |
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3849 so the memory at <code>s</code> can be freed or reused immediately after |
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3850 the function returns. |
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3851 The string can contain any binary data, |
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|
3852 including embedded zeros. |
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3853 |
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3854 |
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3855 <p> |
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3856 Returns a pointer to the internal copy of the string. |
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|
3857 |
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3858 |
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diff
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3859 |
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|
3860 |
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diff
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3861 |
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3862 <hr><h3><a name="lua_pushnil"><code>lua_pushnil</code></a></h3><p> |
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3863 <span class="apii">[-0, +1, –]</span> |
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|
3864 <pre>void lua_pushnil (lua_State *L);</pre> |
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|
3865 |
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|
3866 <p> |
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|
3867 Pushes a nil value onto the stack. |
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|
3868 |
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diff
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|
3869 |
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diff
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|
3870 |
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|
3871 |
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diff
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|
3872 |
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|
3873 <hr><h3><a name="lua_pushnumber"><code>lua_pushnumber</code></a></h3><p> |
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|
3874 <span class="apii">[-0, +1, –]</span> |
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|
3875 <pre>void lua_pushnumber (lua_State *L, lua_Number n);</pre> |
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|
3876 |
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|
3877 <p> |
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|
3878 Pushes a float with value <code>n</code> onto the stack. |
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|
3879 |
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diff
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|
3880 |
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diff
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|
3881 |
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diff
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|
3882 |
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diff
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|
3883 |
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|
3884 <hr><h3><a name="lua_pushstring"><code>lua_pushstring</code></a></h3><p> |
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|
3885 <span class="apii">[-0, +1, <em>e</em>]</span> |
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|
3886 <pre>const char *lua_pushstring (lua_State *L, const char *s);</pre> |
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|
3887 |
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|
3888 <p> |
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|
3889 Pushes the zero-terminated string pointed to by <code>s</code> |
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|
3890 onto the stack. |
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|
3891 Lua makes (or reuses) an internal copy of the given string, |
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diff
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|
3892 so the memory at <code>s</code> can be freed or reused immediately after |
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|
3893 the function returns. |
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diff
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|
3894 |
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diff
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|
3895 |
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|
3896 <p> |
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|
3897 Returns a pointer to the internal copy of the string. |
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|
3898 |
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diff
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|
3899 |
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|
3900 <p> |
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|
3901 If <code>s</code> is <code>NULL</code>, pushes <b>nil</b> and returns <code>NULL</code>. |
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|
3902 |
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|
3903 |
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|
3904 |
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|
3905 |
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|
3906 |
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|
3907 <hr><h3><a name="lua_pushthread"><code>lua_pushthread</code></a></h3><p> |
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3908 <span class="apii">[-0, +1, –]</span> |
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|
3909 <pre>int lua_pushthread (lua_State *L);</pre> |
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|
3910 |
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|
3911 <p> |
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|
3912 Pushes the thread represented by <code>L</code> onto the stack. |
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|
3913 Returns 1 if this thread is the main thread of its state. |
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|
3914 |
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|
3915 |
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|
3916 |
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|
3917 |
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|
3918 |
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|
3919 <hr><h3><a name="lua_pushvalue"><code>lua_pushvalue</code></a></h3><p> |
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3920 <span class="apii">[-0, +1, –]</span> |
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|
3921 <pre>void lua_pushvalue (lua_State *L, int index);</pre> |
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|
3922 |
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|
3923 <p> |
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|
3924 Pushes a copy of the element at the given index |
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|
3925 onto the stack. |
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|
3926 |
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|
3927 |
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|
3928 |
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|
3929 |
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diff
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|
3930 |
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|
3931 <hr><h3><a name="lua_pushvfstring"><code>lua_pushvfstring</code></a></h3><p> |
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|
3932 <span class="apii">[-0, +1, <em>e</em>]</span> |
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|
3933 <pre>const char *lua_pushvfstring (lua_State *L, |
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|
3934 const char *fmt, |
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|
3935 va_list argp);</pre> |
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|
3936 |
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|
3937 <p> |
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|
3938 Equivalent to <a href="#lua_pushfstring"><code>lua_pushfstring</code></a>, except that it receives a <code>va_list</code> |
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3939 instead of a variable number of arguments. |
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|
3940 |
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|
3941 |
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|
3942 |
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|
3943 |
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3944 |
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|
3945 <hr><h3><a name="lua_rawequal"><code>lua_rawequal</code></a></h3><p> |
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3946 <span class="apii">[-0, +0, –]</span> |
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|
3947 <pre>int lua_rawequal (lua_State *L, int index1, int index2);</pre> |
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3948 |
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|
3949 <p> |
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|
3950 Returns 1 if the two values in indices <code>index1</code> and |
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|
3951 <code>index2</code> are primitively equal |
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|
3952 (that is, without calling metamethods). |
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|
3953 Otherwise returns 0. |
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|
3954 Also returns 0 if any of the indices are not valid. |
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|
3955 |
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diff
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|
3956 |
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diff
changeset
|
3957 |
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diff
changeset
|
3958 |
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diff
changeset
|
3959 |
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|
3960 <hr><h3><a name="lua_rawget"><code>lua_rawget</code></a></h3><p> |
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|
3961 <span class="apii">[-1, +1, –]</span> |
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|
3962 <pre>int lua_rawget (lua_State *L, int index);</pre> |
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|
3963 |
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diff
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|
3964 <p> |
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|
3965 Similar to <a href="#lua_gettable"><code>lua_gettable</code></a>, but does a raw access |
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|
3966 (i.e., without metamethods). |
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diff
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|
3967 |
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parents:
diff
changeset
|
3968 |
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parents:
diff
changeset
|
3969 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3970 |
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diff
changeset
|
3971 |
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|
3972 <hr><h3><a name="lua_rawgeti"><code>lua_rawgeti</code></a></h3><p> |
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|
3973 <span class="apii">[-0, +1, –]</span> |
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|
3974 <pre>int lua_rawgeti (lua_State *L, int index, lua_Integer n);</pre> |
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|
3975 |
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|
3976 <p> |
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|
3977 Pushes onto the stack the value <code>t[n]</code>, |
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parents:
diff
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|
3978 where <code>t</code> is the table at the given index. |
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diff
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|
3979 The access is raw; |
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diff
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|
3980 that is, it does not invoke metamethods. |
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|
3981 |
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diff
changeset
|
3982 |
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|
3983 <p> |
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|
3984 Returns the type of the pushed value. |
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diff
changeset
|
3985 |
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diff
changeset
|
3986 |
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parents:
diff
changeset
|
3987 |
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parents:
diff
changeset
|
3988 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3989 |
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diff
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|
3990 <hr><h3><a name="lua_rawgetp"><code>lua_rawgetp</code></a></h3><p> |
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|
3991 <span class="apii">[-0, +1, –]</span> |
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diff
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|
3992 <pre>int lua_rawgetp (lua_State *L, int index, const void *p);</pre> |
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|
3993 |
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diff
changeset
|
3994 <p> |
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parents:
diff
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|
3995 Pushes onto the stack the value <code>t[k]</code>, |
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parents:
diff
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|
3996 where <code>t</code> is the table at the given index and |
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parents:
diff
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|
3997 <code>k</code> is the pointer <code>p</code> represented as a light userdata. |
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parents:
diff
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|
3998 The access is raw; |
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parents:
diff
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|
3999 that is, it does not invoke metamethods. |
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diff
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|
4000 |
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diff
changeset
|
4001 |
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diff
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|
4002 <p> |
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diff
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|
4003 Returns the type of the pushed value. |
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|
4004 |
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|
4005 |
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|
4006 |
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changeset
|
4007 |
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diff
changeset
|
4008 |
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|
4009 <hr><h3><a name="lua_rawlen"><code>lua_rawlen</code></a></h3><p> |
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|
4010 <span class="apii">[-0, +0, –]</span> |
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|
4011 <pre>size_t lua_rawlen (lua_State *L, int index);</pre> |
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|
4012 |
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|
4013 <p> |
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diff
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|
4014 Returns the raw "length" of the value at the given index: |
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parents:
diff
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|
4015 for strings, this is the string length; |
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parents:
diff
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|
4016 for tables, this is the result of the length operator ('<code>#</code>') |
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|
4017 with no metamethods; |
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parents:
diff
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|
4018 for userdata, this is the size of the block of memory allocated |
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|
4019 for the userdata; |
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|
4020 for other values, it is 0. |
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parents:
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changeset
|
4021 |
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diff
changeset
|
4022 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
4023 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
4024 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
4025 |
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diff
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|
4026 <hr><h3><a name="lua_rawset"><code>lua_rawset</code></a></h3><p> |
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|
4027 <span class="apii">[-2, +0, <em>e</em>]</span> |
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|
4028 <pre>void lua_rawset (lua_State *L, int index);</pre> |
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|
4029 |
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diff
changeset
|
4030 <p> |
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diff
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|
4031 Similar to <a href="#lua_settable"><code>lua_settable</code></a>, but does a raw assignment |
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parents:
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|
4032 (i.e., without metamethods). |
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parents:
diff
changeset
|
4033 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
4034 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
4035 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
4036 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
4037 |
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|
4038 <hr><h3><a name="lua_rawseti"><code>lua_rawseti</code></a></h3><p> |
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|
4039 <span class="apii">[-1, +0, <em>e</em>]</span> |
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diff
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|
4040 <pre>void lua_rawseti (lua_State *L, int index, lua_Integer i);</pre> |
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|
4041 |
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|
4042 <p> |
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|
4043 Does the equivalent of <code>t[i] = v</code>, |
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diff
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|
4044 where <code>t</code> is the table at the given index |
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diff
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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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diff
changeset
|
4047 |
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|
4048 <p> |
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|
4049 This function pops the value from the stack. |
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|
4050 The assignment is raw; |
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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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diff
changeset
|
4055 |
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changeset
|
4056 |
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|
4057 <hr><h3><a name="lua_rawsetp"><code>lua_rawsetp</code></a></h3><p> |
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|
4058 <span class="apii">[-1, +0, <em>e</em>]</span> |
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|
4059 <pre>void lua_rawsetp (lua_State *L, int index, const void *p);</pre> |
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|
4060 |
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|
4061 <p> |
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|
4062 Does the equivalent of <code>t[k] = v</code>, |
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changeset
|
4063 where <code>t</code> is the table at the given index, |
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changeset
|
4064 <code>k</code> is the pointer <code>p</code> represented as a light userdata, |
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|
4065 and <code>v</code> is the value at the top of the stack. |
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|
4066 |
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diff
changeset
|
4067 |
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|
4068 <p> |
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|
4069 This function pops the value from the stack. |
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diff
changeset
|
4070 The assignment is raw; |
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diff
changeset
|
4071 that is, it does not invoke metamethods. |
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changeset
|
4072 |
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changeset
|
4073 |
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4074 |
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4075 |
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4076 |
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4077 <hr><h3><a name="lua_Reader"><code>lua_Reader</code></a></h3> |
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4078 <pre>typedef const char * (*lua_Reader) (lua_State *L, |
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4079 void *data, |
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4080 size_t *size);</pre> |
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4081 |
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4082 <p> |
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4083 The reader function used by <a href="#lua_load"><code>lua_load</code></a>. |
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4084 Every time it needs another piece of the chunk, |
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4085 <a href="#lua_load"><code>lua_load</code></a> calls the reader, |
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4086 passing along its <code>data</code> parameter. |
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4087 The reader must return a pointer to a block of memory |
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4088 with a new piece of the chunk |
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4089 and set <code>size</code> to the block size. |
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4090 The block must exist until the reader function is called again. |
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4091 To signal the end of the chunk, |
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4092 the reader must return <code>NULL</code> or set <code>size</code> to zero. |
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4093 The reader function may return pieces of any size greater than zero. |
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4094 |
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4095 |
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4096 |
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4097 |
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4098 |
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4099 <hr><h3><a name="lua_register"><code>lua_register</code></a></h3><p> |
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4100 <span class="apii">[-0, +0, <em>e</em>]</span> |
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4101 <pre>void lua_register (lua_State *L, const char *name, lua_CFunction f);</pre> |
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4102 |
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4103 <p> |
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4104 Sets the C function <code>f</code> as the new value of global <code>name</code>. |
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4105 It is defined as a macro: |
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4106 |
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4107 <pre> |
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4108 #define lua_register(L,n,f) \ |
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4109 (lua_pushcfunction(L, f), lua_setglobal(L, n)) |
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4110 </pre> |
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4111 |
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4112 |
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4113 |
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4114 |
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4115 <hr><h3><a name="lua_remove"><code>lua_remove</code></a></h3><p> |
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4116 <span class="apii">[-1, +0, –]</span> |
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4117 <pre>void lua_remove (lua_State *L, int index);</pre> |
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4118 |
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4119 <p> |
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4120 Removes the element at the given valid index, |
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4121 shifting down the elements above this index to fill the gap. |
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4122 This function cannot be called with a pseudo-index, |
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4123 because a pseudo-index is not an actual stack position. |
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4124 |
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4125 |
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4126 |
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4127 |
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4128 |
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4129 <hr><h3><a name="lua_replace"><code>lua_replace</code></a></h3><p> |
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4130 <span class="apii">[-1, +0, –]</span> |
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4131 <pre>void lua_replace (lua_State *L, int index);</pre> |
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4132 |
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4133 <p> |
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4134 Moves the top element into the given valid index |
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4135 without shifting any element |
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4136 (therefore replacing the value at the given index), |
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4137 and then pops the top element. |
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4138 |
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4139 |
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4140 |
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4141 |
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4142 |
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4143 <hr><h3><a name="lua_resume"><code>lua_resume</code></a></h3><p> |
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4144 <span class="apii">[-?, +?, –]</span> |
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4145 <pre>int lua_resume (lua_State *L, lua_State *from, int nargs);</pre> |
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4146 |
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4147 <p> |
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4148 Starts and resumes a coroutine in a given thread. |
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4149 |
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|
4150 |
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|
4151 <p> |
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4152 To start a coroutine, |
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4153 you push onto the thread stack the main function plus any arguments; |
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4154 then you call <a href="#lua_resume"><code>lua_resume</code></a>, |
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4155 with <code>nargs</code> being the number of arguments. |
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4156 This call returns when the coroutine suspends or finishes its execution. |
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4157 When it returns, the stack contains all values passed to <a href="#lua_yield"><code>lua_yield</code></a>, |
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4158 or all values returned by the body function. |
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4159 <a href="#lua_resume"><code>lua_resume</code></a> returns |
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4160 <a href="#pdf-LUA_YIELD"><code>LUA_YIELD</code></a> if the coroutine yields, |
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4161 <a href="#pdf-LUA_OK"><code>LUA_OK</code></a> if the coroutine finishes its execution |
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4162 without errors, |
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4163 or an error code in case of errors (see <a href="#lua_pcall"><code>lua_pcall</code></a>). |
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4164 |
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4165 |
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4166 <p> |
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4167 In case of errors, |
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4168 the stack is not unwound, |
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4169 so you can use the debug API over it. |
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4170 The error message is on the top of the stack. |
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4171 |
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4172 |
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4173 <p> |
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4174 To resume a coroutine, |
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4175 you remove any results from the last <a href="#lua_yield"><code>lua_yield</code></a>, |
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4176 put on its stack only the values to |
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4177 be passed as results from <code>yield</code>, |
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4178 and then call <a href="#lua_resume"><code>lua_resume</code></a>. |
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4179 |
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4180 |
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4181 <p> |
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4182 The parameter <code>from</code> represents the coroutine that is resuming <code>L</code>. |
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4183 If there is no such coroutine, |
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4184 this parameter can be <code>NULL</code>. |
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4185 |
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4186 |
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4187 |
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4188 |
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4189 |
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4190 <hr><h3><a name="lua_rotate"><code>lua_rotate</code></a></h3><p> |
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4191 <span class="apii">[-0, +0, –]</span> |
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4192 <pre>void lua_rotate (lua_State *L, int idx, int n);</pre> |
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4193 |
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4194 <p> |
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4195 Rotates the stack elements from <code>idx</code> to the top <code>n</code> positions |
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|
4196 in the direction of the top, for a positive <code>n</code>, |
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|
4197 or <code>-n</code> positions in the direction of the bottom, |
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diff
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|
4198 for a negative <code>n</code>. |
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|
4199 The absolute value of <code>n</code> must not be greater than the size |
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|
4200 of the slice being rotated. |
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diff
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|
4201 |
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diff
changeset
|
4202 |
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diff
changeset
|
4203 |
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diff
changeset
|
4204 |
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diff
changeset
|
4205 |
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|
4206 <hr><h3><a name="lua_setallocf"><code>lua_setallocf</code></a></h3><p> |
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|
4207 <span class="apii">[-0, +0, –]</span> |
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|
4208 <pre>void lua_setallocf (lua_State *L, lua_Alloc f, void *ud);</pre> |
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|
4209 |
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diff
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|
4210 <p> |
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diff
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|
4211 Changes the allocator function of a given state to <code>f</code> |
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|
4212 with user data <code>ud</code>. |
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|
4213 |
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diff
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|
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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diff
changeset
|
4216 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
4217 |
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|
4218 <hr><h3><a name="lua_setfield"><code>lua_setfield</code></a></h3><p> |
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4219 <span class="apii">[-1, +0, <em>e</em>]</span> |
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|
4220 <pre>void lua_setfield (lua_State *L, int index, const char *k);</pre> |
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|
4221 |
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changeset
|
4222 <p> |
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diff
changeset
|
4223 Does the equivalent to <code>t[k] = v</code>, |
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parents:
diff
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|
4224 where <code>t</code> is the value at the given index |
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|
4225 and <code>v</code> is the value at the top of the stack. |
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|
4226 |
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changeset
|
4227 |
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|
4228 <p> |
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|
4229 This function pops the value from the stack. |
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diff
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|
4230 As in Lua, this function may trigger a metamethod |
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|
4231 for the "newindex" event (see <a href="#2.4">§2.4</a>). |
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|
4232 |
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diff
changeset
|
4233 |
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diff
changeset
|
4234 |
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diff
changeset
|
4235 |
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diff
changeset
|
4236 |
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|
4237 <hr><h3><a name="lua_setglobal"><code>lua_setglobal</code></a></h3><p> |
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|
4238 <span class="apii">[-1, +0, <em>e</em>]</span> |
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|
4239 <pre>void lua_setglobal (lua_State *L, const char *name);</pre> |
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|
4240 |
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diff
changeset
|
4241 <p> |
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diff
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|
4242 Pops a value from the stack and |
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diff
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|
4243 sets it as the new value of global <code>name</code>. |
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|
4244 |
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diff
changeset
|
4245 |
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diff
changeset
|
4246 |
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diff
changeset
|
4247 |
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diff
changeset
|
4248 |
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|
4249 <hr><h3><a name="lua_seti"><code>lua_seti</code></a></h3><p> |
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|
4250 <span class="apii">[-1, +0, <em>e</em>]</span> |
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|
4251 <pre>void lua_seti (lua_State *L, int index, lua_Integer n);</pre> |
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|
4252 |
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|
4253 <p> |
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diff
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|
4254 Does the equivalent to <code>t[n] = v</code>, |
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parents:
diff
changeset
|
4255 where <code>t</code> is the value at the given index |
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diff
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|
4256 and <code>v</code> is the value at the top of the stack. |
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|
4257 |
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diff
changeset
|
4258 |
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diff
changeset
|
4259 <p> |
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|
4260 This function pops the value from the stack. |
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parents:
diff
changeset
|
4261 As in Lua, this function may trigger a metamethod |
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parents:
diff
changeset
|
4262 for the "newindex" event (see <a href="#2.4">§2.4</a>). |
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diff
changeset
|
4263 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
4264 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
4265 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
4266 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
4267 |
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|
4268 <hr><h3><a name="lua_setmetatable"><code>lua_setmetatable</code></a></h3><p> |
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|
4269 <span class="apii">[-1, +0, –]</span> |
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parents:
diff
changeset
|
4270 <pre>void lua_setmetatable (lua_State *L, int index);</pre> |
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diff
changeset
|
4271 |
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diff
changeset
|
4272 <p> |
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diff
changeset
|
4273 Pops a table from the stack and |
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diff
changeset
|
4274 sets it as the new metatable for the value at the given index. |
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diff
changeset
|
4275 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
4276 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
4277 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
4278 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
4279 |
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|
4280 <hr><h3><a name="lua_settable"><code>lua_settable</code></a></h3><p> |
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changeset
|
4281 <span class="apii">[-2, +0, <em>e</em>]</span> |
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|
4282 <pre>void lua_settable (lua_State *L, int index);</pre> |
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|
4283 |
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diff
changeset
|
4284 <p> |
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diff
changeset
|
4285 Does the equivalent to <code>t[k] = v</code>, |
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parents:
diff
changeset
|
4286 where <code>t</code> is the value at the given index, |
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changeset
|
4287 <code>v</code> is the value at the top of the stack, |
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changeset
|
4288 and <code>k</code> is the value just below the top. |
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changeset
|
4289 |
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diff
changeset
|
4290 |
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changeset
|
4291 <p> |
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diff
changeset
|
4292 This function pops both the key and the value from the stack. |
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diff
changeset
|
4293 As in Lua, this function may trigger a metamethod |
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changeset
|
4294 for the "newindex" event (see <a href="#2.4">§2.4</a>). |
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changeset
|
4295 |
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diff
changeset
|
4296 |
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diff
changeset
|
4297 |
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diff
changeset
|
4298 |
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diff
changeset
|
4299 |
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|
4300 <hr><h3><a name="lua_settop"><code>lua_settop</code></a></h3><p> |
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changeset
|
4301 <span class="apii">[-?, +?, –]</span> |
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changeset
|
4302 <pre>void lua_settop (lua_State *L, int index);</pre> |
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changeset
|
4303 |
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changeset
|
4304 <p> |
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|
4305 Accepts any index, or 0, |
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|
4306 and sets the stack top to this index. |
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changeset
|
4307 If the new top is larger than the old one, |
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changeset
|
4308 then the new elements are filled with <b>nil</b>. |
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|
4309 If <code>index</code> is 0, then all stack elements are removed. |
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changeset
|
4310 |
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diff
changeset
|
4311 |
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diff
changeset
|
4312 |
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diff
changeset
|
4313 |
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diff
changeset
|
4314 |
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changeset
|
4315 <hr><h3><a name="lua_setuservalue"><code>lua_setuservalue</code></a></h3><p> |
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changeset
|
4316 <span class="apii">[-1, +0, –]</span> |
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4317 <pre>void lua_setuservalue (lua_State *L, int index);</pre> |
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4318 |
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4319 <p> |
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4320 Pops a value from the stack and sets it as |
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4321 the new value associated to the userdata at the given index. |
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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_State"><code>lua_State</code></a></h3> |
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4328 <pre>typedef struct lua_State lua_State;</pre> |
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4329 |
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4330 <p> |
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4331 An opaque structure that points to a thread and indirectly |
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4332 (through the thread) to the whole state of a Lua interpreter. |
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4333 The Lua library is fully reentrant: |
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4334 it has no global variables. |
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4335 All information about a state is accessible through this structure. |
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4336 |
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4337 |
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4338 <p> |
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4339 A pointer to this structure must be passed as the first argument to |
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4340 every function in the library, except to <a href="#lua_newstate"><code>lua_newstate</code></a>, |
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4341 which creates a Lua state from scratch. |
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4342 |
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4343 |
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4344 |
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4345 |
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4346 |
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4347 <hr><h3><a name="lua_status"><code>lua_status</code></a></h3><p> |
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4348 <span class="apii">[-0, +0, –]</span> |
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4349 <pre>int lua_status (lua_State *L);</pre> |
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4350 |
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4351 <p> |
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4352 Returns the status of the thread <code>L</code>. |
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4353 |
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4354 |
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4355 <p> |
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4356 The status can be 0 (<a href="#pdf-LUA_OK"><code>LUA_OK</code></a>) for a normal thread, |
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4357 an error code if the thread finished the execution |
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4358 of a <a href="#lua_resume"><code>lua_resume</code></a> with an error, |
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4359 or <a name="pdf-LUA_YIELD"><code>LUA_YIELD</code></a> if the thread is suspended. |
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4360 |
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4361 |
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4362 <p> |
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4363 You can only call functions in threads with status <a href="#pdf-LUA_OK"><code>LUA_OK</code></a>. |
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4364 You can resume threads with status <a href="#pdf-LUA_OK"><code>LUA_OK</code></a> |
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4365 (to start a new coroutine) or <a href="#pdf-LUA_YIELD"><code>LUA_YIELD</code></a> |
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4366 (to resume a coroutine). |
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4367 |
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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 <hr><h3><a name="lua_stringtonumber"><code>lua_stringtonumber</code></a></h3><p> |
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4373 <span class="apii">[-0, +1, –]</span> |
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4374 <pre>size_t lua_stringtonumber (lua_State *L, const char *s);</pre> |
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4375 |
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4376 <p> |
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4377 Converts the zero-terminated string <code>s</code> to a number, |
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4378 pushes that number into the stack, |
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4379 and returns the total size of the string, |
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4380 that is, its length plus one. |
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4381 The conversion can result in an integer or a float, |
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4382 according to the lexical conventions of Lua (see <a href="#3.1">§3.1</a>). |
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4383 The string may have leading and trailing spaces and a sign. |
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4384 If the string is not a valid numeral, |
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4385 returns 0 and pushes nothing. |
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4386 (Note that the result can be used as a boolean, |
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4387 true if the conversion succeeds.) |
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|
4388 |
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4389 |
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4390 |
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|
4391 |
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4392 |
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4393 <hr><h3><a name="lua_toboolean"><code>lua_toboolean</code></a></h3><p> |
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4394 <span class="apii">[-0, +0, –]</span> |
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4395 <pre>int lua_toboolean (lua_State *L, int index);</pre> |
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|
4396 |
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|
4397 <p> |
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4398 Converts the Lua value at the given index to a C boolean |
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4399 value (0 or 1). |
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4400 Like all tests in Lua, |
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4401 <a href="#lua_toboolean"><code>lua_toboolean</code></a> returns true for any Lua value |
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4402 different from <b>false</b> and <b>nil</b>; |
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4403 otherwise it returns false. |
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|
4404 (If you want to accept only actual boolean values, |
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4405 use <a href="#lua_isboolean"><code>lua_isboolean</code></a> to test the value's type.) |
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4406 |
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4407 |
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4408 |
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4409 |
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4410 |
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4411 <hr><h3><a name="lua_tocfunction"><code>lua_tocfunction</code></a></h3><p> |
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4412 <span class="apii">[-0, +0, –]</span> |
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4413 <pre>lua_CFunction lua_tocfunction (lua_State *L, int index);</pre> |
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4414 |
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4415 <p> |
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4416 Converts a value at the given index to a C function. |
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4417 That value must be a C function; |
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4418 otherwise, returns <code>NULL</code>. |
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4419 |
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|
4420 |
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4421 |
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4422 |
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4423 |
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4424 <hr><h3><a name="lua_tointeger"><code>lua_tointeger</code></a></h3><p> |
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4425 <span class="apii">[-0, +0, –]</span> |
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4426 <pre>lua_Integer lua_tointeger (lua_State *L, int index);</pre> |
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4427 |
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4428 <p> |
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4429 Equivalent to <a href="#lua_tointegerx"><code>lua_tointegerx</code></a> with <code>isnum</code> equal to <code>NULL</code>. |
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4430 |
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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 <hr><h3><a name="lua_tointegerx"><code>lua_tointegerx</code></a></h3><p> |
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4436 <span class="apii">[-0, +0, –]</span> |
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4437 <pre>lua_Integer lua_tointegerx (lua_State *L, int index, int *isnum);</pre> |
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4438 |
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4439 <p> |
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4440 Converts the Lua value at the given index |
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|
4441 to the signed integral type <a href="#lua_Integer"><code>lua_Integer</code></a>. |
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4442 The Lua value must be an integer, |
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4443 or a number or string convertible to an integer (see <a href="#3.4.3">§3.4.3</a>); |
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4444 otherwise, <code>lua_tointegerx</code> returns 0. |
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4445 |
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4446 |
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4447 <p> |
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4448 If <code>isnum</code> is not <code>NULL</code>, |
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4449 its referent is assigned a boolean value that |
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4450 indicates whether the operation succeeded. |
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4451 |
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4452 |
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4453 |
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4454 |
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4455 |
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4456 <hr><h3><a name="lua_tolstring"><code>lua_tolstring</code></a></h3><p> |
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4457 <span class="apii">[-0, +0, <em>e</em>]</span> |
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4458 <pre>const char *lua_tolstring (lua_State *L, int index, size_t *len);</pre> |
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4459 |
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4460 <p> |
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4461 Converts the Lua value at the given index to a C string. |
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4462 If <code>len</code> is not <code>NULL</code>, |
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4463 it also sets <code>*len</code> with the string length. |
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4464 The Lua value must be a string or a number; |
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4465 otherwise, the function returns <code>NULL</code>. |
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4466 If the value is a number, |
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4467 then <code>lua_tolstring</code> also |
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4468 <em>changes the actual value in the stack to a string</em>. |
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4469 (This change confuses <a href="#lua_next"><code>lua_next</code></a> |
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4470 when <code>lua_tolstring</code> is applied to keys during a table traversal.) |
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4471 |
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|
4472 |
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4473 <p> |
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4474 <code>lua_tolstring</code> returns a fully aligned pointer |
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4475 to a string inside the Lua state. |
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4476 This string always has a zero ('<code>\0</code>') |
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4477 after its last character (as in C), |
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4478 but can contain other zeros in its body. |
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4479 |
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|
4480 |
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4481 <p> |
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4482 Because Lua has garbage collection, |
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4483 there is no guarantee that the pointer returned by <code>lua_tolstring</code> |
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4484 will be valid after the corresponding Lua value is removed from the stack. |
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|
4485 |
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|
4486 |
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|
4487 |
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|
4488 |
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4489 |
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4490 <hr><h3><a name="lua_tonumber"><code>lua_tonumber</code></a></h3><p> |
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4491 <span class="apii">[-0, +0, –]</span> |
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|
4492 <pre>lua_Number lua_tonumber (lua_State *L, int index);</pre> |
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4493 |
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|
4494 <p> |
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4495 Equivalent to <a href="#lua_tonumberx"><code>lua_tonumberx</code></a> with <code>isnum</code> equal to <code>NULL</code>. |
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|
4496 |
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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 <hr><h3><a name="lua_tonumberx"><code>lua_tonumberx</code></a></h3><p> |
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4502 <span class="apii">[-0, +0, –]</span> |
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|
4503 <pre>lua_Number lua_tonumberx (lua_State *L, int index, int *isnum);</pre> |
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|
4504 |
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4505 <p> |
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4506 Converts the Lua value at the given index |
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|
4507 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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4508 The Lua value must be a number or a string convertible to a number |
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|
4509 (see <a href="#3.4.3">§3.4.3</a>); |
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4510 otherwise, <a href="#lua_tonumberx"><code>lua_tonumberx</code></a> returns 0. |
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|
4511 |
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|
4512 |
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4513 <p> |
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4514 If <code>isnum</code> is not <code>NULL</code>, |
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4515 its referent is assigned a boolean value that |
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|
4516 indicates whether the operation succeeded. |
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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_topointer"><code>lua_topointer</code></a></h3><p> |
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4523 <span class="apii">[-0, +0, –]</span> |
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|
4524 <pre>const void *lua_topointer (lua_State *L, int index);</pre> |
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4525 |
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|
4526 <p> |
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4527 Converts the value at the given index to a generic |
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|
4528 C pointer (<code>void*</code>). |
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4529 The value can be a userdata, a table, a thread, or a function; |
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4530 otherwise, <code>lua_topointer</code> returns <code>NULL</code>. |
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4531 Different objects will give different pointers. |
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4532 There is no way to convert the pointer back to its original value. |
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4533 |
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|
4534 |
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4535 <p> |
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|
4536 Typically this function is used only for debug information. |
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|
4537 |
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|
4538 |
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|
4539 |
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4540 |
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4541 |
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4542 <hr><h3><a name="lua_tostring"><code>lua_tostring</code></a></h3><p> |
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4543 <span class="apii">[-0, +0, <em>e</em>]</span> |
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4544 <pre>const char *lua_tostring (lua_State *L, int index);</pre> |
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4545 |
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4546 <p> |
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|
4547 Equivalent to <a href="#lua_tolstring"><code>lua_tolstring</code></a> with <code>len</code> equal to <code>NULL</code>. |
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4548 |
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4549 |
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4550 |
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4551 |
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4552 |
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4553 <hr><h3><a name="lua_tothread"><code>lua_tothread</code></a></h3><p> |
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4554 <span class="apii">[-0, +0, –]</span> |
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4555 <pre>lua_State *lua_tothread (lua_State *L, int index);</pre> |
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4556 |
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4557 <p> |
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4558 Converts the value at the given index to a Lua thread |
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4559 (represented as <code>lua_State*</code>). |
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4560 This value must be a thread; |
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4561 otherwise, the function returns <code>NULL</code>. |
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4562 |
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|
4563 |
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|
4564 |
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|
4565 |
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|
4566 |
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4567 <hr><h3><a name="lua_touserdata"><code>lua_touserdata</code></a></h3><p> |
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4568 <span class="apii">[-0, +0, –]</span> |
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|
4569 <pre>void *lua_touserdata (lua_State *L, int index);</pre> |
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|
4570 |
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|
4571 <p> |
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4572 If the value at the given index is a full userdata, |
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|
4573 returns its block address. |
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4574 If the value is a light userdata, |
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|
4575 returns its pointer. |
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|
4576 Otherwise, returns <code>NULL</code>. |
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|
4577 |
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|
4578 |
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diff
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|
4579 |
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|
4580 |
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diff
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|
4581 |
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4582 <hr><h3><a name="lua_type"><code>lua_type</code></a></h3><p> |
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|
4583 <span class="apii">[-0, +0, –]</span> |
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|
4584 <pre>int lua_type (lua_State *L, int index);</pre> |
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|
4585 |
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|
4586 <p> |
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|
4587 Returns the type of the value in the given valid index, |
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|
4588 or <code>LUA_TNONE</code> for a non-valid (but acceptable) index. |
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4589 The types returned by <a href="#lua_type"><code>lua_type</code></a> are coded by the following constants |
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|
4590 defined in <code>lua.h</code>: |
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|
4591 <a name="pdf-LUA_TNIL"><code>LUA_TNIL</code></a>, |
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|
4592 <a name="pdf-LUA_TNUMBER"><code>LUA_TNUMBER</code></a>, |
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|
4593 <a name="pdf-LUA_TBOOLEAN"><code>LUA_TBOOLEAN</code></a>, |
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|
4594 <a name="pdf-LUA_TSTRING"><code>LUA_TSTRING</code></a>, |
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|
4595 <a name="pdf-LUA_TTABLE"><code>LUA_TTABLE</code></a>, |
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|
4596 <a name="pdf-LUA_TFUNCTION"><code>LUA_TFUNCTION</code></a>, |
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|
4597 <a name="pdf-LUA_TUSERDATA"><code>LUA_TUSERDATA</code></a>, |
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|
4598 <a name="pdf-LUA_TTHREAD"><code>LUA_TTHREAD</code></a>, |
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|
4599 and |
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|
4600 <a name="pdf-LUA_TLIGHTUSERDATA"><code>LUA_TLIGHTUSERDATA</code></a>. |
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|
4601 |
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|
4602 |
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|
4603 |
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|
4604 |
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|
4605 |
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|
4606 <hr><h3><a name="lua_typename"><code>lua_typename</code></a></h3><p> |
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4607 <span class="apii">[-0, +0, –]</span> |
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|
4608 <pre>const char *lua_typename (lua_State *L, int tp);</pre> |
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|
4609 |
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|
4610 <p> |
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|
4611 Returns the name of the type encoded by the value <code>tp</code>, |
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|
4612 which must be one the values returned by <a href="#lua_type"><code>lua_type</code></a>. |
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|
4613 |
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|
4614 |
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|
4615 |
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|
4616 |
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|
4617 |
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|
4618 <hr><h3><a name="lua_Unsigned"><code>lua_Unsigned</code></a></h3> |
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|
4619 <pre>typedef ... lua_Unsigned;</pre> |
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|
4620 |
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|
4621 <p> |
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|
4622 The unsigned version of <a href="#lua_Integer"><code>lua_Integer</code></a>. |
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|
4623 |
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|
4624 |
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|
4625 |
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|
4626 |
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|
4627 |
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|
4628 <hr><h3><a name="lua_upvalueindex"><code>lua_upvalueindex</code></a></h3><p> |
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4629 <span class="apii">[-0, +0, –]</span> |
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|
4630 <pre>int lua_upvalueindex (int i);</pre> |
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|
4631 |
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|
4632 <p> |
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|
4633 Returns the pseudo-index that represents the <code>i</code>-th upvalue of |
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|
4634 the running function (see <a href="#4.4">§4.4</a>). |
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|
4635 |
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|
4636 |
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|
4637 |
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|
4638 |
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|
4639 |
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4640 <hr><h3><a name="lua_version"><code>lua_version</code></a></h3><p> |
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|
4641 <span class="apii">[-0, +0, <em>v</em>]</span> |
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|
4642 <pre>const lua_Number *lua_version (lua_State *L);</pre> |
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|
4643 |
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|
4644 <p> |
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4645 Returns the address of the version number stored in the Lua core. |
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|
4646 When called with a valid <a href="#lua_State"><code>lua_State</code></a>, |
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4647 returns the address of the version used to create that state. |
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4648 When called with <code>NULL</code>, |
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4649 returns the address of the version running the call. |
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|
4650 |
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|
4651 |
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|
4652 |
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|
4653 |
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|
4654 |
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4655 <hr><h3><a name="lua_Writer"><code>lua_Writer</code></a></h3> |
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4656 <pre>typedef int (*lua_Writer) (lua_State *L, |
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4657 const void* p, |
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4658 size_t sz, |
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4659 void* ud);</pre> |
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4660 |
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|
4661 <p> |
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4662 The type of the writer function used by <a href="#lua_dump"><code>lua_dump</code></a>. |
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4663 Every time it produces another piece of chunk, |
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4664 <a href="#lua_dump"><code>lua_dump</code></a> calls the writer, |
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4665 passing along the buffer to be written (<code>p</code>), |
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4666 its size (<code>sz</code>), |
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4667 and the <code>data</code> parameter supplied to <a href="#lua_dump"><code>lua_dump</code></a>. |
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4668 |
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|
4669 |
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4670 <p> |
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4671 The writer returns an error code: |
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4672 0 means no errors; |
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4673 any other value means an error and stops <a href="#lua_dump"><code>lua_dump</code></a> from |
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4674 calling the writer again. |
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4675 |
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4676 |
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4677 |
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|
4678 |
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|
4679 |
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4680 <hr><h3><a name="lua_xmove"><code>lua_xmove</code></a></h3><p> |
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4681 <span class="apii">[-?, +?, –]</span> |
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4682 <pre>void lua_xmove (lua_State *from, lua_State *to, int n);</pre> |
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4683 |
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4684 <p> |
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4685 Exchange values between different threads of the same state. |
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|
4686 |
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|
4687 |
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4688 <p> |
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4689 This function pops <code>n</code> values from the stack <code>from</code>, |
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4690 and pushes them onto the stack <code>to</code>. |
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4691 |
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|
4692 |
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|
4693 |
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|
4694 |
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4695 |
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4696 <hr><h3><a name="lua_yield"><code>lua_yield</code></a></h3><p> |
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4697 <span class="apii">[-?, +?, <em>e</em>]</span> |
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4698 <pre>int lua_yield (lua_State *L, int nresults);</pre> |
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4699 |
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4700 <p> |
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4701 This function is equivalent to <a href="#lua_yieldk"><code>lua_yieldk</code></a>, |
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4702 but it has no continuation (see <a href="#4.7">§4.7</a>). |
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4703 Therefore, when the thread resumes, |
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4704 it continues the function that called |
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4705 the function calling <code>lua_yield</code>. |
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4706 |
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|
4707 |
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|
4708 |
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4709 |
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|
4710 |
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|
4711 <hr><h3><a name="lua_yieldk"><code>lua_yieldk</code></a></h3><p> |
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4712 <span class="apii">[-?, +?, <em>e</em>]</span> |
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4713 <pre>int lua_yieldk (lua_State *L, |
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4714 int nresults, |
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4715 lua_KContext ctx, |
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|
4716 lua_KFunction k);</pre> |
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4717 |
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|
4718 <p> |
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4719 Yields a coroutine (thread). |
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|
4720 |
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|
4721 |
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|
4722 <p> |
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4723 When a C function calls <a href="#lua_yieldk"><code>lua_yieldk</code></a>, |
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4724 the running coroutine suspends its execution, |
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4725 and the call to <a href="#lua_resume"><code>lua_resume</code></a> that started this coroutine returns. |
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|
4726 The parameter <code>nresults</code> is the number of values from the stack |
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|
4727 that will be passed as results to <a href="#lua_resume"><code>lua_resume</code></a>. |
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|
4728 |
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|
4729 |
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|
4730 <p> |
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|
4731 When the coroutine is resumed again, |
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4732 Lua calls the given continuation function <code>k</code> to continue |
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|
4733 the execution of the C function that yielded (see <a href="#4.7">§4.7</a>). |
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4734 This continuation function receives the same stack |
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4735 from the previous function, |
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|
4736 with the <code>n</code> results removed and |
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|
4737 replaced by the arguments passed to <a href="#lua_resume"><code>lua_resume</code></a>. |
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4738 Moreover, |
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4739 the continuation function receives the value <code>ctx</code> |
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|
4740 that was passed to <a href="#lua_yieldk"><code>lua_yieldk</code></a>. |
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|
4741 |
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|
4742 |
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|
4743 <p> |
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|
4744 Usually, this function does not return; |
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|
4745 when the coroutine eventually resumes, |
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|
4746 it continues executing the continuation function. |
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|
4747 However, there is one special case, |
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|
4748 which is when this function is called |
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|
4749 from inside a line hook (see <a href="#4.9">§4.9</a>). |
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|
4750 In that case, <code>lua_yieldk</code> should be called with no continuation |
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|
4751 (probably in the form of <a href="#lua_yield"><code>lua_yield</code></a>), |
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4752 and the hook should return immediately after the call. |
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|
4753 Lua will yield and, |
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|
4754 when the coroutine resumes again, |
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|
4755 it will continue the normal execution |
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|
4756 of the (Lua) function that triggered the hook. |
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|
4757 |
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|
4758 |
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|
4759 <p> |
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|
4760 This function can raise an error if it is called from a thread |
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|
4761 with a pending C call with no continuation function, |
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|
4762 or it is called from a thread that is not running inside a resume |
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|
4763 (e.g., the main thread). |
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|
4764 |
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|
4765 |
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|
4766 |
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|
4767 |
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|
4768 |
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|
4769 |
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|
4770 |
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|
4771 <h2>4.9 – <a name="4.9">The Debug Interface</a></h2> |
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|
4772 |
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|
4773 <p> |
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|
4774 Lua has no built-in debugging facilities. |
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|
4775 Instead, it offers a special interface |
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|
4776 by means of functions and <em>hooks</em>. |
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4777 This interface allows the construction of different |
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|
4778 kinds of debuggers, profilers, and other tools |
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|
4779 that need "inside information" from the interpreter. |
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|
4780 |
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|
4781 |
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|
4782 |
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|
4783 <hr><h3><a name="lua_Debug"><code>lua_Debug</code></a></h3> |
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|
4784 <pre>typedef struct lua_Debug { |
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|
4785 int event; |
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|
4786 const char *name; /* (n) */ |
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|
4787 const char *namewhat; /* (n) */ |
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|
4788 const char *what; /* (S) */ |
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|
4789 const char *source; /* (S) */ |
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|
4790 int currentline; /* (l) */ |
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|
4791 int linedefined; /* (S) */ |
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|
4792 int lastlinedefined; /* (S) */ |
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4793 unsigned char nups; /* (u) number of upvalues */ |
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4794 unsigned char nparams; /* (u) number of parameters */ |
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|
4795 char isvararg; /* (u) */ |
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4796 char istailcall; /* (t) */ |
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4797 char short_src[LUA_IDSIZE]; /* (S) */ |
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4798 /* private part */ |
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|
4799 <em>other fields</em> |
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|
4800 } lua_Debug;</pre> |
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|
4801 |
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4802 <p> |
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4803 A structure used to carry different pieces of |
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4804 information about a function or an activation record. |
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4805 <a href="#lua_getstack"><code>lua_getstack</code></a> fills only the private part |
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4806 of this structure, for later use. |
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4807 To fill the other fields of <a href="#lua_Debug"><code>lua_Debug</code></a> with useful information, |
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4808 call <a href="#lua_getinfo"><code>lua_getinfo</code></a>. |
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4809 |
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|
4810 |
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4811 <p> |
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4812 The fields of <a href="#lua_Debug"><code>lua_Debug</code></a> have the following meaning: |
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4813 |
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4814 <ul> |
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|
4815 |
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4816 <li><b><code>source</code>: </b> |
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4817 the name of the chunk that created the function. |
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4818 If <code>source</code> starts with a '<code>@</code>', |
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4819 it means that the function was defined in a file where |
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4820 the file name follows the '<code>@</code>'. |
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4821 If <code>source</code> starts with a '<code>=</code>', |
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4822 the remainder of its contents describe the source in a user-dependent manner. |
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4823 Otherwise, |
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4824 the function was defined in a string where |
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4825 <code>source</code> is that string. |
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4826 </li> |
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|
4827 |
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4828 <li><b><code>short_src</code>: </b> |
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4829 a "printable" version of <code>source</code>, to be used in error messages. |
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4830 </li> |
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|
4831 |
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4832 <li><b><code>linedefined</code>: </b> |
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4833 the line number where the definition of the function starts. |
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|
4834 </li> |
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|
4835 |
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|
4836 <li><b><code>lastlinedefined</code>: </b> |
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4837 the line number where the definition of the function ends. |
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|
4838 </li> |
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|
4839 |
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4840 <li><b><code>what</code>: </b> |
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|
4841 the string <code>"Lua"</code> if the function is a Lua function, |
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4842 <code>"C"</code> if it is a C function, |
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|
4843 <code>"main"</code> if it is the main part of a chunk. |
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|
4844 </li> |
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|
4845 |
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|
4846 <li><b><code>currentline</code>: </b> |
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|
4847 the current line where the given function is executing. |
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4848 When no line information is available, |
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4849 <code>currentline</code> is set to -1. |
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|
4850 </li> |
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|
4851 |
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4852 <li><b><code>name</code>: </b> |
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4853 a reasonable name for the given function. |
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4854 Because functions in Lua are first-class values, |
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4855 they do not have a fixed name: |
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4856 some functions can be the value of multiple global variables, |
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4857 while others can be stored only in a table field. |
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|
4858 The <code>lua_getinfo</code> function checks how the function was |
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4859 called to find a suitable name. |
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|
4860 If it cannot find a name, |
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|
4861 then <code>name</code> is set to <code>NULL</code>. |
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|
4862 </li> |
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|
4863 |
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|
4864 <li><b><code>namewhat</code>: </b> |
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|
4865 explains the <code>name</code> field. |
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|
4866 The value of <code>namewhat</code> can be |
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|
4867 <code>"global"</code>, <code>"local"</code>, <code>"method"</code>, |
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|
4868 <code>"field"</code>, <code>"upvalue"</code>, or <code>""</code> (the empty string), |
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|
4869 according to how the function was called. |
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|
4870 (Lua uses the empty string when no other option seems to apply.) |
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|
4871 </li> |
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|
4872 |
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|
4873 <li><b><code>istailcall</code>: </b> |
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|
4874 true if this function invocation was called by a tail call. |
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|
4875 In this case, the caller of this level is not in the stack. |
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|
4876 </li> |
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|
4877 |
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|
4878 <li><b><code>nups</code>: </b> |
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|
4879 the number of upvalues of the function. |
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|
4880 </li> |
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|
4881 |
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|
4882 <li><b><code>nparams</code>: </b> |
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4883 the number of fixed parameters of the function |
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|
4884 (always 0 for C functions). |
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|
4885 </li> |
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|
4886 |
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|
4887 <li><b><code>isvararg</code>: </b> |
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|
4888 true if the function is a vararg function |
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|
4889 (always true for C functions). |
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|
4890 </li> |
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|
4891 |
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|
4892 </ul> |
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|
4893 |
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|
4894 |
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|
4895 |
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|
4896 |
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|
4897 <hr><h3><a name="lua_gethook"><code>lua_gethook</code></a></h3><p> |
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|
4898 <span class="apii">[-0, +0, –]</span> |
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|
4899 <pre>lua_Hook lua_gethook (lua_State *L);</pre> |
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|
4900 |
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|
4901 <p> |
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|
4902 Returns the current hook function. |
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|
4903 |
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|
4904 |
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|
4905 |
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|
4906 |
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|
4907 |
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|
4908 <hr><h3><a name="lua_gethookcount"><code>lua_gethookcount</code></a></h3><p> |
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4909 <span class="apii">[-0, +0, –]</span> |
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|
4910 <pre>int lua_gethookcount (lua_State *L);</pre> |
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4911 |
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|
4912 <p> |
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4913 Returns the current hook count. |
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|
4914 |
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4915 |
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|
4916 |
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|
4917 |
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4918 |
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|
4919 <hr><h3><a name="lua_gethookmask"><code>lua_gethookmask</code></a></h3><p> |
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4920 <span class="apii">[-0, +0, –]</span> |
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|
4921 <pre>int lua_gethookmask (lua_State *L);</pre> |
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4922 |
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4923 <p> |
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4924 Returns the current hook mask. |
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4925 |
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4926 |
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4927 |
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4928 |
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4929 |
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4930 <hr><h3><a name="lua_getinfo"><code>lua_getinfo</code></a></h3><p> |
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4931 <span class="apii">[-(0|1), +(0|1|2), <em>e</em>]</span> |
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4932 <pre>int lua_getinfo (lua_State *L, const char *what, lua_Debug *ar);</pre> |
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4933 |
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4934 <p> |
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4935 Gets information about a specific function or function invocation. |
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4936 |
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4937 |
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4938 <p> |
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4939 To get information about a function invocation, |
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4940 the parameter <code>ar</code> must be a valid activation record that was |
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4941 filled by a previous call to <a href="#lua_getstack"><code>lua_getstack</code></a> or |
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4942 given as argument to a hook (see <a href="#lua_Hook"><code>lua_Hook</code></a>). |
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4943 |
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4944 |
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4945 <p> |
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4946 To get information about a function you push it onto the stack |
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4947 and start the <code>what</code> string with the character '<code>></code>'. |
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4948 (In that case, |
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4949 <code>lua_getinfo</code> pops the function from the top of the stack.) |
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4950 For instance, to know in which line a function <code>f</code> was defined, |
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4951 you can write the following code: |
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4952 |
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4953 <pre> |
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4954 lua_Debug ar; |
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4955 lua_getglobal(L, "f"); /* get global 'f' */ |
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4956 lua_getinfo(L, ">S", &ar); |
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4957 printf("%d\n", ar.linedefined); |
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4958 </pre> |
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4959 |
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4960 <p> |
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4961 Each character in the string <code>what</code> |
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4962 selects some fields of the structure <code>ar</code> to be filled or |
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4963 a value to be pushed on the stack: |
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4964 |
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4965 <ul> |
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4966 |
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4967 <li><b>'<code>n</code>': </b> fills in the field <code>name</code> and <code>namewhat</code>; |
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4968 </li> |
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4969 |
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4970 <li><b>'<code>S</code>': </b> |
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4971 fills in the fields <code>source</code>, <code>short_src</code>, |
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4972 <code>linedefined</code>, <code>lastlinedefined</code>, and <code>what</code>; |
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4973 </li> |
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4974 |
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4975 <li><b>'<code>l</code>': </b> fills in the field <code>currentline</code>; |
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4976 </li> |
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4977 |
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4978 <li><b>'<code>t</code>': </b> fills in the field <code>istailcall</code>; |
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4979 </li> |
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4980 |
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4981 <li><b>'<code>u</code>': </b> fills in the fields |
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4982 <code>nups</code>, <code>nparams</code>, and <code>isvararg</code>; |
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4983 </li> |
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4984 |
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4985 <li><b>'<code>f</code>': </b> |
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4986 pushes onto the stack the function that is |
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4987 running at the given level; |
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4988 </li> |
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4989 |
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4990 <li><b>'<code>L</code>': </b> |
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4991 pushes onto the stack a table whose indices are the |
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4992 numbers of the lines that are valid on the function. |
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4993 (A <em>valid line</em> is a line with some associated code, |
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4994 that is, a line where you can put a break point. |
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4995 Non-valid lines include empty lines and comments.) |
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4996 |
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4997 |
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4998 <p> |
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4999 If this option is given together with option '<code>f</code>', |
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5000 its table is pushed after the function. |
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5001 </li> |
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|
5002 |
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5003 </ul> |
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5004 |
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5005 <p> |
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5006 This function returns 0 on error |
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5007 (for instance, an invalid option in <code>what</code>). |
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5008 |
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5009 |
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5010 |
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5011 |
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5012 |
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5013 <hr><h3><a name="lua_getlocal"><code>lua_getlocal</code></a></h3><p> |
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5014 <span class="apii">[-0, +(0|1), –]</span> |
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5015 <pre>const char *lua_getlocal (lua_State *L, const lua_Debug *ar, int n);</pre> |
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5016 |
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5017 <p> |
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5018 Gets information about a local variable of |
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5019 a given activation record or a given function. |
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5020 |
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5021 |
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5022 <p> |
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5023 In the first case, |
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5024 the parameter <code>ar</code> must be a valid activation record that was |
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5025 filled by a previous call to <a href="#lua_getstack"><code>lua_getstack</code></a> or |
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5026 given as argument to a hook (see <a href="#lua_Hook"><code>lua_Hook</code></a>). |
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5027 The index <code>n</code> selects which local variable to inspect; |
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5028 see <a href="#pdf-debug.getlocal"><code>debug.getlocal</code></a> for details about variable indices |
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5029 and names. |
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5030 |
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5031 |
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5032 <p> |
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5033 <a href="#lua_getlocal"><code>lua_getlocal</code></a> pushes the variable's value onto the stack |
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5034 and returns its name. |
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5035 |
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5036 |
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5037 <p> |
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5038 In the second case, <code>ar</code> must be <code>NULL</code> and the function |
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5039 to be inspected must be at the top of the stack. |
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5040 In this case, only parameters of Lua functions are visible |
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5041 (as there is no information about what variables are active) |
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5042 and no values are pushed onto the stack. |
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5043 |
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5044 |
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5045 <p> |
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5046 Returns <code>NULL</code> (and pushes nothing) |
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5047 when the index is greater than |
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5048 the number of active local variables. |
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5049 |
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5050 |
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5051 |
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5052 |
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5053 |
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5054 <hr><h3><a name="lua_getstack"><code>lua_getstack</code></a></h3><p> |
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5055 <span class="apii">[-0, +0, –]</span> |
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5056 <pre>int lua_getstack (lua_State *L, int level, lua_Debug *ar);</pre> |
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5057 |
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5058 <p> |
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5059 Gets information about the interpreter runtime stack. |
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5060 |
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5061 |
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5062 <p> |
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5063 This function fills parts of a <a href="#lua_Debug"><code>lua_Debug</code></a> structure with |
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5064 an identification of the <em>activation record</em> |
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5065 of the function executing at a given level. |
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5066 Level 0 is the current running function, |
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5067 whereas level <em>n+1</em> is the function that has called level <em>n</em> |
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5068 (except for tail calls, which do not count on the stack). |
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5069 When there are no errors, <a href="#lua_getstack"><code>lua_getstack</code></a> returns 1; |
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5070 when called with a level greater than the stack depth, |
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5071 it returns 0. |
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5072 |
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5073 |
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5074 |
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5075 |
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5076 |
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5077 <hr><h3><a name="lua_getupvalue"><code>lua_getupvalue</code></a></h3><p> |
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5078 <span class="apii">[-0, +(0|1), –]</span> |
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5079 <pre>const char *lua_getupvalue (lua_State *L, int funcindex, int n);</pre> |
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5080 |
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5081 <p> |
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5082 Gets information about a closure's upvalue. |
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5083 (For Lua functions, |
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5084 upvalues are the external local variables that the function uses, |
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5085 and that are consequently included in its closure.) |
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5086 <a href="#lua_getupvalue"><code>lua_getupvalue</code></a> gets the index <code>n</code> of an upvalue, |
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5087 pushes the upvalue's value onto the stack, |
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5088 and returns its name. |
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5089 <code>funcindex</code> points to the closure in the stack. |
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5090 (Upvalues have no particular order, |
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5091 as they are active through the whole function. |
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5092 So, they are numbered in an arbitrary order.) |
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5093 |
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|
5094 |
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5095 <p> |
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5096 Returns <code>NULL</code> (and pushes nothing) |
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5097 when the index is greater than the number of upvalues. |
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5098 For C functions, this function uses the empty string <code>""</code> |
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5099 as a name for all upvalues. |
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5100 |
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5101 |
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5102 |
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5103 |
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5104 |
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5105 <hr><h3><a name="lua_Hook"><code>lua_Hook</code></a></h3> |
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5106 <pre>typedef void (*lua_Hook) (lua_State *L, lua_Debug *ar);</pre> |
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5107 |
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5108 <p> |
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5109 Type for debugging hook functions. |
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5110 |
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|
5111 |
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5112 <p> |
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5113 Whenever a hook is called, its <code>ar</code> argument has its field |
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5114 <code>event</code> set to the specific event that triggered the hook. |
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5115 Lua identifies these events with the following constants: |
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5116 <a name="pdf-LUA_HOOKCALL"><code>LUA_HOOKCALL</code></a>, <a name="pdf-LUA_HOOKRET"><code>LUA_HOOKRET</code></a>, |
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5117 <a name="pdf-LUA_HOOKTAILCALL"><code>LUA_HOOKTAILCALL</code></a>, <a name="pdf-LUA_HOOKLINE"><code>LUA_HOOKLINE</code></a>, |
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5118 and <a name="pdf-LUA_HOOKCOUNT"><code>LUA_HOOKCOUNT</code></a>. |
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5119 Moreover, for line events, the field <code>currentline</code> is also set. |
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5120 To get the value of any other field in <code>ar</code>, |
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5121 the hook must call <a href="#lua_getinfo"><code>lua_getinfo</code></a>. |
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5122 |
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5123 |
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5124 <p> |
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5125 For call events, <code>event</code> can be <code>LUA_HOOKCALL</code>, |
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5126 the normal value, or <code>LUA_HOOKTAILCALL</code>, for a tail call; |
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5127 in this case, there will be no corresponding return event. |
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5128 |
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5129 |
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5130 <p> |
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5131 While Lua is running a hook, it disables other calls to hooks. |
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5132 Therefore, if a hook calls back Lua to execute a function or a chunk, |
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5133 this execution occurs without any calls to hooks. |
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|
5134 |
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5135 |
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5136 <p> |
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5137 Hook functions cannot have continuations, |
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5138 that is, they cannot call <a href="#lua_yieldk"><code>lua_yieldk</code></a>, |
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5139 <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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5140 |
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5141 |
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5142 <p> |
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5143 Hook functions can yield under the following conditions: |
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5144 Only count and line events can yield |
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5145 and they cannot yield any value; |
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5146 to yield a hook function must finish its execution |
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5147 calling <a href="#lua_yield"><code>lua_yield</code></a> with <code>nresults</code> equal to zero. |
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5148 |
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5149 |
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5150 |
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5151 |
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5152 |
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5153 <hr><h3><a name="lua_sethook"><code>lua_sethook</code></a></h3><p> |
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5154 <span class="apii">[-0, +0, –]</span> |
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5155 <pre>void lua_sethook (lua_State *L, lua_Hook f, int mask, int count);</pre> |
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5156 |
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5157 <p> |
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5158 Sets the debugging hook function. |
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5159 |
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5160 |
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5161 <p> |
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5162 Argument <code>f</code> is the hook function. |
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5163 <code>mask</code> specifies on which events the hook will be called: |
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5164 it is formed by a bitwise or of the constants |
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5165 <a name="pdf-LUA_MASKCALL"><code>LUA_MASKCALL</code></a>, |
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5166 <a name="pdf-LUA_MASKRET"><code>LUA_MASKRET</code></a>, |
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5167 <a name="pdf-LUA_MASKLINE"><code>LUA_MASKLINE</code></a>, |
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5168 and <a name="pdf-LUA_MASKCOUNT"><code>LUA_MASKCOUNT</code></a>. |
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5169 The <code>count</code> argument is only meaningful when the mask |
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5170 includes <code>LUA_MASKCOUNT</code>. |
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5171 For each event, the hook is called as explained below: |
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5172 |
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5173 <ul> |
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5174 |
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5175 <li><b>The call hook: </b> is called when the interpreter calls a function. |
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5176 The hook is called just after Lua enters the new function, |
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5177 before the function gets its arguments. |
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5178 </li> |
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5179 |
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5180 <li><b>The return hook: </b> is called when the interpreter returns from a function. |
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5181 The hook is called just before Lua leaves the function. |
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5182 There is no standard way to access the values |
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5183 to be returned by the function. |
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5184 </li> |
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5185 |
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5186 <li><b>The line hook: </b> is called when the interpreter is about to |
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5187 start the execution of a new line of code, |
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5188 or when it jumps back in the code (even to the same line). |
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5189 (This event only happens while Lua is executing a Lua function.) |
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5190 </li> |
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5191 |
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5192 <li><b>The count hook: </b> is called after the interpreter executes every |
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5193 <code>count</code> instructions. |
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5194 (This event only happens while Lua is executing a Lua function.) |
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5195 </li> |
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5196 |
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5197 </ul> |
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5198 |
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5199 <p> |
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5200 A hook is disabled by setting <code>mask</code> to zero. |
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5201 |
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5202 |
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5203 |
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5204 |
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5205 |
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5206 <hr><h3><a name="lua_setlocal"><code>lua_setlocal</code></a></h3><p> |
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5207 <span class="apii">[-(0|1), +0, –]</span> |
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5208 <pre>const char *lua_setlocal (lua_State *L, const lua_Debug *ar, int n);</pre> |
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5209 |
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5210 <p> |
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5211 Sets the value of a local variable of a given activation record. |
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5212 Parameters <code>ar</code> and <code>n</code> are as in <a href="#lua_getlocal"><code>lua_getlocal</code></a> |
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5213 (see <a href="#lua_getlocal"><code>lua_getlocal</code></a>). |
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5214 <a href="#lua_setlocal"><code>lua_setlocal</code></a> assigns the value at the top of the stack |
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5215 to the variable and returns its name. |
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5216 It also pops the value from the stack. |
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5217 |
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5218 |
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5219 <p> |
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5220 Returns <code>NULL</code> (and pops nothing) |
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5221 when the index is greater than |
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5222 the number of active local variables. |
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5223 |
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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 <hr><h3><a name="lua_setupvalue"><code>lua_setupvalue</code></a></h3><p> |
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5229 <span class="apii">[-(0|1), +0, –]</span> |
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5230 <pre>const char *lua_setupvalue (lua_State *L, int funcindex, int n);</pre> |
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5231 |
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5232 <p> |
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5233 Sets the value of a closure's upvalue. |
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5234 It assigns the value at the top of the stack |
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5235 to the upvalue and returns its name. |
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5236 It also pops the value from the stack. |
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5237 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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5238 (see <a href="#lua_getupvalue"><code>lua_getupvalue</code></a>). |
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5239 |
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5240 |
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5241 <p> |
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5242 Returns <code>NULL</code> (and pops nothing) |
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5243 when the index is greater than the number of upvalues. |
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5244 |
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|
5245 |
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5246 |
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5247 |
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5248 |
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5249 <hr><h3><a name="lua_upvalueid"><code>lua_upvalueid</code></a></h3><p> |
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5250 <span class="apii">[-0, +0, –]</span> |
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5251 <pre>void *lua_upvalueid (lua_State *L, int funcindex, int n);</pre> |
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5252 |
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5253 <p> |
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5254 Returns a unique identifier for the upvalue numbered <code>n</code> |
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5255 from the closure at index <code>funcindex</code>. |
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5256 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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5257 (see <a href="#lua_getupvalue"><code>lua_getupvalue</code></a>) |
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5258 (but <code>n</code> cannot be greater than the number of upvalues). |
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5259 |
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5260 |
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5261 <p> |
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5262 These unique identifiers allow a program to check whether different |
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5263 closures share upvalues. |
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5264 Lua closures that share an upvalue |
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5265 (that is, that access a same external local variable) |
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5266 will return identical ids for those upvalue indices. |
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5267 |
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5268 |
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5269 |
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5270 |
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5271 |
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5272 <hr><h3><a name="lua_upvaluejoin"><code>lua_upvaluejoin</code></a></h3><p> |
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5273 <span class="apii">[-0, +0, –]</span> |
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5274 <pre>void lua_upvaluejoin (lua_State *L, int funcindex1, int n1, |
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5275 int funcindex2, int n2);</pre> |
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5276 |
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5277 <p> |
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5278 Make the <code>n1</code>-th upvalue of the Lua closure at index <code>funcindex1</code> |
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5279 refer to the <code>n2</code>-th upvalue of the Lua closure at index <code>funcindex2</code>. |
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5280 |
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5281 |
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5282 |
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|
5283 |
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5284 |
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|
5285 |
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5286 |
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|
5287 <h1>5 – <a name="5">The Auxiliary Library</a></h1> |
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5288 |
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5289 <p> |
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|
5290 |
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5291 The <em>auxiliary library</em> provides several convenient functions |
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5292 to interface C with Lua. |
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5293 While the basic API provides the primitive functions for all |
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5294 interactions between C and Lua, |
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5295 the auxiliary library provides higher-level functions for some |
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5296 common tasks. |
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5297 |
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5298 |
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5299 <p> |
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5300 All functions and types from the auxiliary library |
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5301 are defined in header file <code>lauxlib.h</code> and |
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5302 have a prefix <code>luaL_</code>. |
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5303 |
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5304 |
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5305 <p> |
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5306 All functions in the auxiliary library are built on |
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5307 top of the basic API, |
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5308 and so they provide nothing that cannot be done with that API. |
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5309 Nevertheless, the use of the auxiliary library ensures |
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5310 more consistency to your code. |
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5311 |
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5312 |
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5313 <p> |
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5314 Several functions in the auxiliary library use internally some |
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5315 extra stack slots. |
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5316 When a function in the auxiliary library uses less than five slots, |
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5317 it does not check the stack size; |
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5318 it simply assumes that there are enough slots. |
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5319 |
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|
5320 |
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5321 <p> |
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5322 Several functions in the auxiliary library are used to |
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5323 check C function arguments. |
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|
5324 Because the error message is formatted for arguments |
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5325 (e.g., "<code>bad argument #1</code>"), |
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5326 you should not use these functions for other stack values. |
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|
5327 |
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|
5328 |
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|
5329 <p> |
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5330 Functions called <code>luaL_check*</code> |
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5331 always raise an error if the check is not satisfied. |
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5332 |
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|
5333 |
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|
5334 |
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|
5335 <h2>5.1 – <a name="5.1">Functions and Types</a></h2> |
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5336 |
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5337 <p> |
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5338 Here we list all functions and types from the auxiliary library |
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|
5339 in alphabetical order. |
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|
5340 |
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|
5341 |
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5342 |
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5343 <hr><h3><a name="luaL_addchar"><code>luaL_addchar</code></a></h3><p> |
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5344 <span class="apii">[-?, +?, <em>e</em>]</span> |
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|
5345 <pre>void luaL_addchar (luaL_Buffer *B, char c);</pre> |
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5346 |
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5347 <p> |
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5348 Adds the byte <code>c</code> to the buffer <code>B</code> |
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5349 (see <a href="#luaL_Buffer"><code>luaL_Buffer</code></a>). |
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|
5350 |
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|
5351 |
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|
5352 |
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|
5353 |
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|
5354 |
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5355 <hr><h3><a name="luaL_addlstring"><code>luaL_addlstring</code></a></h3><p> |
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5356 <span class="apii">[-?, +?, <em>e</em>]</span> |
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|
5357 <pre>void luaL_addlstring (luaL_Buffer *B, const char *s, size_t l);</pre> |
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|
5358 |
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|
5359 <p> |
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|
5360 Adds the string pointed to by <code>s</code> with length <code>l</code> to |
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|
5361 the buffer <code>B</code> |
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|
5362 (see <a href="#luaL_Buffer"><code>luaL_Buffer</code></a>). |
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|
5363 The string can contain embedded zeros. |
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|
5364 |
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|
5365 |
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|
5366 |
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|
5367 |
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|
5368 |
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|
5369 <hr><h3><a name="luaL_addsize"><code>luaL_addsize</code></a></h3><p> |
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5370 <span class="apii">[-?, +?, <em>e</em>]</span> |
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|
5371 <pre>void luaL_addsize (luaL_Buffer *B, size_t n);</pre> |
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5372 |
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|
5373 <p> |
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|
5374 Adds to the buffer <code>B</code> (see <a href="#luaL_Buffer"><code>luaL_Buffer</code></a>) |
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5375 a string of length <code>n</code> previously copied to the |
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|
5376 buffer area (see <a href="#luaL_prepbuffer"><code>luaL_prepbuffer</code></a>). |
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5377 |
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|
5378 |
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|
5379 |
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|
5380 |
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|
5381 |
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5382 <hr><h3><a name="luaL_addstring"><code>luaL_addstring</code></a></h3><p> |
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5383 <span class="apii">[-?, +?, <em>e</em>]</span> |
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5384 <pre>void luaL_addstring (luaL_Buffer *B, const char *s);</pre> |
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5385 |
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5386 <p> |
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5387 Adds the zero-terminated string pointed to by <code>s</code> |
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5388 to the buffer <code>B</code> |
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|
5389 (see <a href="#luaL_Buffer"><code>luaL_Buffer</code></a>). |
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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_addvalue"><code>luaL_addvalue</code></a></h3><p> |
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5396 <span class="apii">[-1, +?, <em>e</em>]</span> |
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5397 <pre>void luaL_addvalue (luaL_Buffer *B);</pre> |
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5398 |
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5399 <p> |
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5400 Adds the value at the top of the stack |
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5401 to the buffer <code>B</code> |
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|
5402 (see <a href="#luaL_Buffer"><code>luaL_Buffer</code></a>). |
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5403 Pops the value. |
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|
5404 |
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5405 |
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5406 <p> |
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5407 This is the only function on string buffers that can (and must) |
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5408 be called with an extra element on the stack, |
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5409 which is the value to be added to the buffer. |
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5410 |
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5411 |
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5412 |
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5413 |
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5414 |
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5415 <hr><h3><a name="luaL_argcheck"><code>luaL_argcheck</code></a></h3><p> |
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5416 <span class="apii">[-0, +0, <em>v</em>]</span> |
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5417 <pre>void luaL_argcheck (lua_State *L, |
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5418 int cond, |
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5419 int arg, |
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5420 const char *extramsg);</pre> |
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5421 |
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5422 <p> |
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5423 Checks whether <code>cond</code> is true. |
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5424 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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5425 |
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5426 |
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5427 |
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5428 |
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5429 |
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5430 <hr><h3><a name="luaL_argerror"><code>luaL_argerror</code></a></h3><p> |
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5431 <span class="apii">[-0, +0, <em>v</em>]</span> |
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5432 <pre>int luaL_argerror (lua_State *L, int arg, const char *extramsg);</pre> |
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5433 |
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5434 <p> |
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5435 Raises an error reporting a problem with argument <code>arg</code> |
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5436 of the C function that called it, |
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5437 using a standard message |
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5438 that includes <code>extramsg</code> as a comment: |
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5439 |
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|
5440 <pre> |
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5441 bad argument #<em>arg</em> to '<em>funcname</em>' (<em>extramsg</em>) |
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5442 </pre><p> |
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5443 This function never returns. |
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|
5444 |
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|
5445 |
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|
5446 |
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|
5447 |
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|
5448 |
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|
5449 <hr><h3><a name="luaL_Buffer"><code>luaL_Buffer</code></a></h3> |
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5450 <pre>typedef struct luaL_Buffer luaL_Buffer;</pre> |
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5451 |
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|
5452 <p> |
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5453 Type for a <em>string buffer</em>. |
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5454 |
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|
5455 |
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5456 <p> |
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5457 A string buffer allows C code to build Lua strings piecemeal. |
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5458 Its pattern of use is as follows: |
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5459 |
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5460 <ul> |
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|
5461 |
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5462 <li>First declare a variable <code>b</code> of type <a href="#luaL_Buffer"><code>luaL_Buffer</code></a>.</li> |
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5463 |
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5464 <li>Then initialize it with a call <code>luaL_buffinit(L, &b)</code>.</li> |
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5465 |
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|
5466 <li> |
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5467 Then add string pieces to the buffer calling any of |
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5468 the <code>luaL_add*</code> functions. |
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5469 </li> |
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|
5470 |
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5471 <li> |
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5472 Finish by calling <code>luaL_pushresult(&b)</code>. |
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5473 This call leaves the final string on the top of the stack. |
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5474 </li> |
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|
5475 |
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5476 </ul> |
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|
5477 |
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5478 <p> |
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5479 If you know beforehand the total size of the resulting string, |
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5480 you can use the buffer like this: |
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|
5481 |
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|
5482 <ul> |
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|
5483 |
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|
5484 <li>First declare a variable <code>b</code> of type <a href="#luaL_Buffer"><code>luaL_Buffer</code></a>.</li> |
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|
5485 |
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5486 <li>Then initialize it and preallocate a space of |
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5487 size <code>sz</code> with a call <code>luaL_buffinitsize(L, &b, sz)</code>.</li> |
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|
5488 |
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|
5489 <li>Then copy the string into that space.</li> |
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|
5490 |
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|
5491 <li> |
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5492 Finish by calling <code>luaL_pushresultsize(&b, sz)</code>, |
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5493 where <code>sz</code> is the total size of the resulting string |
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5494 copied into that space. |
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|
5495 </li> |
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|
5496 |
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|
5497 </ul> |
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|
5498 |
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5499 <p> |
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5500 During its normal operation, |
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5501 a string buffer uses a variable number of stack slots. |
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5502 So, while using a buffer, you cannot assume that you know where |
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5503 the top of the stack is. |
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5504 You can use the stack between successive calls to buffer operations |
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5505 as long as that use is balanced; |
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5506 that is, |
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|
5507 when you call a buffer operation, |
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5508 the stack is at the same level |
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5509 it was immediately after the previous buffer operation. |
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5510 (The only exception to this rule is <a href="#luaL_addvalue"><code>luaL_addvalue</code></a>.) |
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5511 After calling <a href="#luaL_pushresult"><code>luaL_pushresult</code></a> the stack is back to its |
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5512 level when the buffer was initialized, |
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5513 plus the final string on its top. |
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5514 |
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5515 |
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5516 |
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5517 |
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5518 |
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5519 <hr><h3><a name="luaL_buffinit"><code>luaL_buffinit</code></a></h3><p> |
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5520 <span class="apii">[-0, +0, –]</span> |
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5521 <pre>void luaL_buffinit (lua_State *L, luaL_Buffer *B);</pre> |
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5522 |
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5523 <p> |
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5524 Initializes a buffer <code>B</code>. |
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5525 This function does not allocate any space; |
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5526 the buffer must be declared as a variable |
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5527 (see <a href="#luaL_Buffer"><code>luaL_Buffer</code></a>). |
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5528 |
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5529 |
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|
5530 |
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diff
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|
5531 |
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diff
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|
5532 |
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|
5533 <hr><h3><a name="luaL_buffinitsize"><code>luaL_buffinitsize</code></a></h3><p> |
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|
5534 <span class="apii">[-?, +?, <em>e</em>]</span> |
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|
5535 <pre>char *luaL_buffinitsize (lua_State *L, luaL_Buffer *B, size_t sz);</pre> |
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|
5536 |
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|
5537 <p> |
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|
5538 Equivalent to the sequence |
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|
5539 <a href="#luaL_buffinit"><code>luaL_buffinit</code></a>, <a href="#luaL_prepbuffsize"><code>luaL_prepbuffsize</code></a>. |
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|
5540 |
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|
5541 |
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diff
changeset
|
5542 |
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|
5543 |
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|
5544 |
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5545 <hr><h3><a name="luaL_callmeta"><code>luaL_callmeta</code></a></h3><p> |
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|
5546 <span class="apii">[-0, +(0|1), <em>e</em>]</span> |
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5547 <pre>int luaL_callmeta (lua_State *L, int obj, const char *e);</pre> |
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|
5548 |
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|
5549 <p> |
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|
5550 Calls a metamethod. |
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|
5551 |
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|
5552 |
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|
5553 <p> |
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|
5554 If the object at index <code>obj</code> has a metatable and this |
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|
5555 metatable has a field <code>e</code>, |
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|
5556 this function calls this field passing the object as its only argument. |
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5557 In this case this function returns true and pushes onto the |
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5558 stack the value returned by the call. |
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5559 If there is no metatable or no metamethod, |
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5560 this function returns false (without pushing any value on the stack). |
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5561 |
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|
5562 |
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|
5563 |
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|
5564 |
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|
5565 |
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|
5566 <hr><h3><a name="luaL_checkany"><code>luaL_checkany</code></a></h3><p> |
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5567 <span class="apii">[-0, +0, <em>v</em>]</span> |
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|
5568 <pre>void luaL_checkany (lua_State *L, int arg);</pre> |
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|
5569 |
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|
5570 <p> |
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|
5571 Checks whether the function has an argument |
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|
5572 of any type (including <b>nil</b>) at position <code>arg</code>. |
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|
5573 |
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|
5574 |
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|
5575 |
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|
5576 |
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|
5577 |
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|
5578 <hr><h3><a name="luaL_checkinteger"><code>luaL_checkinteger</code></a></h3><p> |
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|
5579 <span class="apii">[-0, +0, <em>v</em>]</span> |
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|
5580 <pre>lua_Integer luaL_checkinteger (lua_State *L, int arg);</pre> |
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|
5581 |
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|
5582 <p> |
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|
5583 Checks whether the function argument <code>arg</code> is an integer |
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|
5584 (or can be converted to an integer) |
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|
5585 and returns this integer cast to a <a href="#lua_Integer"><code>lua_Integer</code></a>. |
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|
5586 |
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|
5587 |
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|
5588 |
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|
5589 |
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diff
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|
5590 |
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|
5591 <hr><h3><a name="luaL_checklstring"><code>luaL_checklstring</code></a></h3><p> |
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5592 <span class="apii">[-0, +0, <em>v</em>]</span> |
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|
5593 <pre>const char *luaL_checklstring (lua_State *L, int arg, size_t *l);</pre> |
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|
5594 |
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|
5595 <p> |
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|
5596 Checks whether the function argument <code>arg</code> is a string |
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|
5597 and returns this string; |
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|
5598 if <code>l</code> is not <code>NULL</code> fills <code>*l</code> |
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|
5599 with the string's length. |
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|
5600 |
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|
5601 |
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|
5602 <p> |
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|
5603 This function uses <a href="#lua_tolstring"><code>lua_tolstring</code></a> to get its result, |
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|
5604 so all conversions and caveats of that function apply here. |
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|
5605 |
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|
5606 |
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|
5607 |
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|
5608 |
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|
5609 |
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|
5610 <hr><h3><a name="luaL_checknumber"><code>luaL_checknumber</code></a></h3><p> |
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|
5611 <span class="apii">[-0, +0, <em>v</em>]</span> |
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|
5612 <pre>lua_Number luaL_checknumber (lua_State *L, int arg);</pre> |
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|
5613 |
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|
5614 <p> |
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|
5615 Checks whether the function argument <code>arg</code> is a number |
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|
5616 and returns this number. |
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|
5617 |
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|
5618 |
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|
5619 |
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|
5620 |
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|
5621 |
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|
5622 <hr><h3><a name="luaL_checkoption"><code>luaL_checkoption</code></a></h3><p> |
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5623 <span class="apii">[-0, +0, <em>v</em>]</span> |
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|
5624 <pre>int luaL_checkoption (lua_State *L, |
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|
5625 int arg, |
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|
5626 const char *def, |
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|
5627 const char *const lst[]);</pre> |
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|
5628 |
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|
5629 <p> |
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|
5630 Checks whether the function argument <code>arg</code> is a string and |
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|
5631 searches for this string in the array <code>lst</code> |
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|
5632 (which must be NULL-terminated). |
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5633 Returns the index in the array where the string was found. |
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5634 Raises an error if the argument is not a string or |
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|
5635 if the string cannot be found. |
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|
5636 |
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|
5637 |
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|
5638 <p> |
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|
5639 If <code>def</code> is not <code>NULL</code>, |
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|
5640 the function uses <code>def</code> as a default value when |
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|
5641 there is no argument <code>arg</code> or when this argument is <b>nil</b>. |
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|
5642 |
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|
5643 |
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|
5644 <p> |
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|
5645 This is a useful function for mapping strings to C enums. |
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|
5646 (The usual convention in Lua libraries is |
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|
5647 to use strings instead of numbers to select options.) |
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|
5648 |
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|
5649 |
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|
5650 |
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|
5651 |
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diff
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|
5652 |
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|
5653 <hr><h3><a name="luaL_checkstack"><code>luaL_checkstack</code></a></h3><p> |
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5654 <span class="apii">[-0, +0, <em>v</em>]</span> |
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|
5655 <pre>void luaL_checkstack (lua_State *L, int sz, const char *msg);</pre> |
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|
5656 |
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|
5657 <p> |
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|
5658 Grows the stack size to <code>top + sz</code> elements, |
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|
5659 raising an error if the stack cannot grow to that size. |
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|
5660 <code>msg</code> is an additional text to go into the error message |
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|
5661 (or <code>NULL</code> for no additional text). |
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|
5662 |
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|
5663 |
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diff
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5664 |
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diff
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|
5665 |
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diff
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|
5666 |
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|
5667 <hr><h3><a name="luaL_checkstring"><code>luaL_checkstring</code></a></h3><p> |
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|
5668 <span class="apii">[-0, +0, <em>v</em>]</span> |
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|
5669 <pre>const char *luaL_checkstring (lua_State *L, int arg);</pre> |
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|
5670 |
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|
5671 <p> |
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5672 Checks whether the function argument <code>arg</code> is a string |
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5673 and returns this string. |
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|
5674 |
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|
5675 |
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|
5676 <p> |
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|
5677 This function uses <a href="#lua_tolstring"><code>lua_tolstring</code></a> to get its result, |
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|
5678 so all conversions and caveats of that function apply here. |
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|
5679 |
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diff
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|
5680 |
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diff
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|
5681 |
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diff
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|
5682 |
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diff
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|
5683 |
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|
5684 <hr><h3><a name="luaL_checktype"><code>luaL_checktype</code></a></h3><p> |
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|
5685 <span class="apii">[-0, +0, <em>v</em>]</span> |
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|
5686 <pre>void luaL_checktype (lua_State *L, int arg, int t);</pre> |
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|
5687 |
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|
5688 <p> |
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diff
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|
5689 Checks whether the function argument <code>arg</code> has type <code>t</code>. |
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parents:
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|
5690 See <a href="#lua_type"><code>lua_type</code></a> for the encoding of types for <code>t</code>. |
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|
5691 |
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diff
changeset
|
5692 |
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diff
changeset
|
5693 |
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diff
changeset
|
5694 |
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diff
changeset
|
5695 |
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|
5696 <hr><h3><a name="luaL_checkudata"><code>luaL_checkudata</code></a></h3><p> |
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|
5697 <span class="apii">[-0, +0, <em>v</em>]</span> |
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|
5698 <pre>void *luaL_checkudata (lua_State *L, int arg, const char *tname);</pre> |
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|
5699 |
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|
5700 <p> |
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diff
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|
5701 Checks whether the function argument <code>arg</code> is a userdata |
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|
5702 of the type <code>tname</code> (see <a href="#luaL_newmetatable"><code>luaL_newmetatable</code></a>) and |
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|
5703 returns the userdata address (see <a href="#lua_touserdata"><code>lua_touserdata</code></a>). |
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|
5704 |
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diff
changeset
|
5705 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
5706 |
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diff
changeset
|
5707 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
5708 |
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|
5709 <hr><h3><a name="luaL_checkversion"><code>luaL_checkversion</code></a></h3><p> |
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|
5710 <span class="apii">[-0, +0, –]</span> |
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|
5711 <pre>void luaL_checkversion (lua_State *L);</pre> |
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|
5712 |
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|
5713 <p> |
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|
5714 Checks whether the core running the call, |
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|
5715 the core that created the Lua state, |
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|
5716 and the code making the call are all using the same version of Lua. |
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|
5717 Also checks whether the core running the call |
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|
5718 and the core that created the Lua state |
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|
5719 are using the same address space. |
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|
5720 |
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diff
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|
5721 |
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diff
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|
5722 |
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diff
changeset
|
5723 |
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diff
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|
5724 |
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|
5725 <hr><h3><a name="luaL_dofile"><code>luaL_dofile</code></a></h3><p> |
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|
5726 <span class="apii">[-0, +?, <em>e</em>]</span> |
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|
5727 <pre>int luaL_dofile (lua_State *L, const char *filename);</pre> |
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|
5728 |
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|
5729 <p> |
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|
5730 Loads and runs the given file. |
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|
5731 It is defined as the following macro: |
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|
5732 |
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|
5733 <pre> |
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|
5734 (luaL_loadfile(L, filename) || lua_pcall(L, 0, LUA_MULTRET, 0)) |
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|
5735 </pre><p> |
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|
5736 It returns false if there are no errors |
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|
5737 or true in case of errors. |
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changeset
|
5738 |
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diff
changeset
|
5739 |
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diff
changeset
|
5740 |
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diff
changeset
|
5741 |
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diff
changeset
|
5742 |
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|
5743 <hr><h3><a name="luaL_dostring"><code>luaL_dostring</code></a></h3><p> |
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|
5744 <span class="apii">[-0, +?, –]</span> |
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|
5745 <pre>int luaL_dostring (lua_State *L, const char *str);</pre> |
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|
5746 |
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|
5747 <p> |
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|
5748 Loads and runs the given string. |
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|
5749 It is defined as the following macro: |
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|
5750 |
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|
5751 <pre> |
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|
5752 (luaL_loadstring(L, str) || lua_pcall(L, 0, LUA_MULTRET, 0)) |
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|
5753 </pre><p> |
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|
5754 It returns false if there are no errors |
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|
5755 or true in case of errors. |
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|
5756 |
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diff
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|
5757 |
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diff
changeset
|
5758 |
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changeset
|
5759 |
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diff
changeset
|
5760 |
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|
5761 <hr><h3><a name="luaL_error"><code>luaL_error</code></a></h3><p> |
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|
5762 <span class="apii">[-0, +0, <em>v</em>]</span> |
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|
5763 <pre>int luaL_error (lua_State *L, const char *fmt, ...);</pre> |
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|
5764 |
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diff
changeset
|
5765 <p> |
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|
5766 Raises an error. |
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|
5767 The error message format is given by <code>fmt</code> |
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|
5768 plus any extra arguments, |
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|
5769 following the same rules of <a href="#lua_pushfstring"><code>lua_pushfstring</code></a>. |
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|
5770 It also adds at the beginning of the message the file name and |
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|
5771 the line number where the error occurred, |
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|
5772 if this information is available. |
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diff
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|
5773 |
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diff
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|
5774 |
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|
5775 <p> |
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5776 This function never returns, |
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|
5777 but it is an idiom to use it in C functions |
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5778 as <code>return luaL_error(<em>args</em>)</code>. |
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5779 |
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diff
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|
5780 |
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diff
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|
5781 |
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diff
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|
5782 |
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|
5783 |
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5784 <hr><h3><a name="luaL_execresult"><code>luaL_execresult</code></a></h3><p> |
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5785 <span class="apii">[-0, +3, <em>e</em>]</span> |
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|
5786 <pre>int luaL_execresult (lua_State *L, int stat);</pre> |
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|
5787 |
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|
5788 <p> |
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|
5789 This function produces the return values for |
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|
5790 process-related functions in the standard library |
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|
5791 (<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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5792 |
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diff
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|
5793 |
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diff
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|
5794 |
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|
5795 |
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diff
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|
5796 |
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|
5797 <hr><h3><a name="luaL_fileresult"><code>luaL_fileresult</code></a></h3><p> |
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|
5798 <span class="apii">[-0, +(1|3), <em>e</em>]</span> |
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|
5799 <pre>int luaL_fileresult (lua_State *L, int stat, const char *fname);</pre> |
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|
5800 |
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|
5801 <p> |
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|
5802 This function produces the return values for |
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|
5803 file-related functions in the standard library |
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|
5804 (<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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|
5805 |
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|
5806 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
5807 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
5808 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
5809 |
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|
5810 <hr><h3><a name="luaL_getmetafield"><code>luaL_getmetafield</code></a></h3><p> |
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5811 <span class="apii">[-0, +(0|1), <em>e</em>]</span> |
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|
5812 <pre>int luaL_getmetafield (lua_State *L, int obj, const char *e);</pre> |
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|
5813 |
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|
5814 <p> |
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|
5815 Pushes onto the stack the field <code>e</code> from the metatable |
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|
5816 of the object at index <code>obj</code> and returns the type of pushed value. |
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|
5817 If the object does not have a metatable, |
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|
5818 or if the metatable does not have this field, |
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|
5819 pushes nothing and returns <code>LUA_TNIL</code>. |
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|
5820 |
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diff
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|
5821 |
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|
5822 |
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|
5823 |
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|
5824 |
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5825 <hr><h3><a name="luaL_getmetatable"><code>luaL_getmetatable</code></a></h3><p> |
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5826 <span class="apii">[-0, +1, –]</span> |
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|
5827 <pre>int luaL_getmetatable (lua_State *L, const char *tname);</pre> |
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|
5828 |
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|
5829 <p> |
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|
5830 Pushes onto the stack the metatable associated with name <code>tname</code> |
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|
5831 in the registry (see <a href="#luaL_newmetatable"><code>luaL_newmetatable</code></a>). |
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|
5832 If there is no metatable associated with <code>tname</code>, |
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|
5833 returns false and pushes <b>nil</b>. |
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|
5834 |
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|
5835 |
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Franklin Schmidt <fschmidt@gmail.com>
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|
5836 |
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Franklin Schmidt <fschmidt@gmail.com>
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|
5837 |
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|
5838 |
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|
5839 <hr><h3><a name="luaL_getsubtable"><code>luaL_getsubtable</code></a></h3><p> |
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5840 <span class="apii">[-0, +1, <em>e</em>]</span> |
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|
5841 <pre>int luaL_getsubtable (lua_State *L, int idx, const char *fname);</pre> |
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|
5842 |
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|
5843 <p> |
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|
5844 Ensures that the value <code>t[fname]</code>, |
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|
5845 where <code>t</code> is the value at index <code>idx</code>, |
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|
5846 is a table, |
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|
5847 and pushes that table onto the stack. |
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|
5848 Returns true if it finds a previous table there |
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|
5849 and false if it creates a new table. |
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|
5850 |
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|
5851 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
5852 |
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|
5853 |
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Franklin Schmidt <fschmidt@gmail.com>
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|
5854 |
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|
5855 <hr><h3><a name="luaL_gsub"><code>luaL_gsub</code></a></h3><p> |
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|
5856 <span class="apii">[-0, +1, <em>e</em>]</span> |
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|
5857 <pre>const char *luaL_gsub (lua_State *L, |
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|
5858 const char *s, |
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|
5859 const char *p, |
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|
5860 const char *r);</pre> |
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|
5861 |
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|
5862 <p> |
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|
5863 Creates a copy of string <code>s</code> by replacing |
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5864 any occurrence of the string <code>p</code> |
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5865 with the string <code>r</code>. |
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5866 Pushes the resulting string on the stack and returns it. |
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|
5867 |
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|
5868 |
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|
5869 |
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|
5870 |
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|
5871 |
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|
5872 <hr><h3><a name="luaL_len"><code>luaL_len</code></a></h3><p> |
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5873 <span class="apii">[-0, +0, <em>e</em>]</span> |
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5874 <pre>lua_Integer luaL_len (lua_State *L, int index);</pre> |
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|
5875 |
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|
5876 <p> |
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5877 Returns the "length" of the value at the given index |
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|
5878 as a number; |
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|
5879 it is equivalent to the '<code>#</code>' operator in Lua (see <a href="#3.4.7">§3.4.7</a>). |
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5880 Raises an error if the result of the operation is not an integer. |
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|
5881 (This case only can happen through metamethods.) |
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5882 |
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|
5883 |
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|
5884 |
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changeset
|
5885 |
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|
5886 |
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|
5887 <hr><h3><a name="luaL_loadbuffer"><code>luaL_loadbuffer</code></a></h3><p> |
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5888 <span class="apii">[-0, +1, –]</span> |
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5889 <pre>int luaL_loadbuffer (lua_State *L, |
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5890 const char *buff, |
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|
5891 size_t sz, |
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|
5892 const char *name);</pre> |
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|
5893 |
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|
5894 <p> |
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|
5895 Equivalent to <a href="#luaL_loadbufferx"><code>luaL_loadbufferx</code></a> with <code>mode</code> equal to <code>NULL</code>. |
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5896 |
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|
5897 |
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|
5898 |
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|
5899 |
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5900 |
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5901 <hr><h3><a name="luaL_loadbufferx"><code>luaL_loadbufferx</code></a></h3><p> |
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5902 <span class="apii">[-0, +1, –]</span> |
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|
5903 <pre>int luaL_loadbufferx (lua_State *L, |
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5904 const char *buff, |
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5905 size_t sz, |
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5906 const char *name, |
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|
5907 const char *mode);</pre> |
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|
5908 |
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|
5909 <p> |
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5910 Loads a buffer as a Lua chunk. |
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5911 This function uses <a href="#lua_load"><code>lua_load</code></a> to load the chunk in the |
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|
5912 buffer pointed to by <code>buff</code> with size <code>sz</code>. |
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5913 |
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|
5914 |
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5915 <p> |
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5916 This function returns the same results as <a href="#lua_load"><code>lua_load</code></a>. |
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5917 <code>name</code> is the chunk name, |
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5918 used for debug information and error messages. |
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5919 The string <code>mode</code> works as in function <a href="#lua_load"><code>lua_load</code></a>. |
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|
5920 |
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|
5921 |
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|
5922 |
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|
5923 |
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|
5924 |
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5925 <hr><h3><a name="luaL_loadfile"><code>luaL_loadfile</code></a></h3><p> |
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5926 <span class="apii">[-0, +1, <em>e</em>]</span> |
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|
5927 <pre>int luaL_loadfile (lua_State *L, const char *filename);</pre> |
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|
5928 |
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|
5929 <p> |
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5930 Equivalent to <a href="#luaL_loadfilex"><code>luaL_loadfilex</code></a> with <code>mode</code> equal to <code>NULL</code>. |
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|
5931 |
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changeset
|
5932 |
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changeset
|
5933 |
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|
5934 |
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|
5935 |
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|
5936 <hr><h3><a name="luaL_loadfilex"><code>luaL_loadfilex</code></a></h3><p> |
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5937 <span class="apii">[-0, +1, <em>e</em>]</span> |
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|
5938 <pre>int luaL_loadfilex (lua_State *L, const char *filename, |
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|
5939 const char *mode);</pre> |
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|
5940 |
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|
5941 <p> |
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|
5942 Loads a file as a Lua chunk. |
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|
5943 This function uses <a href="#lua_load"><code>lua_load</code></a> to load the chunk in the file |
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|
5944 named <code>filename</code>. |
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|
5945 If <code>filename</code> is <code>NULL</code>, |
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|
5946 then it loads from the standard input. |
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|
5947 The first line in the file is ignored if it starts with a <code>#</code>. |
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|
5948 |
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|
5949 |
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|
5950 <p> |
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|
5951 The string <code>mode</code> works as in function <a href="#lua_load"><code>lua_load</code></a>. |
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|
5952 |
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|
5953 |
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|
5954 <p> |
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|
5955 This function returns the same results as <a href="#lua_load"><code>lua_load</code></a>, |
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|
5956 but it has an extra error code <a name="pdf-LUA_ERRFILE"><code>LUA_ERRFILE</code></a> |
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|
5957 if it cannot open/read the file or the file has a wrong mode. |
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|
5958 |
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|
5959 |
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|
5960 <p> |
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|
5961 As <a href="#lua_load"><code>lua_load</code></a>, this function only loads the chunk; |
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|
5962 it does not run it. |
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|
5963 |
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|
5964 |
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|
5965 |
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|
5966 |
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|
5967 |
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|
5968 <hr><h3><a name="luaL_loadstring"><code>luaL_loadstring</code></a></h3><p> |
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5969 <span class="apii">[-0, +1, –]</span> |
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|
5970 <pre>int luaL_loadstring (lua_State *L, const char *s);</pre> |
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|
5971 |
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|
5972 <p> |
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|
5973 Loads a string as a Lua chunk. |
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|
5974 This function uses <a href="#lua_load"><code>lua_load</code></a> to load the chunk in |
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|
5975 the zero-terminated string <code>s</code>. |
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|
5976 |
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|
5977 |
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|
5978 <p> |
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|
5979 This function returns the same results as <a href="#lua_load"><code>lua_load</code></a>. |
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|
5980 |
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|
5981 |
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|
5982 <p> |
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|
5983 Also as <a href="#lua_load"><code>lua_load</code></a>, this function only loads the chunk; |
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|
5984 it does not run it. |
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changeset
|
5985 |
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|
5986 |
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|
5987 |
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|
5988 |
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|
5989 |
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|
5990 <hr><h3><a name="luaL_newlib"><code>luaL_newlib</code></a></h3><p> |
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|
5991 <span class="apii">[-0, +1, <em>e</em>]</span> |
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|
5992 <pre>void luaL_newlib (lua_State *L, const luaL_Reg l[]);</pre> |
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|
5993 |
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|
5994 <p> |
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|
5995 Creates a new table and registers there |
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|
5996 the functions in list <code>l</code>. |
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|
5997 |
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|
5998 |
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|
5999 <p> |
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|
6000 It is implemented as the following macro: |
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|
6001 |
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|
6002 <pre> |
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|
6003 (luaL_newlibtable(L,l), luaL_setfuncs(L,l,0)) |
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|
6004 </pre><p> |
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|
6005 The array <code>l</code> must be the actual array, |
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|
6006 not a pointer to it. |
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|
6007 |
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|
6008 |
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|
6009 |
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|
6010 |
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|
6011 |
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|
6012 <hr><h3><a name="luaL_newlibtable"><code>luaL_newlibtable</code></a></h3><p> |
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|
6013 <span class="apii">[-0, +1, <em>e</em>]</span> |
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|
6014 <pre>void luaL_newlibtable (lua_State *L, const luaL_Reg l[]);</pre> |
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|
6015 |
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|
6016 <p> |
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|
6017 Creates a new table with a size optimized |
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|
6018 to store all entries in the array <code>l</code> |
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|
6019 (but does not actually store them). |
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|
6020 It is intended to be used in conjunction with <a href="#luaL_setfuncs"><code>luaL_setfuncs</code></a> |
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|
6021 (see <a href="#luaL_newlib"><code>luaL_newlib</code></a>). |
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|
6022 |
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diff
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|
6023 |
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|
6024 <p> |
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6025 It is implemented as a macro. |
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|
6026 The array <code>l</code> must be the actual array, |
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6027 not a pointer to it. |
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diff
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|
6028 |
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diff
changeset
|
6029 |
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parents:
diff
changeset
|
6030 |
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parents:
diff
changeset
|
6031 |
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diff
changeset
|
6032 |
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|
6033 <hr><h3><a name="luaL_newmetatable"><code>luaL_newmetatable</code></a></h3><p> |
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|
6034 <span class="apii">[-0, +1, <em>e</em>]</span> |
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|
6035 <pre>int luaL_newmetatable (lua_State *L, const char *tname);</pre> |
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|
6036 |
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|
6037 <p> |
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|
6038 If the registry already has the key <code>tname</code>, |
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|
6039 returns 0. |
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diff
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|
6040 Otherwise, |
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|
6041 creates a new table to be used as a metatable for userdata, |
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|
6042 adds to this new table the pair <code>__name = tname</code>, |
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|
6043 adds to the registry the pair <code>[tname] = new table</code>, |
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|
6044 and returns 1. |
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|
6045 (The entry <code>__name</code> is used by some error-reporting functions.) |
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|
6046 |
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diff
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|
6047 |
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|
6048 <p> |
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|
6049 In both cases pushes onto the stack the final value associated |
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|
6050 with <code>tname</code> in the registry. |
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|
6051 |
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diff
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|
6052 |
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diff
changeset
|
6053 |
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diff
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|
6054 |
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diff
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|
6055 |
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|
6056 <hr><h3><a name="luaL_newstate"><code>luaL_newstate</code></a></h3><p> |
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6057 <span class="apii">[-0, +0, –]</span> |
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|
6058 <pre>lua_State *luaL_newstate (void);</pre> |
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|
6059 |
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|
6060 <p> |
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|
6061 Creates a new Lua state. |
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|
6062 It calls <a href="#lua_newstate"><code>lua_newstate</code></a> with an |
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6063 allocator based on the standard C <code>realloc</code> function |
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|
6064 and then sets a panic function (see <a href="#4.6">§4.6</a>) that prints |
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6065 an error message to the standard error output in case of fatal |
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6066 errors. |
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|
6067 |
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|
6068 |
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|
6069 <p> |
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|
6070 Returns the new state, |
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|
6071 or <code>NULL</code> if there is a memory allocation error. |
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|
6072 |
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diff
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|
6073 |
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diff
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|
6074 |
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diff
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|
6075 |
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diff
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|
6076 |
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|
6077 <hr><h3><a name="luaL_openlibs"><code>luaL_openlibs</code></a></h3><p> |
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6078 <span class="apii">[-0, +0, <em>e</em>]</span> |
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|
6079 <pre>void luaL_openlibs (lua_State *L);</pre> |
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|
6080 |
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|
6081 <p> |
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|
6082 Opens all standard Lua libraries into the given state. |
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|
6083 |
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diff
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|
6084 |
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diff
changeset
|
6085 |
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parents:
diff
changeset
|
6086 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
6087 |
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|
6088 <hr><h3><a name="luaL_optinteger"><code>luaL_optinteger</code></a></h3><p> |
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|
6089 <span class="apii">[-0, +0, <em>v</em>]</span> |
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|
6090 <pre>lua_Integer luaL_optinteger (lua_State *L, |
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|
6091 int arg, |
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|
6092 lua_Integer d);</pre> |
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|
6093 |
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diff
changeset
|
6094 <p> |
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|
6095 If the function argument <code>arg</code> is an integer |
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|
6096 (or convertible to an integer), |
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|
6097 returns this integer. |
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|
6098 If this argument is absent or is <b>nil</b>, |
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|
6099 returns <code>d</code>. |
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|
6100 Otherwise, raises an error. |
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changeset
|
6101 |
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changeset
|
6102 |
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diff
changeset
|
6103 |
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diff
changeset
|
6104 |
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diff
changeset
|
6105 |
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|
6106 <hr><h3><a name="luaL_optlstring"><code>luaL_optlstring</code></a></h3><p> |
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6107 <span class="apii">[-0, +0, <em>v</em>]</span> |
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6108 <pre>const char *luaL_optlstring (lua_State *L, |
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|
6109 int arg, |
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|
6110 const char *d, |
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|
6111 size_t *l);</pre> |
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|
6112 |
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changeset
|
6113 <p> |
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|
6114 If the function argument <code>arg</code> is a string, |
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|
6115 returns this string. |
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|
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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changeset
|
6119 |
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changeset
|
6120 |
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changeset
|
6121 <p> |
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|
6122 If <code>l</code> is not <code>NULL</code>, |
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|
6123 fills the position <code>*l</code> with the result's length. |
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|
6124 |
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changeset
|
6125 |
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changeset
|
6126 |
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diff
changeset
|
6127 |
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diff
changeset
|
6128 |
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|
6129 <hr><h3><a name="luaL_optnumber"><code>luaL_optnumber</code></a></h3><p> |
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|
6130 <span class="apii">[-0, +0, <em>v</em>]</span> |
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|
6131 <pre>lua_Number luaL_optnumber (lua_State *L, int arg, lua_Number d);</pre> |
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changeset
|
6132 |
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diff
changeset
|
6133 <p> |
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changeset
|
6134 If the function argument <code>arg</code> is a number, |
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changeset
|
6135 returns this number. |
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6136 If this argument is absent or is <b>nil</b>, |
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6137 returns <code>d</code>. |
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6138 Otherwise, raises an error. |
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6139 |
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6140 |
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6141 |
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6142 |
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6143 |
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6144 <hr><h3><a name="luaL_optstring"><code>luaL_optstring</code></a></h3><p> |
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6145 <span class="apii">[-0, +0, <em>v</em>]</span> |
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6146 <pre>const char *luaL_optstring (lua_State *L, |
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6147 int arg, |
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6148 const char *d);</pre> |
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6149 |
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6150 <p> |
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6151 If the function argument <code>arg</code> is a string, |
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6152 returns this string. |
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6153 If this argument is absent or is <b>nil</b>, |
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6154 returns <code>d</code>. |
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6155 Otherwise, raises an error. |
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6156 |
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6157 |
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6158 |
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6159 |
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6160 |
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6161 <hr><h3><a name="luaL_prepbuffer"><code>luaL_prepbuffer</code></a></h3><p> |
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6162 <span class="apii">[-?, +?, <em>e</em>]</span> |
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6163 <pre>char *luaL_prepbuffer (luaL_Buffer *B);</pre> |
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6164 |
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6165 <p> |
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6166 Equivalent to <a href="#luaL_prepbuffsize"><code>luaL_prepbuffsize</code></a> |
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6167 with the predefined size <a name="pdf-LUAL_BUFFERSIZE"><code>LUAL_BUFFERSIZE</code></a>. |
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6168 |
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6169 |
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6170 |
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6171 |
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6172 |
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6173 <hr><h3><a name="luaL_prepbuffsize"><code>luaL_prepbuffsize</code></a></h3><p> |
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6174 <span class="apii">[-?, +?, <em>e</em>]</span> |
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6175 <pre>char *luaL_prepbuffsize (luaL_Buffer *B, size_t sz);</pre> |
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6176 |
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6177 <p> |
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6178 Returns an address to a space of size <code>sz</code> |
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6179 where you can copy a string to be added to buffer <code>B</code> |
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6180 (see <a href="#luaL_Buffer"><code>luaL_Buffer</code></a>). |
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6181 After copying the string into this space you must call |
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6182 <a href="#luaL_addsize"><code>luaL_addsize</code></a> with the size of the string to actually add |
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6183 it to the buffer. |
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6184 |
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6185 |
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6186 |
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6187 |
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6188 |
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6189 <hr><h3><a name="luaL_pushresult"><code>luaL_pushresult</code></a></h3><p> |
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6190 <span class="apii">[-?, +1, <em>e</em>]</span> |
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6191 <pre>void luaL_pushresult (luaL_Buffer *B);</pre> |
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6192 |
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6193 <p> |
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6194 Finishes the use of buffer <code>B</code> leaving the final string on |
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6195 the top of the stack. |
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|
6196 |
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|
6197 |
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|
6198 |
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|
6199 |
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|
6200 |
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6201 <hr><h3><a name="luaL_pushresultsize"><code>luaL_pushresultsize</code></a></h3><p> |
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6202 <span class="apii">[-?, +1, <em>e</em>]</span> |
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6203 <pre>void luaL_pushresultsize (luaL_Buffer *B, size_t sz);</pre> |
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6204 |
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6205 <p> |
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6206 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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6207 |
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6208 |
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|
6209 |
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|
6210 |
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|
6211 |
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6212 <hr><h3><a name="luaL_ref"><code>luaL_ref</code></a></h3><p> |
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6213 <span class="apii">[-1, +0, <em>e</em>]</span> |
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6214 <pre>int luaL_ref (lua_State *L, int t);</pre> |
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6215 |
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6216 <p> |
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6217 Creates and returns a <em>reference</em>, |
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6218 in the table at index <code>t</code>, |
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6219 for the object at the top of the stack (and pops the object). |
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6220 |
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6221 |
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6222 <p> |
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6223 A reference is a unique integer key. |
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6224 As long as you do not manually add integer keys into table <code>t</code>, |
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6225 <a href="#luaL_ref"><code>luaL_ref</code></a> ensures the uniqueness of the key it returns. |
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6226 You can retrieve an object referred by reference <code>r</code> |
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6227 by calling <code>lua_rawgeti(L, t, r)</code>. |
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6228 Function <a href="#luaL_unref"><code>luaL_unref</code></a> frees a reference and its associated object. |
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6229 |
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6230 |
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6231 <p> |
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6232 If the object at the top of the stack is <b>nil</b>, |
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6233 <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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6234 The constant <a name="pdf-LUA_NOREF"><code>LUA_NOREF</code></a> is guaranteed to be different |
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6235 from any reference returned by <a href="#luaL_ref"><code>luaL_ref</code></a>. |
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6236 |
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6237 |
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6238 |
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6239 |
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6240 |
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6241 <hr><h3><a name="luaL_Reg"><code>luaL_Reg</code></a></h3> |
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6242 <pre>typedef struct luaL_Reg { |
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6243 const char *name; |
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6244 lua_CFunction func; |
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6245 } luaL_Reg;</pre> |
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6246 |
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6247 <p> |
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6248 Type for arrays of functions to be registered by |
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6249 <a href="#luaL_setfuncs"><code>luaL_setfuncs</code></a>. |
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6250 <code>name</code> is the function name and <code>func</code> is a pointer to |
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6251 the function. |
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6252 Any array of <a href="#luaL_Reg"><code>luaL_Reg</code></a> must end with a sentinel entry |
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6253 in which both <code>name</code> and <code>func</code> are <code>NULL</code>. |
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6254 |
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|
6255 |
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|
6256 |
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|
6257 |
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diff
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|
6258 |
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6259 <hr><h3><a name="luaL_requiref"><code>luaL_requiref</code></a></h3><p> |
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6260 <span class="apii">[-0, +1, <em>e</em>]</span> |
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6261 <pre>void luaL_requiref (lua_State *L, const char *modname, |
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6262 lua_CFunction openf, int glb);</pre> |
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6263 |
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|
6264 <p> |
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6265 If <code>modname</code> is not already present in <a href="#pdf-package.loaded"><code>package.loaded</code></a>, |
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6266 calls function <code>openf</code> with string <code>modname</code> as an argument |
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6267 and sets the call result in <code>package.loaded[modname]</code>, |
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6268 as if that function has been called through <a href="#pdf-require"><code>require</code></a>. |
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6269 |
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|
6270 |
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6271 <p> |
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6272 If <code>glb</code> is true, |
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6273 also stores the module into global <code>modname</code>. |
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6274 |
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|
6275 |
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|
6276 <p> |
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6277 Leaves a copy of the module on the stack. |
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|
6278 |
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|
6279 |
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diff
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|
6280 |
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|
6281 |
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|
6282 |
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6283 <hr><h3><a name="luaL_setfuncs"><code>luaL_setfuncs</code></a></h3><p> |
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6284 <span class="apii">[-nup, +0, <em>e</em>]</span> |
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6285 <pre>void luaL_setfuncs (lua_State *L, const luaL_Reg *l, int nup);</pre> |
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6286 |
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|
6287 <p> |
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6288 Registers all functions in the array <code>l</code> |
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|
6289 (see <a href="#luaL_Reg"><code>luaL_Reg</code></a>) into the table on the top of the stack |
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6290 (below optional upvalues, see next). |
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|
6291 |
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|
6292 |
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|
6293 <p> |
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6294 When <code>nup</code> is not zero, |
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|
6295 all functions are created sharing <code>nup</code> upvalues, |
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|
6296 which must be previously pushed on the stack |
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6297 on top of the library table. |
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6298 These values are popped from the stack after the registration. |
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|
6299 |
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|
6300 |
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diff
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|
6301 |
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|
6302 |
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|
6303 |
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|
6304 <hr><h3><a name="luaL_setmetatable"><code>luaL_setmetatable</code></a></h3><p> |
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6305 <span class="apii">[-0, +0, –]</span> |
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|
6306 <pre>void luaL_setmetatable (lua_State *L, const char *tname);</pre> |
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6307 |
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|
6308 <p> |
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6309 Sets the metatable of the object at the top of the stack |
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6310 as the metatable associated with name <code>tname</code> |
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|
6311 in the registry (see <a href="#luaL_newmetatable"><code>luaL_newmetatable</code></a>). |
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|
6312 |
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|
6313 |
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|
6314 |
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|
6315 |
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|
6316 |
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6317 <hr><h3><a name="luaL_Stream"><code>luaL_Stream</code></a></h3> |
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6318 <pre>typedef struct luaL_Stream { |
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|
6319 FILE *f; |
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6320 lua_CFunction closef; |
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|
6321 } luaL_Stream;</pre> |
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|
6322 |
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|
6323 <p> |
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6324 The standard representation for file handles, |
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|
6325 which is used by the standard I/O library. |
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|
6326 |
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|
6327 |
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|
6328 <p> |
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6329 A file handle is implemented as a full userdata, |
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6330 with a metatable called <code>LUA_FILEHANDLE</code> |
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|
6331 (where <code>LUA_FILEHANDLE</code> is a macro with the actual metatable's name). |
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6332 The metatable is created by the I/O library |
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|
6333 (see <a href="#luaL_newmetatable"><code>luaL_newmetatable</code></a>). |
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|
6334 |
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|
6335 |
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|
6336 <p> |
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|
6337 This userdata must start with the structure <code>luaL_Stream</code>; |
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|
6338 it can contain other data after this initial structure. |
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6339 Field <code>f</code> points to the corresponding C stream |
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6340 (or it can be <code>NULL</code> to indicate an incompletely created handle). |
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6341 Field <code>closef</code> points to a Lua function |
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6342 that will be called to close the stream |
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6343 when the handle is closed or collected; |
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6344 this function receives the file handle as its sole argument and |
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6345 must return either <b>true</b> (in case of success) |
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6346 or <b>nil</b> plus an error message (in case of error). |
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6347 Once Lua calls this field, |
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6348 the field value is changed to <code>NULL</code> |
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6349 to signal that the handle is closed. |
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|
6350 |
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|
6351 |
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|
6352 |
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|
6353 |
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|
6354 |
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6355 <hr><h3><a name="luaL_testudata"><code>luaL_testudata</code></a></h3><p> |
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6356 <span class="apii">[-0, +0, <em>e</em>]</span> |
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6357 <pre>void *luaL_testudata (lua_State *L, int arg, const char *tname);</pre> |
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6358 |
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|
6359 <p> |
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|
6360 This function works like <a href="#luaL_checkudata"><code>luaL_checkudata</code></a>, |
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6361 except that, when the test fails, |
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6362 it returns <code>NULL</code> instead of raising an error. |
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|
6363 |
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|
6364 |
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6365 |
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6366 |
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6367 |
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6368 <hr><h3><a name="luaL_tolstring"><code>luaL_tolstring</code></a></h3><p> |
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6369 <span class="apii">[-0, +1, <em>e</em>]</span> |
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|
6370 <pre>const char *luaL_tolstring (lua_State *L, int idx, size_t *len);</pre> |
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|
6371 |
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|
6372 <p> |
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6373 Converts any Lua value at the given index to a C string |
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6374 in a reasonable format. |
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6375 The resulting string is pushed onto the stack and also |
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6376 returned by the function. |
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6377 If <code>len</code> is not <code>NULL</code>, |
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6378 the function also sets <code>*len</code> with the string length. |
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6379 |
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6380 |
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6381 <p> |
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6382 If the value has a metatable with a <code>"__tostring"</code> field, |
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6383 then <code>luaL_tolstring</code> calls the corresponding metamethod |
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6384 with the value as argument, |
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6385 and uses the result of the call as its result. |
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6386 |
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|
6387 |
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6388 |
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6389 |
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6390 |
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6391 <hr><h3><a name="luaL_traceback"><code>luaL_traceback</code></a></h3><p> |
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6392 <span class="apii">[-0, +1, <em>e</em>]</span> |
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6393 <pre>void luaL_traceback (lua_State *L, lua_State *L1, const char *msg, |
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6394 int level);</pre> |
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|
6395 |
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|
6396 <p> |
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6397 Creates and pushes a traceback of the stack <code>L1</code>. |
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6398 If <code>msg</code> is not <code>NULL</code> it is appended |
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6399 at the beginning of the traceback. |
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6400 The <code>level</code> parameter tells at which level |
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6401 to start the traceback. |
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|
6402 |
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6403 |
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|
6404 |
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|
6405 |
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|
6406 |
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6407 <hr><h3><a name="luaL_typename"><code>luaL_typename</code></a></h3><p> |
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6408 <span class="apii">[-0, +0, –]</span> |
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6409 <pre>const char *luaL_typename (lua_State *L, int index);</pre> |
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|
6410 |
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|
6411 <p> |
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6412 Returns the name of the type of the value at the given index. |
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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_unref"><code>luaL_unref</code></a></h3><p> |
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6419 <span class="apii">[-0, +0, –]</span> |
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6420 <pre>void luaL_unref (lua_State *L, int t, int ref);</pre> |
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6421 |
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|
6422 <p> |
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6423 Releases reference <code>ref</code> from the table at index <code>t</code> |
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6424 (see <a href="#luaL_ref"><code>luaL_ref</code></a>). |
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6425 The entry is removed from the table, |
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|
6426 so that the referred object can be collected. |
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6427 The reference <code>ref</code> is also freed to be used again. |
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|
6428 |
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|
6429 |
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|
6430 <p> |
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|
6431 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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6432 <a href="#luaL_unref"><code>luaL_unref</code></a> does nothing. |
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|
6433 |
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|
6434 |
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|
6435 |
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|
6436 |
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|
6437 |
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|
6438 <hr><h3><a name="luaL_where"><code>luaL_where</code></a></h3><p> |
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6439 <span class="apii">[-0, +1, <em>e</em>]</span> |
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6440 <pre>void luaL_where (lua_State *L, int lvl);</pre> |
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6441 |
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|
6442 <p> |
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6443 Pushes onto the stack a string identifying the current position |
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6444 of the control at level <code>lvl</code> in the call stack. |
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|
6445 Typically this string has the following format: |
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|
6446 |
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|
6447 <pre> |
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6448 <em>chunkname</em>:<em>currentline</em>: |
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6449 </pre><p> |
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6450 Level 0 is the running function, |
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6451 level 1 is the function that called the running function, |
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6452 etc. |
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|
6453 |
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|
6454 |
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|
6455 <p> |
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|
6456 This function is used to build a prefix for error messages. |
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|
6457 |
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|
6458 |
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|
6459 |
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|
6460 |
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|
6461 |
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|
6462 |
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|
6463 |
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|
6464 <h1>6 – <a name="6">Standard Libraries</a></h1> |
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6465 |
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|
6466 <p> |
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6467 The standard Lua libraries provide useful functions |
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6468 that are implemented directly through the C API. |
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6469 Some of these functions provide essential services to the language |
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|
6470 (e.g., <a href="#pdf-type"><code>type</code></a> and <a href="#pdf-getmetatable"><code>getmetatable</code></a>); |
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6471 others provide access to "outside" services (e.g., I/O); |
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6472 and others could be implemented in Lua itself, |
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6473 but are quite useful or have critical performance requirements that |
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6474 deserve an implementation in C (e.g., <a href="#pdf-table.sort"><code>table.sort</code></a>). |
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6475 |
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|
6476 |
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|
6477 <p> |
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6478 All libraries are implemented through the official C API |
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6479 and are provided as separate C modules. |
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6480 Currently, Lua has the following standard libraries: |
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6481 |
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|
6482 <ul> |
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6483 |
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6484 <li>basic library (<a href="#6.1">§6.1</a>);</li> |
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6485 |
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6486 <li>coroutine library (<a href="#6.2">§6.2</a>);</li> |
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6487 |
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6488 <li>package library (<a href="#6.3">§6.3</a>);</li> |
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6489 |
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6490 <li>string manipulation (<a href="#6.4">§6.4</a>);</li> |
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6491 |
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6492 <li>basic UTF-8 support (<a href="#6.5">§6.5</a>);</li> |
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6493 |
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6494 <li>table manipulation (<a href="#6.6">§6.6</a>);</li> |
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6495 |
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6496 <li>mathematical functions (<a href="#6.7">§6.7</a>) (sin, log, etc.);</li> |
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6497 |
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6498 <li>input and output (<a href="#6.8">§6.8</a>);</li> |
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6499 |
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6500 <li>operating system facilities (<a href="#6.9">§6.9</a>);</li> |
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6501 |
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6502 <li>debug facilities (<a href="#6.10">§6.10</a>).</li> |
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6503 |
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6504 </ul><p> |
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6505 Except for the basic and the package libraries, |
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6506 each library provides all its functions as fields of a global table |
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6507 or as methods of its objects. |
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6508 |
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6509 |
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6510 <p> |
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6511 To have access to these libraries, |
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6512 the C host program should call the <a href="#luaL_openlibs"><code>luaL_openlibs</code></a> function, |
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6513 which opens all standard libraries. |
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6514 Alternatively, |
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6515 the host program can open them individually by using |
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6516 <a href="#luaL_requiref"><code>luaL_requiref</code></a> to call |
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6517 <a name="pdf-luaopen_base"><code>luaopen_base</code></a> (for the basic library), |
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6518 <a name="pdf-luaopen_package"><code>luaopen_package</code></a> (for the package library), |
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6519 <a name="pdf-luaopen_coroutine"><code>luaopen_coroutine</code></a> (for the coroutine library), |
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6520 <a name="pdf-luaopen_string"><code>luaopen_string</code></a> (for the string library), |
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6521 <a name="pdf-luaopen_utf8"><code>luaopen_utf8</code></a> (for the UTF8 library), |
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6522 <a name="pdf-luaopen_table"><code>luaopen_table</code></a> (for the table library), |
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6523 <a name="pdf-luaopen_math"><code>luaopen_math</code></a> (for the mathematical library), |
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6524 <a name="pdf-luaopen_io"><code>luaopen_io</code></a> (for the I/O library), |
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6525 <a name="pdf-luaopen_os"><code>luaopen_os</code></a> (for the operating system library), |
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6526 and <a name="pdf-luaopen_debug"><code>luaopen_debug</code></a> (for the debug library). |
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6527 These functions are declared in <a name="pdf-lualib.h"><code>lualib.h</code></a>. |
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6528 |
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6529 |
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6530 |
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6531 <h2>6.1 – <a name="6.1">Basic Functions</a></h2> |
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6532 |
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6533 <p> |
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6534 The basic library provides core functions to Lua. |
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6535 If you do not include this library in your application, |
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6536 you should check carefully whether you need to provide |
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6537 implementations for some of its facilities. |
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6538 |
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6539 |
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6540 <p> |
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6541 <hr><h3><a name="pdf-assert"><code>assert (v [, message])</code></a></h3> |
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6542 |
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|
6543 |
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6544 <p> |
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6545 Calls <a href="#pdf-error"><code>error</code></a> if |
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6546 the value of its argument <code>v</code> is false (i.e., <b>nil</b> or <b>false</b>); |
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6547 otherwise, returns all its arguments. |
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6548 In case of error, |
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6549 <code>message</code> is the error object; |
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6550 when absent, it defaults to "<code>assertion failed!</code>" |
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6551 |
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6552 |
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6553 |
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6554 |
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6555 <p> |
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6556 <hr><h3><a name="pdf-collectgarbage"><code>collectgarbage ([opt [, arg]])</code></a></h3> |
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6557 |
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|
6558 |
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6559 <p> |
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6560 This function is a generic interface to the garbage collector. |
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6561 It performs different functions according to its first argument, <code>opt</code>: |
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6562 |
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6563 <ul> |
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|
6564 |
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6565 <li><b>"<code>collect</code>": </b> |
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6566 performs a full garbage-collection cycle. |
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6567 This is the default option. |
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6568 </li> |
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6569 |
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6570 <li><b>"<code>stop</code>": </b> |
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6571 stops automatic execution of the garbage collector. |
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6572 The collector will run only when explicitly invoked, |
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6573 until a call to restart it. |
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6574 </li> |
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6575 |
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6576 <li><b>"<code>restart</code>": </b> |
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6577 restarts automatic execution of the garbage collector. |
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6578 </li> |
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|
6579 |
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6580 <li><b>"<code>count</code>": </b> |
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6581 returns the total memory in use by Lua in Kbytes. |
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6582 The value has a fractional part, |
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6583 so that it multiplied by 1024 |
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6584 gives the exact number of bytes in use by Lua |
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6585 (except for overflows). |
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6586 </li> |
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6587 |
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6588 <li><b>"<code>step</code>": </b> |
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6589 performs a garbage-collection step. |
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6590 The step "size" is controlled by <code>arg</code>. |
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6591 With a zero value, |
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6592 the collector will perform one basic (indivisible) step. |
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6593 For non-zero values, |
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6594 the collector will perform as if that amount of memory |
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6595 (in KBytes) had been allocated by Lua. |
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6596 Returns <b>true</b> if the step finished a collection cycle. |
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6597 </li> |
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6598 |
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6599 <li><b>"<code>setpause</code>": </b> |
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6600 sets <code>arg</code> as the new value for the <em>pause</em> of |
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6601 the collector (see <a href="#2.5">§2.5</a>). |
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6602 Returns the previous value for <em>pause</em>. |
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6603 </li> |
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6604 |
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6605 <li><b>"<code>setstepmul</code>": </b> |
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6606 sets <code>arg</code> as the new value for the <em>step multiplier</em> of |
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6607 the collector (see <a href="#2.5">§2.5</a>). |
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6608 Returns the previous value for <em>step</em>. |
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6609 </li> |
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6610 |
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6611 <li><b>"<code>isrunning</code>": </b> |
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6612 returns a boolean that tells whether the collector is running |
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6613 (i.e., not stopped). |
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6614 </li> |
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6615 |
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6616 </ul> |
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6617 |
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6618 |
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6619 |
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6620 <p> |
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6621 <hr><h3><a name="pdf-dofile"><code>dofile ([filename])</code></a></h3> |
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6622 Opens the named file and executes its contents as a Lua chunk. |
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6623 When called without arguments, |
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6624 <code>dofile</code> executes the contents of the standard input (<code>stdin</code>). |
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6625 Returns all values returned by the chunk. |
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6626 In case of errors, <code>dofile</code> propagates the error |
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6627 to its caller (that is, <code>dofile</code> does not run in protected mode). |
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6628 |
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|
6629 |
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|
6630 |
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|
6631 |
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6632 <p> |
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6633 <hr><h3><a name="pdf-error"><code>error (message [, level])</code></a></h3> |
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6634 Terminates the last protected function called |
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6635 and returns <code>message</code> as the error object. |
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6636 Function <code>error</code> never returns. |
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6637 |
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6638 |
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6639 <p> |
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6640 Usually, <code>error</code> adds some information about the error position |
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6641 at the beginning of the message, if the message is a string. |
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6642 The <code>level</code> argument specifies how to get the error position. |
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6643 With level 1 (the default), the error position is where the |
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6644 <code>error</code> function was called. |
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6645 Level 2 points the error to where the function |
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6646 that called <code>error</code> was called; and so on. |
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6647 Passing a level 0 avoids the addition of error position information |
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6648 to the message. |
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6649 |
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6650 |
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6651 |
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6652 |
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6653 <p> |
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6654 <hr><h3><a name="pdf-_G"><code>_G</code></a></h3> |
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6655 A global variable (not a function) that |
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6656 holds the global environment (see <a href="#2.2">§2.2</a>). |
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6657 Lua itself does not use this variable; |
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6658 changing its value does not affect any environment, |
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6659 nor vice versa. |
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|
6660 |
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|
6661 |
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|
6662 |
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6663 |
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6664 <p> |
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6665 <hr><h3><a name="pdf-getmetatable"><code>getmetatable (object)</code></a></h3> |
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6666 |
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|
6667 |
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6668 <p> |
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6669 If <code>object</code> does not have a metatable, returns <b>nil</b>. |
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6670 Otherwise, |
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6671 if the object's metatable has a <code>"__metatable"</code> field, |
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6672 returns the associated value. |
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6673 Otherwise, returns the metatable of the given object. |
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|
6674 |
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|
6675 |
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|
6676 |
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|
6677 |
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6678 <p> |
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6679 <hr><h3><a name="pdf-ipairs"><code>ipairs (t)</code></a></h3> |
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|
6680 |
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|
6681 |
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6682 <p> |
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6683 Returns three values (an iterator function, the table <code>t</code>, and 0) |
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6684 so that the construction |
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|
6685 |
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6686 <pre> |
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6687 for i,v in ipairs(t) do <em>body</em> end |
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6688 </pre><p> |
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6689 will iterate over the key–value pairs |
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6690 (<code>1,t[1]</code>), (<code>2,t[2]</code>), ..., |
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6691 up to the first nil value. |
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|
6692 |
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|
6693 |
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|
6694 |
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|
6695 |
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|
6696 <p> |
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6697 <hr><h3><a name="pdf-load"><code>load (chunk [, chunkname [, mode [, env]]])</code></a></h3> |
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|
6698 |
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|
6699 |
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|
6700 <p> |
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|
6701 Loads a chunk. |
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|
6702 |
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|
6703 |
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|
6704 <p> |
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|
6705 If <code>chunk</code> is a string, the chunk is this string. |
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|
6706 If <code>chunk</code> is a function, |
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6707 <code>load</code> calls it repeatedly to get the chunk pieces. |
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6708 Each call to <code>chunk</code> must return a string that concatenates |
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6709 with previous results. |
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6710 A return of an empty string, <b>nil</b>, or no value signals the end of the chunk. |
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|
6711 |
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|
6712 |
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6713 <p> |
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6714 If there are no syntactic errors, |
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6715 returns the compiled chunk as a function; |
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6716 otherwise, returns <b>nil</b> plus the error message. |
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|
6717 |
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|
6718 |
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6719 <p> |
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6720 If the resulting function has upvalues, |
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6721 the first upvalue is set to the value of <code>env</code>, |
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6722 if that parameter is given, |
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6723 or to the value of the global environment. |
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6724 Other upvalues are initialized with <b>nil</b>. |
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6725 (When you load a main chunk, |
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6726 the resulting function will always have exactly one upvalue, |
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6727 the <code>_ENV</code> variable (see <a href="#2.2">§2.2</a>). |
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6728 However, |
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6729 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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6730 the resulting function can have an arbitrary number of upvalues.) |
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6731 All upvalues are fresh, that is, |
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6732 they are not shared with any other function. |
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|
6733 |
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|
6734 |
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6735 <p> |
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6736 <code>chunkname</code> is used as the name of the chunk for error messages |
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6737 and debug information (see <a href="#4.9">§4.9</a>). |
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6738 When absent, |
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|
6739 it defaults to <code>chunk</code>, if <code>chunk</code> is a string, |
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|
6740 or to "<code>=(load)</code>" otherwise. |
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|
6741 |
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|
6742 |
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diff
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|
6743 <p> |
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|
6744 The string <code>mode</code> controls whether the chunk can be text or binary |
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|
6745 (that is, a precompiled chunk). |
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|
6746 It may be the string "<code>b</code>" (only binary chunks), |
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6747 "<code>t</code>" (only text chunks), |
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6748 or "<code>bt</code>" (both binary and text). |
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|
6749 The default is "<code>bt</code>". |
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|
6750 |
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|
6751 |
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|
6752 <p> |
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|
6753 Lua does not check the consistency of binary chunks. |
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|
6754 Maliciously crafted binary chunks can crash |
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|
6755 the interpreter. |
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|
6756 |
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|
6757 |
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|
6758 |
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|
6759 |
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|
6760 <p> |
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|
6761 <hr><h3><a name="pdf-loadfile"><code>loadfile ([filename [, mode [, env]]])</code></a></h3> |
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|
6762 |
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|
6763 |
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|
6764 <p> |
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6765 Similar to <a href="#pdf-load"><code>load</code></a>, |
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6766 but gets the chunk from file <code>filename</code> |
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6767 or from the standard input, |
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6768 if no file name is given. |
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|
6769 |
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|
6770 |
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|
6771 |
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|
6772 |
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6773 <p> |
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6774 <hr><h3><a name="pdf-next"><code>next (table [, index])</code></a></h3> |
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|
6775 |
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|
6776 |
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|
6777 <p> |
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6778 Allows a program to traverse all fields of a table. |
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6779 Its first argument is a table and its second argument |
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6780 is an index in this table. |
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6781 <code>next</code> returns the next index of the table |
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6782 and its associated value. |
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6783 When called with <b>nil</b> as its second argument, |
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6784 <code>next</code> returns an initial index |
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6785 and its associated value. |
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6786 When called with the last index, |
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6787 or with <b>nil</b> in an empty table, |
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6788 <code>next</code> returns <b>nil</b>. |
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6789 If the second argument is absent, then it is interpreted as <b>nil</b>. |
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6790 In particular, |
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6791 you can use <code>next(t)</code> to check whether a table is empty. |
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|
6792 |
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|
6793 |
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|
6794 <p> |
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6795 The order in which the indices are enumerated is not specified, |
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6796 <em>even for numeric indices</em>. |
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6797 (To traverse a table in numeric order, |
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6798 use a numerical <b>for</b>.) |
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|
6799 |
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|
6800 |
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|
6801 <p> |
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6802 The behavior of <code>next</code> is undefined if, |
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6803 during the traversal, |
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6804 you assign any value to a non-existent field in the table. |
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6805 You may however modify existing fields. |
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6806 In particular, you may clear existing fields. |
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|
6807 |
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|
6808 |
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|
6809 |
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|
6810 |
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6811 <p> |
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6812 <hr><h3><a name="pdf-pairs"><code>pairs (t)</code></a></h3> |
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|
6813 |
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|
6814 |
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|
6815 <p> |
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|
6816 If <code>t</code> has a metamethod <code>__pairs</code>, |
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|
6817 calls it with <code>t</code> as argument and returns the first three |
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6818 results from the call. |
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|
6819 |
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|
6820 |
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|
6821 <p> |
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|
6822 Otherwise, |
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6823 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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|
6824 so that the construction |
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|
6825 |
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|
6826 <pre> |
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|
6827 for k,v in pairs(t) do <em>body</em> end |
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|
6828 </pre><p> |
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|
6829 will iterate over all key–value pairs of table <code>t</code>. |
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|
6830 |
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|
6831 |
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|
6832 <p> |
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|
6833 See function <a href="#pdf-next"><code>next</code></a> for the caveats of modifying |
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6834 the table during its traversal. |
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changeset
|
6835 |
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|
6836 |
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|
6837 |
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|
6838 |
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|
6839 <p> |
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|
6840 <hr><h3><a name="pdf-pcall"><code>pcall (f [, arg1, ···])</code></a></h3> |
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|
6841 |
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changeset
|
6842 |
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|
6843 <p> |
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|
6844 Calls function <code>f</code> with |
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|
6845 the given arguments in <em>protected mode</em>. |
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6846 This means that any error inside <code>f</code> is not propagated; |
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|
6847 instead, <code>pcall</code> catches the error |
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|
6848 and returns a status code. |
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changeset
|
6849 Its first result is the status code (a boolean), |
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changeset
|
6850 which is true if the call succeeds without errors. |
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|
6851 In such case, <code>pcall</code> also returns all results from the call, |
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|
6852 after this first result. |
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|
6853 In case of any error, <code>pcall</code> returns <b>false</b> plus the error message. |
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changeset
|
6854 |
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changeset
|
6855 |
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diff
changeset
|
6856 |
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diff
changeset
|
6857 |
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changeset
|
6858 <p> |
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|
6859 <hr><h3><a name="pdf-print"><code>print (···)</code></a></h3> |
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changeset
|
6860 Receives any number of arguments |
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changeset
|
6861 and prints their values to <code>stdout</code>, |
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changeset
|
6862 using the <a href="#pdf-tostring"><code>tostring</code></a> function to convert each argument to a string. |
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changeset
|
6863 <code>print</code> is not intended for formatted output, |
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|
6864 but only as a quick way to show a value, |
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|
6865 for instance for debugging. |
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|
6866 For complete control over the output, |
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|
6867 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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|
6868 |
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diff
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|
6869 |
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diff
changeset
|
6870 |
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diff
changeset
|
6871 |
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diff
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|
6872 <p> |
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|
6873 <hr><h3><a name="pdf-rawequal"><code>rawequal (v1, v2)</code></a></h3> |
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|
6874 Checks whether <code>v1</code> is equal to <code>v2</code>, |
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|
6875 without invoking any metamethod. |
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|
6876 Returns a boolean. |
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|
6877 |
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|
6878 |
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|
6879 |
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|
6880 |
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|
6881 <p> |
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|
6882 <hr><h3><a name="pdf-rawget"><code>rawget (table, index)</code></a></h3> |
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6883 Gets the real value of <code>table[index]</code>, |
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6884 without invoking any metamethod. |
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|
6885 <code>table</code> must be a table; |
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6886 <code>index</code> may be any value. |
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|
6887 |
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|
6888 |
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diff
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|
6889 |
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|
6890 |
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|
6891 <p> |
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|
6892 <hr><h3><a name="pdf-rawlen"><code>rawlen (v)</code></a></h3> |
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6893 Returns the length of the object <code>v</code>, |
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|
6894 which must be a table or a string, |
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|
6895 without invoking any metamethod. |
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|
6896 Returns an integer. |
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|
6897 |
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|
6898 |
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diff
changeset
|
6899 |
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|
6900 |
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|
6901 <p> |
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|
6902 <hr><h3><a name="pdf-rawset"><code>rawset (table, index, value)</code></a></h3> |
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|
6903 Sets the real value of <code>table[index]</code> to <code>value</code>, |
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|
6904 without invoking any metamethod. |
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|
6905 <code>table</code> must be a table, |
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|
6906 <code>index</code> any value different from <b>nil</b> and NaN, |
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6907 and <code>value</code> any Lua value. |
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|
6908 |
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|
6909 |
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changeset
|
6910 <p> |
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|
6911 This function returns <code>table</code>. |
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|
6912 |
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|
6913 |
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|
6914 |
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|
6915 |
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|
6916 <p> |
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6917 <hr><h3><a name="pdf-select"><code>select (index, ···)</code></a></h3> |
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|
6918 |
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|
6919 |
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6920 <p> |
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6921 If <code>index</code> is a number, |
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6922 returns all arguments after argument number <code>index</code>; |
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6923 a negative number indexes from the end (-1 is the last argument). |
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|
6924 Otherwise, <code>index</code> must be the string <code>"#"</code>, |
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6925 and <code>select</code> returns the total number of extra arguments it received. |
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|
6926 |
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|
6927 |
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diff
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|
6928 |
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|
6929 |
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6930 <p> |
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|
6931 <hr><h3><a name="pdf-setmetatable"><code>setmetatable (table, metatable)</code></a></h3> |
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|
6932 |
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diff
changeset
|
6933 |
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|
6934 <p> |
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|
6935 Sets the metatable for the given table. |
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|
6936 (You cannot change the metatable of other types from Lua, only from C.) |
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6937 If <code>metatable</code> is <b>nil</b>, |
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6938 removes the metatable of the given table. |
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|
6939 If the original metatable has a <code>"__metatable"</code> field, |
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|
6940 raises an error. |
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changeset
|
6941 |
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changeset
|
6942 |
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changeset
|
6943 <p> |
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changeset
|
6944 This function returns <code>table</code>. |
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changeset
|
6945 |
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changeset
|
6946 |
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diff
changeset
|
6947 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
6948 |
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changeset
|
6949 <p> |
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|
6950 <hr><h3><a name="pdf-tonumber"><code>tonumber (e [, base])</code></a></h3> |
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|
6951 |
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diff
changeset
|
6952 |
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changeset
|
6953 <p> |
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|
6954 When called with no <code>base</code>, |
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|
6955 <code>tonumber</code> tries to convert its argument to a number. |
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changeset
|
6956 If the argument is already a number or |
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|
6957 a string convertible to a number, |
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changeset
|
6958 then <code>tonumber</code> returns this number; |
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|
6959 otherwise, it returns <b>nil</b>. |
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changeset
|
6960 |
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changeset
|
6961 |
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changeset
|
6962 <p> |
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|
6963 The conversion of strings can result in integers or floats, |
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|
6964 according to the lexical conventions of Lua (see <a href="#3.1">§3.1</a>). |
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|
6965 (The string may have leading and trailing spaces and a sign.) |
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changeset
|
6966 |
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changeset
|
6967 |
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changeset
|
6968 <p> |
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|
6969 When called with <code>base</code>, |
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changeset
|
6970 then <code>e</code> must be a string to be interpreted as |
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changeset
|
6971 an integer numeral in that base. |
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diff
changeset
|
6972 The base may be any integer between 2 and 36, inclusive. |
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changeset
|
6973 In bases above 10, the letter '<code>A</code>' (in either upper or lower case) |
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6974 represents 10, '<code>B</code>' represents 11, and so forth, |
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|
6975 with '<code>Z</code>' representing 35. |
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changeset
|
6976 If the string <code>e</code> is not a valid numeral in the given base, |
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changeset
|
6977 the function returns <b>nil</b>. |
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changeset
|
6978 |
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changeset
|
6979 |
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diff
changeset
|
6980 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
6981 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
6982 <p> |
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changeset
|
6983 <hr><h3><a name="pdf-tostring"><code>tostring (v)</code></a></h3> |
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changeset
|
6984 Receives a value of any type and |
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changeset
|
6985 converts it to a string in a human-readable format. |
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changeset
|
6986 Floats always produce strings with some |
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|
6987 floating-point indication (either a decimal dot or an exponent). |
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|
6988 (For complete control of how numbers are converted, |
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|
6989 use <a href="#pdf-string.format"><code>string.format</code></a>.) |
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|
6990 |
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diff
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|
6991 |
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diff
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|
6992 <p> |
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diff
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|
6993 If the metatable of <code>v</code> has a <code>"__tostring"</code> field, |
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|
6994 then <code>tostring</code> calls the corresponding value |
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parents:
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|
6995 with <code>v</code> as argument, |
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|
6996 and uses the result of the call as its result. |
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|
6997 |
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|
6998 |
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|
6999 |
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Franklin Schmidt <fschmidt@gmail.com>
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|
7000 |
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|
7001 <p> |
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|
7002 <hr><h3><a name="pdf-type"><code>type (v)</code></a></h3> |
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|
7003 Returns the type of its only argument, coded as a string. |
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|
7004 The possible results of this function are |
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|
7005 "<code>nil</code>" (a string, not the value <b>nil</b>), |
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|
7006 "<code>number</code>", |
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|
7007 "<code>string</code>", |
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|
7008 "<code>boolean</code>", |
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|
7009 "<code>table</code>", |
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|
7010 "<code>function</code>", |
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|
7011 "<code>thread</code>", |
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|
7012 and "<code>userdata</code>". |
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|
7013 |
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diff
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|
7014 |
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diff
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|
7015 |
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|
7016 |
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|
7017 <p> |
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|
7018 <hr><h3><a name="pdf-_VERSION"><code>_VERSION</code></a></h3> |
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|
7019 A global variable (not a function) that |
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parents:
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|
7020 holds a string containing the current interpreter version. |
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|
7021 The current value of this variable is "<code>Lua 5.3</code>". |
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|
7022 |
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diff
changeset
|
7023 |
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diff
changeset
|
7024 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
7025 |
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Franklin Schmidt <fschmidt@gmail.com>
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|
7026 <p> |
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|
7027 <hr><h3><a name="pdf-xpcall"><code>xpcall (f, msgh [, arg1, ···])</code></a></h3> |
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|
7028 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7029 |
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parents:
diff
changeset
|
7030 <p> |
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|
7031 This function is similar to <a href="#pdf-pcall"><code>pcall</code></a>, |
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parents:
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|
7032 except that it sets a new message handler <code>msgh</code>. |
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parents:
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|
7033 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7034 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7035 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7036 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7037 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
7038 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
7039 |
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|
7040 <h2>6.2 – <a name="6.2">Coroutine Manipulation</a></h2> |
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|
7041 |
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diff
changeset
|
7042 <p> |
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parents:
diff
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|
7043 The operations related to coroutines comprise a sub-library of |
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parents:
diff
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|
7044 the basic library and come inside the table <a name="pdf-coroutine"><code>coroutine</code></a>. |
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|
7045 See <a href="#2.6">§2.6</a> for a general description of coroutines. |
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|
7046 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
7047 |
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diff
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|
7048 <p> |
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|
7049 <hr><h3><a name="pdf-coroutine.create"><code>coroutine.create (f)</code></a></h3> |
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changeset
|
7050 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7051 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
7052 <p> |
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diff
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|
7053 Creates a new coroutine, with body <code>f</code>. |
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|
7054 <code>f</code> must be a Lua function. |
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parents:
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|
7055 Returns this new coroutine, |
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parents:
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|
7056 an object with type <code>"thread"</code>. |
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parents:
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|
7057 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
7058 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
7059 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7060 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7061 <p> |
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parents:
diff
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|
7062 <hr><h3><a name="pdf-coroutine.isyieldable"><code>coroutine.isyieldable ()</code></a></h3> |
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changeset
|
7063 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7064 |
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parents:
diff
changeset
|
7065 <p> |
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|
7066 Returns true when the running coroutine can yield. |
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parents:
diff
changeset
|
7067 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7068 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7069 <p> |
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parents:
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|
7070 A running coroutine is yieldable if it is not the main thread and |
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parents:
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|
7071 it is not inside a non-yieldable C function. |
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parents:
diff
changeset
|
7072 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7073 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7074 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7075 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7076 <p> |
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parents:
diff
changeset
|
7077 <hr><h3><a name="pdf-coroutine.resume"><code>coroutine.resume (co [, val1, ···])</code></a></h3> |
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parents:
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changeset
|
7078 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7079 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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changeset
|
7080 <p> |
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parents:
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|
7081 Starts or continues the execution of coroutine <code>co</code>. |
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parents:
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changeset
|
7082 The first time you resume a coroutine, |
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diff
changeset
|
7083 it starts running its body. |
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parents:
diff
changeset
|
7084 The values <code>val1</code>, ... are passed |
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parents:
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changeset
|
7085 as the arguments to the body function. |
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parents:
diff
changeset
|
7086 If the coroutine has yielded, |
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parents:
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changeset
|
7087 <code>resume</code> restarts it; |
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parents:
diff
changeset
|
7088 the values <code>val1</code>, ... are passed |
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parents:
diff
changeset
|
7089 as the results from the yield. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
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 <p> |
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parents:
diff
changeset
|
7093 If the coroutine runs without any errors, |
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parents:
diff
changeset
|
7094 <code>resume</code> returns <b>true</b> plus any values passed to <code>yield</code> |
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parents:
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changeset
|
7095 (when the coroutine yields) or any values returned by the body function |
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parents:
diff
changeset
|
7096 (when the coroutine terminates). |
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parents:
diff
changeset
|
7097 If there is any error, |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7098 <code>resume</code> returns <b>false</b> plus the error message. |
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parents:
diff
changeset
|
7099 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7100 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7101 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7102 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7103 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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changeset
|
7104 <hr><h3><a name="pdf-coroutine.running"><code>coroutine.running ()</code></a></h3> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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changeset
|
7105 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7106 |
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Franklin Schmidt <fschmidt@gmail.com>
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changeset
|
7107 <p> |
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parents:
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changeset
|
7108 Returns the running coroutine plus a boolean, |
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parents:
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changeset
|
7109 true when the running coroutine is the main one. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7110 |
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parents:
diff
changeset
|
7111 |
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|
7112 |
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diff
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|
7113 |
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|
7114 <p> |
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|
7115 <hr><h3><a name="pdf-coroutine.status"><code>coroutine.status (co)</code></a></h3> |
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|
7116 |
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|
7117 |
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7118 <p> |
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|
7119 Returns the status of coroutine <code>co</code>, as a string: |
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|
7120 <code>"running"</code>, |
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|
7121 if the coroutine is running (that is, it called <code>status</code>); |
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|
7122 <code>"suspended"</code>, if the coroutine is suspended in a call to <code>yield</code>, |
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7123 or if it has not started running yet; |
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7124 <code>"normal"</code> if the coroutine is active but not running |
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7125 (that is, it has resumed another coroutine); |
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7126 and <code>"dead"</code> if the coroutine has finished its body function, |
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7127 or if it has stopped with an error. |
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|
7128 |
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diff
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|
7129 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
7130 |
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Franklin Schmidt <fschmidt@gmail.com>
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|
7131 |
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7132 <p> |
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|
7133 <hr><h3><a name="pdf-coroutine.wrap"><code>coroutine.wrap (f)</code></a></h3> |
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|
7134 |
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|
7135 |
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|
7136 <p> |
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7137 Creates a new coroutine, with body <code>f</code>. |
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7138 <code>f</code> must be a Lua function. |
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7139 Returns a function that resumes the coroutine each time it is called. |
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7140 Any arguments passed to the function behave as the |
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|
7141 extra arguments to <code>resume</code>. |
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7142 Returns the same values returned by <code>resume</code>, |
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7143 except the first boolean. |
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7144 In case of error, propagates the error. |
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|
7145 |
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diff
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|
7146 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
7147 |
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Franklin Schmidt <fschmidt@gmail.com>
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|
7148 |
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|
7149 <p> |
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|
7150 <hr><h3><a name="pdf-coroutine.yield"><code>coroutine.yield (···)</code></a></h3> |
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|
7151 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
7152 |
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|
7153 <p> |
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|
7154 Suspends the execution of the calling coroutine. |
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|
7155 Any arguments to <code>yield</code> are passed as extra results to <code>resume</code>. |
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|
7156 |
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diff
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|
7157 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
7158 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
7159 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7160 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
7161 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
7162 |
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|
7163 <h2>6.3 – <a name="6.3">Modules</a></h2> |
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|
7164 |
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|
7165 <p> |
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|
7166 The package library provides basic |
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|
7167 facilities for loading modules in Lua. |
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|
7168 It exports one function directly in the global environment: |
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|
7169 <a href="#pdf-require"><code>require</code></a>. |
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|
7170 Everything else is exported in a table <a name="pdf-package"><code>package</code></a>. |
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|
7171 |
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diff
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|
7172 |
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|
7173 <p> |
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|
7174 <hr><h3><a name="pdf-require"><code>require (modname)</code></a></h3> |
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|
7175 |
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|
7176 |
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|
7177 <p> |
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|
7178 Loads the given module. |
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|
7179 The function starts by looking into the <a href="#pdf-package.loaded"><code>package.loaded</code></a> table |
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7180 to determine whether <code>modname</code> is already loaded. |
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7181 If it is, then <code>require</code> returns the value stored |
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|
7182 at <code>package.loaded[modname]</code>. |
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|
7183 Otherwise, it tries to find a <em>loader</em> for the module. |
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|
7184 |
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|
7185 |
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|
7186 <p> |
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|
7187 To find a loader, |
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|
7188 <code>require</code> is guided by the <a href="#pdf-package.searchers"><code>package.searchers</code></a> sequence. |
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|
7189 By changing this sequence, |
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diff
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|
7190 we can change how <code>require</code> looks for a module. |
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|
7191 The following explanation is based on the default configuration |
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|
7192 for <a href="#pdf-package.searchers"><code>package.searchers</code></a>. |
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|
7193 |
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|
7194 |
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|
7195 <p> |
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|
7196 First <code>require</code> queries <code>package.preload[modname]</code>. |
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7197 If it has a value, |
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|
7198 this value (which must be a function) is the loader. |
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|
7199 Otherwise <code>require</code> searches for a Lua loader using the |
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|
7200 path stored in <a href="#pdf-package.path"><code>package.path</code></a>. |
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|
7201 If that also fails, it searches for a C loader using the |
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parents:
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|
7202 path stored in <a href="#pdf-package.cpath"><code>package.cpath</code></a>. |
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|
7203 If that also fails, |
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|
7204 it tries an <em>all-in-one</em> loader (see <a href="#pdf-package.searchers"><code>package.searchers</code></a>). |
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|
7205 |
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|
7206 |
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|
7207 <p> |
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|
7208 Once a loader is found, |
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|
7209 <code>require</code> calls the loader with two arguments: |
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|
7210 <code>modname</code> and an extra value dependent on how it got the loader. |
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|
7211 (If the loader came from a file, |
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|
7212 this extra value is the file name.) |
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|
7213 If the loader returns any non-nil value, |
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|
7214 <code>require</code> assigns the returned value to <code>package.loaded[modname]</code>. |
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|
7215 If the loader does not return a non-nil value and |
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|
7216 has not assigned any value to <code>package.loaded[modname]</code>, |
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|
7217 then <code>require</code> assigns <b>true</b> to this entry. |
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|
7218 In any case, <code>require</code> returns the |
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|
7219 final value of <code>package.loaded[modname]</code>. |
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|
7220 |
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changeset
|
7221 |
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|
7222 <p> |
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|
7223 If there is any error loading or running the module, |
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|
7224 or if it cannot find any loader for the module, |
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|
7225 then <code>require</code> raises an error. |
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changeset
|
7226 |
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changeset
|
7227 |
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|
7228 |
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changeset
|
7229 |
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|
7230 <p> |
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|
7231 <hr><h3><a name="pdf-package.config"><code>package.config</code></a></h3> |
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|
7232 |
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parents:
diff
changeset
|
7233 |
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diff
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|
7234 <p> |
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parents:
diff
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|
7235 A string describing some compile-time configurations for packages. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
7236 This string is a sequence of lines: |
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parents:
diff
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|
7237 |
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diff
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|
7238 <ul> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7239 |
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|
7240 <li>The first line is the directory separator string. |
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parents:
diff
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|
7241 Default is '<code>\</code>' for Windows and '<code>/</code>' for all other systems.</li> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
7242 |
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parents:
diff
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|
7243 <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
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
7244 Default is '<code>;</code>'.</li> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
7245 |
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diff
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|
7246 <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
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|
7247 substitution points in a template. |
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parents:
diff
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|
7248 Default is '<code>?</code>'.</li> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
7249 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
7250 <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:
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|
7251 is replaced by the executable's directory. |
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parents:
diff
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|
7252 Default is '<code>!</code>'.</li> |
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parents:
diff
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|
7253 |
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diff
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|
7254 <li>The fifth line is a mark to ignore all text after it |
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parents:
diff
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|
7255 when building the <code>luaopen_</code> function name. |
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parents:
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|
7256 Default is '<code>-</code>'.</li> |
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parents:
diff
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|
7257 |
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parents:
diff
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|
7258 </ul> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7259 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
7260 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
7261 |
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diff
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|
7262 <p> |
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parents:
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|
7263 <hr><h3><a name="pdf-package.cpath"><code>package.cpath</code></a></h3> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
7264 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
7265 |
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diff
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|
7266 <p> |
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parents:
diff
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|
7267 The path used by <a href="#pdf-require"><code>require</code></a> to search for a C loader. |
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parents:
diff
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|
7268 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
7269 |
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diff
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|
7270 <p> |
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|
7271 Lua initializes the C path <a href="#pdf-package.cpath"><code>package.cpath</code></a> in the same way |
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|
7272 it initializes the Lua path <a href="#pdf-package.path"><code>package.path</code></a>, |
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parents:
diff
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|
7273 using the environment variable <a name="pdf-LUA_CPATH_5_3"><code>LUA_CPATH_5_3</code></a> |
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parents:
diff
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|
7274 or the environment variable <a name="pdf-LUA_CPATH"><code>LUA_CPATH</code></a> |
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parents:
diff
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|
7275 or a default path defined in <code>luaconf.h</code>. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
7276 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7277 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7278 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
7279 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
7280 <p> |
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|
7281 <hr><h3><a name="pdf-package.loaded"><code>package.loaded</code></a></h3> |
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|
7282 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
7283 |
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diff
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|
7284 <p> |
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parents:
diff
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|
7285 A table used by <a href="#pdf-require"><code>require</code></a> to control which |
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|
7286 modules are already loaded. |
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parents:
diff
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|
7287 When you require a module <code>modname</code> and |
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parents:
diff
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|
7288 <code>package.loaded[modname]</code> is not false, |
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parents:
diff
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|
7289 <a href="#pdf-require"><code>require</code></a> simply returns the value stored there. |
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parents:
diff
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|
7290 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
7291 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
7292 <p> |
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|
7293 This variable is only a reference to the real table; |
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parents:
diff
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|
7294 assignments to this variable do not change the |
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parents:
diff
changeset
|
7295 table used by <a href="#pdf-require"><code>require</code></a>. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
7296 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7297 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7298 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
7299 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
7300 <p> |
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diff
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|
7301 <hr><h3><a name="pdf-package.loadlib"><code>package.loadlib (libname, funcname)</code></a></h3> |
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diff
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|
7302 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7303 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
7304 <p> |
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parents:
diff
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|
7305 Dynamically links the host program with the C library <code>libname</code>. |
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parents:
diff
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|
7306 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7307 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
7308 <p> |
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parents:
diff
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|
7309 If <code>funcname</code> is "<code>*</code>", |
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|
7310 then it only links with the library, |
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parents:
diff
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|
7311 making the symbols exported by the library |
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parents:
diff
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|
7312 available to other dynamically linked libraries. |
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parents:
diff
changeset
|
7313 Otherwise, |
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parents:
diff
changeset
|
7314 it looks for a function <code>funcname</code> inside the library |
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parents:
diff
changeset
|
7315 and returns this function as a C function. |
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parents:
diff
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|
7316 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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|
7317 (see <a href="#lua_CFunction"><code>lua_CFunction</code></a>). |
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parents:
diff
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|
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 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
7321 This is a low-level function. |
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parents:
diff
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|
7322 It completely bypasses the package and module system. |
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parents:
diff
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|
7323 Unlike <a href="#pdf-require"><code>require</code></a>, |
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|
7324 it does not perform any path searching and |
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parents:
diff
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|
7325 does not automatically adds extensions. |
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parents:
diff
changeset
|
7326 <code>libname</code> must be the complete file name of the C library, |
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parents:
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|
7327 including if necessary a path and an extension. |
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parents:
diff
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|
7328 <code>funcname</code> must be the exact name exported by the C library |
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parents:
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|
7329 (which may depend on the C compiler and linker used). |
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parents:
diff
changeset
|
7330 |
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diff
changeset
|
7331 |
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diff
changeset
|
7332 <p> |
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parents:
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changeset
|
7333 This function is not supported by Standard C. |
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parents:
diff
changeset
|
7334 As such, it is only available on some platforms |
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parents:
diff
changeset
|
7335 (Windows, Linux, Mac OS X, Solaris, BSD, |
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parents:
diff
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|
7336 plus other Unix systems that support the <code>dlfcn</code> standard). |
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parents:
diff
changeset
|
7337 |
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parents:
diff
changeset
|
7338 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7339 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7340 |
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diff
changeset
|
7341 <p> |
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parents:
diff
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|
7342 <hr><h3><a name="pdf-package.path"><code>package.path</code></a></h3> |
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parents:
diff
changeset
|
7343 |
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parents:
diff
changeset
|
7344 |
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diff
changeset
|
7345 <p> |
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parents:
diff
changeset
|
7346 The path used by <a href="#pdf-require"><code>require</code></a> to search for a Lua loader. |
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parents:
diff
changeset
|
7347 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7348 |
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parents:
diff
changeset
|
7349 <p> |
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parents:
diff
changeset
|
7350 At start-up, Lua initializes this variable with |
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parents:
diff
changeset
|
7351 the value of the environment variable <a name="pdf-LUA_PATH_5_3"><code>LUA_PATH_5_3</code></a> or |
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parents:
diff
changeset
|
7352 the environment variable <a name="pdf-LUA_PATH"><code>LUA_PATH</code></a> or |
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parents:
diff
changeset
|
7353 with a default path defined in <code>luaconf.h</code>, |
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parents:
diff
changeset
|
7354 if those environment variables are not defined. |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7355 Any "<code>;;</code>" in the value of the environment variable |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7356 is replaced by the default path. |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7357 |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7358 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7359 |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7360 |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7361 <p> |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7362 <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
changeset
|
7363 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7364 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7365 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7366 A table to store loaders for specific modules |
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
7367 (see <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
changeset
|
7368 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7369 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7370 <p> |
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parents:
diff
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|
7371 This variable is only a reference to the real table; |
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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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|
7372 assignments to this variable do not change the |
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
7373 table used by <a href="#pdf-require"><code>require</code></a>. |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7374 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7375 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7376 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7377 |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7378 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7379 <hr><h3><a name="pdf-package.searchers"><code>package.searchers</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
|
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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parents:
diff
changeset
|
7383 A table used by <a href="#pdf-require"><code>require</code></a> to control how to load modules. |
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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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|
7384 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7385 |
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parents:
diff
changeset
|
7386 <p> |
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parents:
diff
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|
7387 Each entry in this table is a <em>searcher function</em>. |
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parents:
diff
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|
7388 When looking for a module, |
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parents:
diff
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|
7389 <a href="#pdf-require"><code>require</code></a> calls each of these searchers in ascending order, |
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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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|
7390 with the module name (the argument given to <a href="#pdf-require"><code>require</code></a>) as its |
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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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|
7391 sole parameter. |
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parents:
diff
changeset
|
7392 The function can return another function (the module <em>loader</em>) |
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parents:
diff
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|
7393 plus an extra value that will be passed to that loader, |
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
7394 or a string explaining why it did not find that module |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7395 (or <b>nil</b> if it has nothing to say). |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7396 |
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parents:
diff
changeset
|
7397 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7398 <p> |
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parents:
diff
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|
7399 Lua initializes this table with four searcher functions. |
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parents:
diff
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|
7400 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7401 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7402 <p> |
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parents:
diff
changeset
|
7403 The first searcher simply looks for a loader in the |
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
7404 <a href="#pdf-package.preload"><code>package.preload</code></a> table. |
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parents:
diff
changeset
|
7405 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7406 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7407 <p> |
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parents:
diff
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|
7408 The second searcher looks for a loader as a Lua library, |
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parents:
diff
changeset
|
7409 using the path stored at <a href="#pdf-package.path"><code>package.path</code></a>. |
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parents:
diff
changeset
|
7410 The search is done as described in function <a href="#pdf-package.searchpath"><code>package.searchpath</code></a>. |
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
7411 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7412 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7413 <p> |
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parents:
diff
changeset
|
7414 The third searcher looks for a loader as a C library, |
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
7415 using the path given by the variable <a href="#pdf-package.cpath"><code>package.cpath</code></a>. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7416 Again, |
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
7417 the search is done as described in function <a href="#pdf-package.searchpath"><code>package.searchpath</code></a>. |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7418 For instance, |
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
7419 if the C path is the string |
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parents:
diff
changeset
|
7420 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7421 <pre> |
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parents:
diff
changeset
|
7422 "./?.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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parents:
diff
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|
7423 </pre><p> |
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parents:
diff
changeset
|
7424 the searcher for module <code>foo</code> |
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
7425 will try to open the files <code>./foo.so</code>, <code>./foo.dll</code>, |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7426 and <code>/usr/local/foo/init.so</code>, in that order. |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7427 Once it finds a C library, |
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
7428 this searcher first uses a dynamic link facility to link the |
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
7429 application with the library. |
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
7430 Then it tries to find a C function inside the library to |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7431 be used as the loader. |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7432 The name of this C function is the string "<code>luaopen_</code>" |
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
7433 concatenated with a copy of the module name where each dot |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7434 is replaced by an underscore. |
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parents:
diff
changeset
|
7435 Moreover, if the module name has a hyphen, |
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
7436 its suffix after (and including) the first hyphen is removed. |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7437 For instance, if the module name is <code>a.b.c-v2.1</code>, |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7438 the function name will be <code>luaopen_a_b_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
|
7439 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7440 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7441 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7442 The fourth searcher tries an <em>all-in-one loader</em>. |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7443 It searches the C path for a library for |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
7444 the root name of the given module. |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7445 For instance, when requiring <code>a.b.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
|
7446 it will search for a C library for <code>a</code>. |
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parents:
diff
changeset
|
7447 If found, it looks into it for an open function for |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7448 the submodule; |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7449 in our example, that would be <code>luaopen_a_b_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
|
7450 With this facility, a package can pack several C submodules |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7451 into one single library, |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7452 with each submodule keeping its original open function. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7453 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7454 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7455 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
7456 All searchers except the first one (preload) return as the extra value |
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parents:
diff
changeset
|
7457 the file name where the module was found, |
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parents:
diff
changeset
|
7458 as returned by <a href="#pdf-package.searchpath"><code>package.searchpath</code></a>. |
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parents:
diff
changeset
|
7459 The first searcher returns no extra value. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7460 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7461 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7462 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7463 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7464 <p> |
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parents:
diff
changeset
|
7465 <hr><h3><a name="pdf-package.searchpath"><code>package.searchpath (name, path [, sep [, rep]])</code></a></h3> |
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parents:
diff
changeset
|
7466 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7467 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7468 <p> |
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parents:
diff
changeset
|
7469 Searches for the given <code>name</code> in the given <code>path</code>. |
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parents:
diff
changeset
|
7470 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7471 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7472 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7473 A path is a string containing a sequence of |
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parents:
diff
changeset
|
7474 <em>templates</em> separated by semicolons. |
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parents:
diff
changeset
|
7475 For each template, |
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parents:
diff
changeset
|
7476 the function replaces each interrogation mark (if any) |
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|
7477 in the template with a copy of <code>name</code> |
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|
7478 wherein all occurrences of <code>sep</code> |
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|
7479 (a dot, by default) |
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|
7480 were replaced by <code>rep</code> |
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|
7481 (the system's directory separator, by default), |
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|
7482 and then tries to open the resulting file name. |
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|
7483 |
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|
7484 |
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|
7485 <p> |
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7486 For instance, if the path is the string |
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|
7487 |
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|
7488 <pre> |
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|
7489 "./?.lua;./?.lc;/usr/local/?/init.lua" |
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7490 </pre><p> |
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7491 the search for the name <code>foo.a</code> |
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7492 will try to open the files |
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7493 <code>./foo/a.lua</code>, <code>./foo/a.lc</code>, and |
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7494 <code>/usr/local/foo/a/init.lua</code>, in that order. |
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|
7495 |
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|
7496 |
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|
7497 <p> |
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|
7498 Returns the resulting name of the first file that it can |
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7499 open in read mode (after closing the file), |
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7500 or <b>nil</b> plus an error message if none succeeds. |
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7501 (This error message lists all file names it tried to open.) |
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|
7502 |
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|
7503 |
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|
7504 |
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|
7505 |
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|
7506 |
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|
7507 |
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|
7508 |
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|
7509 <h2>6.4 – <a name="6.4">String Manipulation</a></h2> |
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|
7510 |
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|
7511 <p> |
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|
7512 This library provides generic functions for string manipulation, |
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7513 such as finding and extracting substrings, and pattern matching. |
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7514 When indexing a string in Lua, the first character is at position 1 |
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|
7515 (not at 0, as in C). |
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7516 Indices are allowed to be negative and are interpreted as indexing backwards, |
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7517 from the end of the string. |
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7518 Thus, the last character is at position -1, and so on. |
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|
7519 |
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|
7520 |
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|
7521 <p> |
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|
7522 The string library provides all its functions inside the table |
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|
7523 <a name="pdf-string"><code>string</code></a>. |
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7524 It also sets a metatable for strings |
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|
7525 where the <code>__index</code> field points to the <code>string</code> table. |
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|
7526 Therefore, you can use the string functions in object-oriented style. |
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7527 For instance, <code>string.byte(s,i)</code> |
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7528 can be written as <code>s:byte(i)</code>. |
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|
7529 |
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|
7530 |
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7531 <p> |
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|
7532 The string library assumes one-byte character encodings. |
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|
7533 |
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|
7534 |
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|
7535 <p> |
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|
7536 <hr><h3><a name="pdf-string.byte"><code>string.byte (s [, i [, j]])</code></a></h3> |
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7537 Returns the internal numerical codes of the characters <code>s[i]</code>, |
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7538 <code>s[i+1]</code>, ..., <code>s[j]</code>. |
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7539 The default value for <code>i</code> is 1; |
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7540 the default value for <code>j</code> is <code>i</code>. |
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|
7541 These indices are corrected |
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|
7542 following the same rules of function <a href="#pdf-string.sub"><code>string.sub</code></a>. |
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|
7543 |
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|
7544 |
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|
7545 <p> |
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|
7546 Numerical codes are not necessarily portable across platforms. |
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|
7547 |
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|
7548 |
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|
7549 |
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|
7550 |
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|
7551 <p> |
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|
7552 <hr><h3><a name="pdf-string.char"><code>string.char (···)</code></a></h3> |
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|
7553 Receives zero or more integers. |
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|
7554 Returns a string with length equal to the number of arguments, |
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|
7555 in which each character has the internal numerical code equal |
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|
7556 to its corresponding argument. |
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|
7557 |
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|
7558 |
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|
7559 <p> |
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|
7560 Numerical codes are not necessarily portable across platforms. |
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|
7561 |
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|
7562 |
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|
7563 |
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|
7564 |
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|
7565 <p> |
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|
7566 <hr><h3><a name="pdf-string.dump"><code>string.dump (function [, strip])</code></a></h3> |
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|
7567 |
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|
7568 |
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|
7569 <p> |
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|
7570 Returns a string containing a binary representation |
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|
7571 (a <em>binary chunk</em>) |
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|
7572 of the given function, |
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|
7573 so that a later <a href="#pdf-load"><code>load</code></a> on this string returns |
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7574 a copy of the function (but with new upvalues). |
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|
7575 If <code>strip</code> is a true value, |
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|
7576 the binary representation is created without debug information |
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|
7577 about the function |
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|
7578 (local variable names, lines, etc.). |
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|
7579 |
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|
7580 |
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|
7581 <p> |
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|
7582 Functions with upvalues have only their number of upvalues saved. |
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|
7583 When (re)loaded, |
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|
7584 those upvalues receive fresh instances containing <b>nil</b>. |
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|
7585 (You can use the debug library to serialize |
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7586 and reload the upvalues of a function |
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|
7587 in a way adequate to your needs.) |
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|
7588 |
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|
7589 |
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|
7590 |
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|
7591 |
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|
7592 <p> |
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|
7593 <hr><h3><a name="pdf-string.find"><code>string.find (s, pattern [, init [, plain]])</code></a></h3> |
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|
7594 |
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|
7595 |
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|
7596 <p> |
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|
7597 Looks for the first match of |
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|
7598 <code>pattern</code> (see <a href="#6.4.1">§6.4.1</a>) in the string <code>s</code>. |
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|
7599 If it finds a match, then <code>find</code> returns the indices of <code>s</code> |
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|
7600 where this occurrence starts and ends; |
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7601 otherwise, it returns <b>nil</b>. |
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7602 A third, optional numerical argument <code>init</code> specifies |
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7603 where to start the search; |
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7604 its default value is 1 and can be negative. |
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7605 A value of <b>true</b> as a fourth, optional argument <code>plain</code> |
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7606 turns off the pattern matching facilities, |
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7607 so the function does a plain "find substring" operation, |
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7608 with no characters in <code>pattern</code> being considered magic. |
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7609 Note that if <code>plain</code> is given, then <code>init</code> must be given as well. |
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7610 |
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|
7611 |
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7612 <p> |
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7613 If the pattern has captures, |
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7614 then in a successful match |
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7615 the captured values are also returned, |
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7616 after the two indices. |
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|
7617 |
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|
7618 |
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|
7619 |
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|
7620 |
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|
7621 <p> |
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7622 <hr><h3><a name="pdf-string.format"><code>string.format (formatstring, ···)</code></a></h3> |
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7623 |
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|
7624 |
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|
7625 <p> |
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7626 Returns a formatted version of its variable number of arguments |
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7627 following the description given in its first argument (which must be a string). |
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7628 The format string follows the same rules as the ISO C function <code>sprintf</code>. |
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|
7629 The only differences are that the options/modifiers |
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7630 <code>*</code>, <code>h</code>, <code>L</code>, <code>l</code>, <code>n</code>, |
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|
7631 and <code>p</code> are not supported |
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7632 and that there is an extra option, <code>q</code>. |
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7633 The <code>q</code> option formats a string between double quotes, |
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7634 using escape sequences when necessary to ensure that |
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|
7635 it can safely be read back by the Lua interpreter. |
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|
7636 For instance, the call |
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|
7637 |
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|
7638 <pre> |
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|
7639 string.format('%q', 'a string with "quotes" and \n new line') |
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|
7640 </pre><p> |
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|
7641 may produce the string: |
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|
7642 |
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|
7643 <pre> |
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|
7644 "a string with \"quotes\" and \ |
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|
7645 new line" |
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|
7646 </pre> |
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|
7647 |
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|
7648 <p> |
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|
7649 Options |
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|
7650 <code>A</code> and <code>a</code> (when available), |
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|
7651 <code>E</code>, <code>e</code>, <code>f</code>, |
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|
7652 <code>G</code>, and <code>g</code> all expect a number as argument. |
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|
7653 Options <code>c</code>, <code>d</code>, |
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|
7654 <code>i</code>, <code>o</code>, <code>u</code>, <code>X</code>, and <code>x</code> |
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|
7655 expect an integer. |
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|
7656 Option <code>q</code> expects a string; |
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|
7657 option <code>s</code> expects a string without embedded zeros. |
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|
7658 If the argument to option <code>s</code> is not a string, |
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|
7659 it is converted to one following the same rules of <a href="#pdf-tostring"><code>tostring</code></a>. |
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|
7660 |
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|
7661 |
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|
7662 |
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|
7663 |
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|
7664 <p> |
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|
7665 <hr><h3><a name="pdf-string.gmatch"><code>string.gmatch (s, pattern)</code></a></h3> |
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|
7666 Returns an iterator function that, |
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|
7667 each time it is called, |
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|
7668 returns the next captures from <code>pattern</code> (see <a href="#6.4.1">§6.4.1</a>) |
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|
7669 over the string <code>s</code>. |
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|
7670 If <code>pattern</code> specifies no captures, |
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|
7671 then the whole match is produced in each call. |
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|
7672 |
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|
7673 |
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|
7674 <p> |
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|
7675 As an example, the following loop |
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|
7676 will iterate over all the words from string <code>s</code>, |
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|
7677 printing one per line: |
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|
7678 |
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|
7679 <pre> |
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|
7680 s = "hello world from Lua" |
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|
7681 for w in string.gmatch(s, "%a+") do |
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|
7682 print(w) |
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|
7683 end |
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|
7684 </pre><p> |
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|
7685 The next example collects all pairs <code>key=value</code> from the |
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|
7686 given string into a table: |
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|
7687 |
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|
7688 <pre> |
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|
7689 t = {} |
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|
7690 s = "from=world, to=Lua" |
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|
7691 for k, v in string.gmatch(s, "(%w+)=(%w+)") do |
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|
7692 t[k] = v |
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|
7693 end |
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|
7694 </pre> |
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|
7695 |
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|
7696 <p> |
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7697 For this function, a caret '<code>^</code>' at the start of a pattern does not |
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|
7698 work as an anchor, as this would prevent the iteration. |
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|
7699 |
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|
7700 |
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|
7701 |
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|
7702 |
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|
7703 <p> |
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7704 <hr><h3><a name="pdf-string.gsub"><code>string.gsub (s, pattern, repl [, n])</code></a></h3> |
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7705 Returns a copy of <code>s</code> |
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|
7706 in which all (or the first <code>n</code>, if given) |
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7707 occurrences of the <code>pattern</code> (see <a href="#6.4.1">§6.4.1</a>) have been |
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7708 replaced by a replacement string specified by <code>repl</code>, |
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|
7709 which can be a string, a table, or a function. |
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7710 <code>gsub</code> also returns, as its second value, |
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7711 the total number of matches that occurred. |
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7712 The name <code>gsub</code> comes from <em>Global SUBstitution</em>. |
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7713 |
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|
7714 |
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7715 <p> |
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7716 If <code>repl</code> is a string, then its value is used for replacement. |
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7717 The character <code>%</code> works as an escape character: |
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7718 any sequence in <code>repl</code> of the form <code>%<em>d</em></code>, |
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7719 with <em>d</em> between 1 and 9, |
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7720 stands for the value of the <em>d</em>-th captured substring. |
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changeset
|
7721 The sequence <code>%0</code> stands for the whole match. |
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|
7722 The sequence <code>%%</code> stands for a single <code>%</code>. |
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|
7723 |
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diff
changeset
|
7724 |
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diff
changeset
|
7725 <p> |
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diff
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|
7726 If <code>repl</code> is a table, then the table is queried for every match, |
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diff
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|
7727 using the first capture as the key. |
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parents:
diff
changeset
|
7728 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7729 |
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parents:
diff
changeset
|
7730 <p> |
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parents:
diff
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|
7731 If <code>repl</code> is a function, then this function is called every time a |
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parents:
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|
7732 match occurs, with all captured substrings passed as arguments, |
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diff
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|
7733 in order. |
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parents:
diff
changeset
|
7734 |
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diff
changeset
|
7735 |
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diff
changeset
|
7736 <p> |
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diff
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|
7737 In any case, |
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parents:
diff
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|
7738 if the pattern specifies no captures, |
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parents:
diff
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|
7739 then it behaves as if the whole pattern was inside a capture. |
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parents:
diff
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|
7740 |
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parents:
diff
changeset
|
7741 |
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parents:
diff
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|
7742 <p> |
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parents:
diff
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|
7743 If the value returned by the table query or by the function call |
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parents:
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|
7744 is a string or a number, |
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parents:
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|
7745 then it is used as the replacement string; |
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diff
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|
7746 otherwise, if it is <b>false</b> or <b>nil</b>, |
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parents:
diff
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|
7747 then there is no replacement |
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parents:
diff
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|
7748 (that is, the original match is kept in the string). |
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parents:
diff
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|
7749 |
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diff
changeset
|
7750 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
7751 <p> |
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|
7752 Here are some examples: |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
7753 |
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diff
changeset
|
7754 <pre> |
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diff
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|
7755 x = string.gsub("hello world", "(%w+)", "%1 %1") |
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parents:
diff
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|
7756 --> x="hello hello world world" |
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parents:
diff
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|
7757 |
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parents:
diff
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|
7758 x = string.gsub("hello world", "%w+", "%0 %0", 1) |
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parents:
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changeset
|
7759 --> x="hello hello world" |
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parents:
diff
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|
7760 |
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parents:
diff
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|
7761 x = string.gsub("hello world from Lua", "(%w+)%s*(%w+)", "%2 %1") |
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parents:
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|
7762 --> x="world hello Lua from" |
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parents:
diff
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|
7763 |
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parents:
diff
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|
7764 x = string.gsub("home = $HOME, user = $USER", "%$(%w+)", os.getenv) |
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parents:
diff
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|
7765 --> x="home = /home/roberto, user = roberto" |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
7766 |
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diff
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|
7767 x = string.gsub("4+5 = $return 4+5$", "%$(.-)%$", function (s) |
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|
7768 return load(s)() |
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diff
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|
7769 end) |
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|
7770 --> x="4+5 = 9" |
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diff
changeset
|
7771 |
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parents:
diff
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|
7772 local t = {name="lua", version="5.3"} |
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parents:
diff
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|
7773 x = string.gsub("$name-$version.tar.gz", "%$(%w+)", t) |
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parents:
diff
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|
7774 --> x="lua-5.3.tar.gz" |
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diff
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|
7775 </pre> |
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diff
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|
7776 |
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diff
changeset
|
7777 |
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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.len"><code>string.len (s)</code></a></h3> |
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|
7781 Receives a string and returns its length. |
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|
7782 The empty string <code>""</code> has length 0. |
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|
7783 Embedded zeros are counted, |
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|
7784 so <code>"a\000bc\000"</code> has length 5. |
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changeset
|
7785 |
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diff
changeset
|
7786 |
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diff
changeset
|
7787 |
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diff
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|
7788 |
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diff
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|
7789 <p> |
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|
7790 <hr><h3><a name="pdf-string.lower"><code>string.lower (s)</code></a></h3> |
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|
7791 Receives a string and returns a copy of this string with all |
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|
7792 uppercase letters changed to lowercase. |
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|
7793 All other characters are left unchanged. |
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|
7794 The definition of what an uppercase letter is depends on the current locale. |
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|
7795 |
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diff
changeset
|
7796 |
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diff
changeset
|
7797 |
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diff
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|
7798 |
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diff
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|
7799 <p> |
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|
7800 <hr><h3><a name="pdf-string.match"><code>string.match (s, pattern [, init])</code></a></h3> |
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|
7801 Looks for the first <em>match</em> of |
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|
7802 <code>pattern</code> (see <a href="#6.4.1">§6.4.1</a>) in the string <code>s</code>. |
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|
7803 If it finds one, then <code>match</code> returns |
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|
7804 the captures from the pattern; |
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|
7805 otherwise it returns <b>nil</b>. |
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|
7806 If <code>pattern</code> specifies no captures, |
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|
7807 then the whole match is returned. |
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|
7808 A third, optional numerical argument <code>init</code> specifies |
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|
7809 where to start the search; |
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|
7810 its default value is 1 and can be negative. |
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|
7811 |
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diff
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|
7812 |
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diff
changeset
|
7813 |
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diff
changeset
|
7814 |
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diff
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|
7815 <p> |
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|
7816 <hr><h3><a name="pdf-string.pack"><code>string.pack (fmt, v1, v2, ···)</code></a></h3> |
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|
7817 |
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|
7818 |
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|
7819 <p> |
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|
7820 Returns a binary string containing the values <code>v1</code>, <code>v2</code>, etc. |
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|
7821 packed (that is, serialized in binary form) |
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|
7822 according to the format string <code>fmt</code> (see <a href="#6.4.2">§6.4.2</a>). |
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|
7823 |
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changeset
|
7824 |
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diff
changeset
|
7825 |
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changeset
|
7826 |
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changeset
|
7827 <p> |
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|
7828 <hr><h3><a name="pdf-string.packsize"><code>string.packsize (fmt)</code></a></h3> |
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changeset
|
7829 |
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diff
changeset
|
7830 |
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changeset
|
7831 <p> |
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changeset
|
7832 Returns the size of a string resulting from <a href="#pdf-string.pack"><code>string.pack</code></a> |
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changeset
|
7833 with the given format. |
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parents:
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changeset
|
7834 The format string cannot have the variable-length options |
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changeset
|
7835 '<code>s</code>' or '<code>z</code>' (see <a href="#6.4.2">§6.4.2</a>). |
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changeset
|
7836 |
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diff
changeset
|
7837 |
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parents:
diff
changeset
|
7838 |
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diff
changeset
|
7839 |
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changeset
|
7840 <p> |
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changeset
|
7841 <hr><h3><a name="pdf-string.rep"><code>string.rep (s, n [, sep])</code></a></h3> |
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7842 Returns a string that is the concatenation of <code>n</code> copies of |
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changeset
|
7843 the string <code>s</code> separated by the string <code>sep</code>. |
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7844 The default value for <code>sep</code> is the empty string |
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7845 (that is, no separator). |
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7846 Returns the empty string if <code>n</code> is not positive. |
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7847 |
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7848 |
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7849 |
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7850 |
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7851 <p> |
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7852 <hr><h3><a name="pdf-string.reverse"><code>string.reverse (s)</code></a></h3> |
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7853 Returns a string that is the string <code>s</code> reversed. |
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7854 |
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|
7855 |
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|
7856 |
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|
7857 |
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7858 <p> |
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7859 <hr><h3><a name="pdf-string.sub"><code>string.sub (s, i [, j])</code></a></h3> |
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7860 Returns the substring of <code>s</code> that |
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7861 starts at <code>i</code> and continues until <code>j</code>; |
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7862 <code>i</code> and <code>j</code> can be negative. |
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7863 If <code>j</code> is absent, then it is assumed to be equal to -1 |
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7864 (which is the same as the string length). |
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7865 In particular, |
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7866 the call <code>string.sub(s,1,j)</code> returns a prefix of <code>s</code> |
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7867 with length <code>j</code>, |
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7868 and <code>string.sub(s, -i)</code> returns a suffix of <code>s</code> |
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7869 with length <code>i</code>. |
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7870 |
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7871 |
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7872 <p> |
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7873 If, after the translation of negative indices, |
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7874 <code>i</code> is less than 1, |
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7875 it is corrected to 1. |
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7876 If <code>j</code> is greater than the string length, |
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7877 it is corrected to that length. |
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7878 If, after these corrections, |
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7879 <code>i</code> is greater than <code>j</code>, |
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7880 the function returns the empty string. |
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7881 |
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|
7882 |
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|
7883 |
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|
7884 |
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7885 <p> |
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7886 <hr><h3><a name="pdf-string.unpack"><code>string.unpack (fmt, s [, pos])</code></a></h3> |
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7887 |
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|
7888 |
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7889 <p> |
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7890 Returns the values packed in string <code>s</code> (see <a href="#pdf-string.pack"><code>string.pack</code></a>) |
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7891 according to the format string <code>fmt</code> (see <a href="#6.4.2">§6.4.2</a>). |
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7892 An optional <code>pos</code> marks where |
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7893 to start reading in <code>s</code> (default is 1). |
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7894 After the read values, |
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7895 this function also returns the index of the first unread byte in <code>s</code>. |
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7896 |
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|
7897 |
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|
7898 |
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|
7899 |
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7900 <p> |
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7901 <hr><h3><a name="pdf-string.upper"><code>string.upper (s)</code></a></h3> |
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7902 Receives a string and returns a copy of this string with all |
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7903 lowercase letters changed to uppercase. |
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7904 All other characters are left unchanged. |
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7905 The definition of what a lowercase letter is depends on the current locale. |
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7906 |
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|
7907 |
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|
7908 |
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|
7909 |
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7910 |
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7911 <h3>6.4.1 – <a name="6.4.1">Patterns</a></h3> |
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7912 |
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7913 <p> |
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7914 Patterns in Lua are described by regular strings, |
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7915 which are interpreted as patterns by the pattern-matching functions |
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7916 <a href="#pdf-string.find"><code>string.find</code></a>, |
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7917 <a href="#pdf-string.gmatch"><code>string.gmatch</code></a>, |
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7918 <a href="#pdf-string.gsub"><code>string.gsub</code></a>, |
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7919 and <a href="#pdf-string.match"><code>string.match</code></a>. |
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7920 This section describes the syntax and the meaning |
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7921 (that is, what they match) of these strings. |
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7922 |
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|
7923 |
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|
7924 |
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7925 <h4>Character Class:</h4><p> |
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7926 A <em>character class</em> is used to represent a set of characters. |
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7927 The following combinations are allowed in describing a character class: |
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|
7928 |
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|
7929 <ul> |
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|
7930 |
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7931 <li><b><em>x</em>: </b> |
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7932 (where <em>x</em> is not one of the <em>magic characters</em> |
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7933 <code>^$()%.[]*+-?</code>) |
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7934 represents the character <em>x</em> itself. |
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|
7935 </li> |
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|
7936 |
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7937 <li><b><code>.</code>: </b> (a dot) represents all characters.</li> |
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7938 |
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7939 <li><b><code>%a</code>: </b> represents all letters.</li> |
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|
7940 |
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7941 <li><b><code>%c</code>: </b> represents all control characters.</li> |
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7942 |
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7943 <li><b><code>%d</code>: </b> represents all digits.</li> |
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7944 |
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7945 <li><b><code>%g</code>: </b> represents all printable characters except space.</li> |
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7946 |
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7947 <li><b><code>%l</code>: </b> represents all lowercase letters.</li> |
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7948 |
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7949 <li><b><code>%p</code>: </b> represents all punctuation characters.</li> |
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|
7950 |
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7951 <li><b><code>%s</code>: </b> represents all space characters.</li> |
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|
7952 |
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7953 <li><b><code>%u</code>: </b> represents all uppercase letters.</li> |
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|
7954 |
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7955 <li><b><code>%w</code>: </b> represents all alphanumeric characters.</li> |
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7956 |
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7957 <li><b><code>%x</code>: </b> represents all hexadecimal digits.</li> |
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7958 |
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7959 <li><b><code>%<em>x</em></code>: </b> (where <em>x</em> is any non-alphanumeric character) |
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7960 represents the character <em>x</em>. |
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7961 This is the standard way to escape the magic characters. |
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7962 Any non-alphanumeric character |
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7963 (including all punctuations, even the non-magical) |
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7964 can be preceded by a '<code>%</code>' |
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7965 when used to represent itself in a pattern. |
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7966 </li> |
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|
7967 |
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7968 <li><b><code>[<em>set</em>]</code>: </b> |
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7969 represents the class which is the union of all |
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7970 characters in <em>set</em>. |
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7971 A range of characters can be specified by |
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7972 separating the end characters of the range, |
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7973 in ascending order, with a '<code>-</code>'. |
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7974 All classes <code>%</code><em>x</em> described above can also be used as |
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7975 components in <em>set</em>. |
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7976 All other characters in <em>set</em> represent themselves. |
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7977 For example, <code>[%w_]</code> (or <code>[_%w]</code>) |
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7978 represents all alphanumeric characters plus the underscore, |
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7979 <code>[0-7]</code> represents the octal digits, |
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|
7980 and <code>[0-7%l%-]</code> represents the octal digits plus |
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7981 the lowercase letters plus the '<code>-</code>' character. |
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|
7982 |
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|
7983 |
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|
7984 <p> |
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7985 The interaction between ranges and classes is not defined. |
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7986 Therefore, patterns like <code>[%a-z]</code> or <code>[a-%%]</code> |
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7987 have no meaning. |
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7988 </li> |
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|
7989 |
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7990 <li><b><code>[^<em>set</em>]</code>: </b> |
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7991 represents the complement of <em>set</em>, |
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7992 where <em>set</em> is interpreted as above. |
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7993 </li> |
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|
7994 |
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|
7995 </ul><p> |
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|
7996 For all classes represented by single letters (<code>%a</code>, <code>%c</code>, etc.), |
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7997 the corresponding uppercase letter represents the complement of the class. |
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7998 For instance, <code>%S</code> represents all non-space characters. |
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|
7999 |
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|
8000 |
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|
8001 <p> |
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|
8002 The definitions of letter, space, and other character groups |
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8003 depend on the current locale. |
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|
8004 In particular, the class <code>[a-z]</code> may not be equivalent to <code>%l</code>. |
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|
8005 |
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|
8006 |
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|
8007 |
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|
8008 |
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|
8009 |
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8010 <h4>Pattern Item:</h4><p> |
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8011 A <em>pattern item</em> can be |
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|
8012 |
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|
8013 <ul> |
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|
8014 |
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|
8015 <li> |
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8016 a single character class, |
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|
8017 which matches any single character in the class; |
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8018 </li> |
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|
8019 |
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|
8020 <li> |
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8021 a single character class followed by '<code>*</code>', |
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8022 which matches zero or more repetitions of characters in the class. |
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8023 These repetition items will always match the longest possible sequence; |
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8024 </li> |
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|
8025 |
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|
8026 <li> |
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8027 a single character class followed by '<code>+</code>', |
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8028 which matches one or more repetitions of characters in the class. |
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|
8029 These repetition items will always match the longest possible sequence; |
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8030 </li> |
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|
8031 |
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|
8032 <li> |
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8033 a single character class followed by '<code>-</code>', |
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8034 which also matches zero or more repetitions of characters in the class. |
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8035 Unlike '<code>*</code>', |
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|
8036 these repetition items will always match the shortest possible sequence; |
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|
8037 </li> |
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|
8038 |
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|
8039 <li> |
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8040 a single character class followed by '<code>?</code>', |
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8041 which matches zero or one occurrence of a character in the class. |
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8042 It always matches one occurrence if possible; |
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|
8043 </li> |
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|
8044 |
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|
8045 <li> |
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|
8046 <code>%<em>n</em></code>, for <em>n</em> between 1 and 9; |
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|
8047 such item matches a substring equal to the <em>n</em>-th captured string |
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8048 (see below); |
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|
8049 </li> |
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|
8050 |
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|
8051 <li> |
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|
8052 <code>%b<em>xy</em></code>, where <em>x</em> and <em>y</em> are two distinct characters; |
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|
8053 such item matches strings that start with <em>x</em>, end with <em>y</em>, |
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|
8054 and where the <em>x</em> and <em>y</em> are <em>balanced</em>. |
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8055 This means that, if one reads the string from left to right, |
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|
8056 counting <em>+1</em> for an <em>x</em> and <em>-1</em> for a <em>y</em>, |
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|
8057 the ending <em>y</em> is the first <em>y</em> where the count reaches 0. |
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8058 For instance, the item <code>%b()</code> matches expressions with |
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8059 balanced parentheses. |
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|
8060 </li> |
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|
8061 |
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8062 <li> |
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|
8063 <code>%f[<em>set</em>]</code>, a <em>frontier pattern</em>; |
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8064 such item matches an empty string at any position such that |
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8065 the next character belongs to <em>set</em> |
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8066 and the previous character does not belong to <em>set</em>. |
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8067 The set <em>set</em> is interpreted as previously described. |
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8068 The beginning and the end of the subject are handled as if |
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|
8069 they were the character '<code>\0</code>'. |
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|
8070 </li> |
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|
8071 |
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|
8072 </ul> |
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|
8073 |
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|
8074 |
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|
8075 |
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|
8076 |
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|
8077 <h4>Pattern:</h4><p> |
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8078 A <em>pattern</em> is a sequence of pattern items. |
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|
8079 A caret '<code>^</code>' at the beginning of a pattern anchors the match at the |
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8080 beginning of the subject string. |
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|
8081 A '<code>$</code>' at the end of a pattern anchors the match at the |
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8082 end of the subject string. |
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|
8083 At other positions, |
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|
8084 '<code>^</code>' and '<code>$</code>' have no special meaning and represent themselves. |
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8085 |
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8086 |
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8087 |
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8088 |
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8089 |
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8090 <h4>Captures:</h4><p> |
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8091 A pattern can contain sub-patterns enclosed in parentheses; |
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8092 they describe <em>captures</em>. |
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8093 When a match succeeds, the substrings of the subject string |
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8094 that match captures are stored (<em>captured</em>) for future use. |
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8095 Captures are numbered according to their left parentheses. |
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8096 For instance, in the pattern <code>"(a*(.)%w(%s*))"</code>, |
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8097 the part of the string matching <code>"a*(.)%w(%s*)"</code> is |
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8098 stored as the first capture (and therefore has number 1); |
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8099 the character matching "<code>.</code>" is captured with number 2, |
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8100 and the part matching "<code>%s*</code>" has number 3. |
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8101 |
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8102 |
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8103 <p> |
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8104 As a special case, the empty capture <code>()</code> captures |
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8105 the current string position (a number). |
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8106 For instance, if we apply the pattern <code>"()aa()"</code> on the |
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8107 string <code>"flaaap"</code>, there will be two captures: 3 and 5. |
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8108 |
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8109 |
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8110 |
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8111 |
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8112 |
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8113 |
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8114 |
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8115 <h3>6.4.2 – <a name="6.4.2">Format Strings for Pack and Unpack</a></h3> |
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8116 |
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8117 <p> |
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8118 The first argument to <a href="#pdf-string.pack"><code>string.pack</code></a>, |
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8119 <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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8120 is a format string, |
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8121 which describes the layout of the structure being created or read. |
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8122 |
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8123 |
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8124 <p> |
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8125 A format string is a sequence of conversion options. |
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8126 The conversion options are as follows: |
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8127 |
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8128 <ul> |
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8129 <li><b><code><</code>: </b>sets little endian</li> |
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8130 <li><b><code>></code>: </b>sets big endian</li> |
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8131 <li><b><code>=</code>: </b>sets native endian</li> |
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8132 <li><b><code>![<em>n</em>]</code>: </b>sets maximum alignment to <code>n</code> |
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8133 (default is native alignment)</li> |
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8134 <li><b><code>b</code>: </b>a signed byte (<code>char</code>)</li> |
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8135 <li><b><code>B</code>: </b>an unsigned byte (<code>char</code>)</li> |
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8136 <li><b><code>h</code>: </b>a signed <code>short</code> (native size)</li> |
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8137 <li><b><code>H</code>: </b>an unsigned <code>short</code> (native size)</li> |
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8138 <li><b><code>l</code>: </b>a signed <code>long</code> (native size)</li> |
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8139 <li><b><code>L</code>: </b>an unsigned <code>long</code> (native size)</li> |
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8140 <li><b><code>j</code>: </b>a <code>lua_Integer</code></li> |
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8141 <li><b><code>J</code>: </b>a <code>lua_Unsigned</code></li> |
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8142 <li><b><code>T</code>: </b>a <code>size_t</code> (native size)</li> |
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8143 <li><b><code>i[<em>n</em>]</code>: </b>a signed <code>int</code> with <code>n</code> bytes |
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8144 (default is native size)</li> |
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8145 <li><b><code>I[<em>n</em>]</code>: </b>an unsigned <code>int</code> with <code>n</code> bytes |
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8146 (default is native size)</li> |
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8147 <li><b><code>f</code>: </b>a <code>float</code> (native size)</li> |
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8148 <li><b><code>d</code>: </b>a <code>double</code> (native size)</li> |
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8149 <li><b><code>n</code>: </b>a <code>lua_Number</code></li> |
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8150 <li><b><code>c<em>n</em></code>: </b>a fixed-sized string with <code>n</code> bytes</li> |
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8151 <li><b><code>z</code>: </b>a zero-terminated string</li> |
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8152 <li><b><code>s[<em>n</em>]</code>: </b>a string preceded by its length |
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8153 coded as an unsigned integer with <code>n</code> bytes |
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8154 (default is a <code>size_t</code>)</li> |
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8155 <li><b><code>x</code>: </b>one byte of padding</li> |
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8156 <li><b><code>X<em>op</em></code>: </b>an empty item that aligns |
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8157 according to option <code>op</code> |
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8158 (which is otherwise ignored)</li> |
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8159 <li><b>'<code> </code>': </b>(empty space) ignored</li> |
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8160 </ul><p> |
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8161 (A "<code>[<em>n</em>]</code>" means an optional integral numeral.) |
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8162 Except for padding, spaces, and configurations |
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8163 (options "<code>xX <=>!</code>"), |
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8164 each option corresponds to an argument (in <a href="#pdf-string.pack"><code>string.pack</code></a>) |
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8165 or a result (in <a href="#pdf-string.unpack"><code>string.unpack</code></a>). |
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8166 |
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8167 |
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8168 <p> |
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8169 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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8170 <code>n</code> can be any integer between 1 and 16. |
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8171 All integral options check overflows; |
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8172 <a href="#pdf-string.pack"><code>string.pack</code></a> checks whether the given value fits in the given size; |
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8173 <a href="#pdf-string.unpack"><code>string.unpack</code></a> checks whether the read value fits in a Lua integer. |
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8174 |
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8175 |
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8176 <p> |
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8177 Any format string starts as if prefixed by "<code>!1=</code>", |
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8178 that is, |
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8179 with maximum alignment of 1 (no alignment) |
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8180 and native endianness. |
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8181 |
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8182 |
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8183 <p> |
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8184 Alignment works as follows: |
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8185 For each option, |
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8186 the format gets extra padding until the data starts |
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8187 at an offset that is a multiple of the minimum between the |
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8188 option size and the maximum alignment; |
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8189 this minimum must be a power of 2. |
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8190 Options "<code>c</code>" and "<code>z</code>" are not aligned; |
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8191 option "<code>s</code>" follows the alignment of its starting integer. |
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8192 |
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8193 |
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8194 <p> |
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8195 All padding is filled with zeros by <a href="#pdf-string.pack"><code>string.pack</code></a> |
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8196 (and ignored by <a href="#pdf-string.unpack"><code>string.unpack</code></a>). |
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8197 |
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8198 |
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8199 |
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|
8200 |
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diff
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|
8201 |
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|
8202 |
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diff
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|
8203 |
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8204 <h2>6.5 – <a name="6.5">UTF-8 Support</a></h2> |
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8205 |
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8206 <p> |
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|
8207 This library provides basic support for UTF-8 encoding. |
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8208 It provides all its functions inside the table <a name="pdf-utf8"><code>utf8</code></a>. |
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8209 This library does not provide any support for Unicode other |
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8210 than the handling of the encoding. |
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8211 Any operation that needs the meaning of a character, |
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8212 such as character classification, is outside its scope. |
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8213 |
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8214 |
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8215 <p> |
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8216 Unless stated otherwise, |
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8217 all functions that expect a byte position as a parameter |
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8218 assume that the given position is either the start of a byte sequence |
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8219 or one plus the length of the subject string. |
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8220 As in the string library, |
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8221 negative indices count from the end of the string. |
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8222 |
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8223 |
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8224 <p> |
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8225 <hr><h3><a name="pdf-utf8.char"><code>utf8.char (···)</code></a></h3> |
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8226 Receives zero or more integers, |
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8227 converts each one to its corresponding UTF-8 byte sequence |
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8228 and returns a string with the concatenation of all these sequences. |
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8229 |
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8230 |
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|
8231 |
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|
8232 |
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8233 <p> |
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8234 <hr><h3><a name="pdf-utf8.charpattern"><code>utf8.charpattern</code></a></h3> |
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8235 The pattern (a string, not a function) "<code>[\0-\x7F\xC2-\xF4][\x80-\xBF]*</code>" |
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8236 (see <a href="#6.4.1">§6.4.1</a>), |
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8237 which matches exactly one UTF-8 byte sequence, |
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8238 assuming that the subject is a valid UTF-8 string. |
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|
8239 |
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|
8240 |
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|
8241 |
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|
8242 |
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8243 <p> |
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8244 <hr><h3><a name="pdf-utf8.codes"><code>utf8.codes (s)</code></a></h3> |
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|
8245 |
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|
8246 |
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|
8247 <p> |
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|
8248 Returns values so that the construction |
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|
8249 |
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|
8250 <pre> |
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|
8251 for p, c in utf8.codes(s) do <em>body</em> end |
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8252 </pre><p> |
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8253 will iterate over all characters in string <code>s</code>, |
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8254 with <code>p</code> being the position (in bytes) and <code>c</code> the code point |
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8255 of each character. |
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8256 It raises an error if it meets any invalid byte sequence. |
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|
8257 |
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|
8258 |
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|
8259 |
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|
8260 |
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8261 <p> |
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|
8262 <hr><h3><a name="pdf-utf8.codepoint"><code>utf8.codepoint (s [, i [, j]])</code></a></h3> |
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8263 Returns the codepoints (as integers) from all characters in <code>s</code> |
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8264 that start between byte position <code>i</code> and <code>j</code> (both included). |
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8265 The default for <code>i</code> is 1 and for <code>j</code> is <code>i</code>. |
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8266 It raises an error if it meets any invalid byte sequence. |
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|
8267 |
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|
8268 |
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|
8269 |
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|
8270 |
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8271 <p> |
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|
8272 <hr><h3><a name="pdf-utf8.len"><code>utf8.len (s [, i [, j]])</code></a></h3> |
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8273 Returns the number of UTF-8 characters in string <code>s</code> |
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|
8274 that start between positions <code>i</code> and <code>j</code> (both inclusive). |
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8275 The default for <code>i</code> is 1 and for <code>j</code> is -1. |
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8276 If it finds any invalid byte sequence, |
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|
8277 returns a false value plus the position of the first invalid byte. |
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|
8278 |
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|
8279 |
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|
8280 |
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|
8281 |
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|
8282 <p> |
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|
8283 <hr><h3><a name="pdf-utf8.offset"><code>utf8.offset (s, n [, i])</code></a></h3> |
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8284 Returns the position (in bytes) where the encoding of the |
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|
8285 <code>n</code>-th character of <code>s</code> |
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|
8286 (counting from position <code>i</code>) starts. |
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8287 A negative <code>n</code> gets characters before position <code>i</code>. |
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8288 The default for <code>i</code> is 1 when <code>n</code> is non-negative |
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8289 and <code>#s + 1</code> otherwise, |
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8290 so that <code>utf8.offset(s, -n)</code> gets the offset of the |
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8291 <code>n</code>-th character from the end of the string. |
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8292 If the specified character is neither in the subject |
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|
8293 nor right after its end, |
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8294 the function returns <b>nil</b>. |
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|
8295 |
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|
8296 |
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8297 <p> |
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8298 As a special case, |
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8299 when <code>n</code> is 0 the function returns the start of the encoding |
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8300 of the character that contains the <code>i</code>-th byte of <code>s</code>. |
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|
8301 |
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|
8302 |
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|
8303 <p> |
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8304 This function assumes that <code>s</code> is a valid UTF-8 string. |
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|
8305 |
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|
8306 |
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|
8307 |
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|
8308 |
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|
8309 |
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|
8310 |
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8311 |
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8312 <h2>6.6 – <a name="6.6">Table Manipulation</a></h2> |
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8313 |
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|
8314 <p> |
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|
8315 This library provides generic functions for table manipulation. |
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|
8316 It provides all its functions inside the table <a name="pdf-table"><code>table</code></a>. |
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|
8317 |
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|
8318 |
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|
8319 <p> |
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|
8320 Remember that, whenever an operation needs the length of a table, |
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|
8321 the table must be a proper sequence |
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|
8322 or have a <code>__len</code> metamethod (see <a href="#3.4.7">§3.4.7</a>). |
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|
8323 All functions ignore non-numeric keys |
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|
8324 in the tables given as arguments. |
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|
8325 |
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|
8326 |
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|
8327 <p> |
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|
8328 <hr><h3><a name="pdf-table.concat"><code>table.concat (list [, sep [, i [, j]]])</code></a></h3> |
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|
8329 |
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|
8330 |
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|
8331 <p> |
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|
8332 Given a list where all elements are strings or numbers, |
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|
8333 returns the string <code>list[i]..sep..list[i+1] ··· sep..list[j]</code>. |
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|
8334 The default value for <code>sep</code> is the empty string, |
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|
8335 the default for <code>i</code> is 1, |
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|
8336 and the default for <code>j</code> is <code>#list</code>. |
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|
8337 If <code>i</code> is greater than <code>j</code>, returns the empty string. |
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|
8338 |
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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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Franklin Schmidt <fschmidt@gmail.com>
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|
8341 |
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|
8342 <p> |
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|
8343 <hr><h3><a name="pdf-table.insert"><code>table.insert (list, [pos,] value)</code></a></h3> |
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|
8344 |
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|
8345 |
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|
8346 <p> |
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|
8347 Inserts element <code>value</code> at position <code>pos</code> in <code>list</code>, |
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|
8348 shifting up the elements |
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|
8349 <code>list[pos], list[pos+1], ···, list[#list]</code>. |
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|
8350 The default value for <code>pos</code> is <code>#list+1</code>, |
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|
8351 so that a call <code>table.insert(t,x)</code> inserts <code>x</code> at the end |
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|
8352 of list <code>t</code>. |
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|
8353 |
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diff
changeset
|
8354 |
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diff
changeset
|
8355 |
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|
8356 |
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changeset
|
8357 <p> |
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|
8358 <hr><h3><a name="pdf-table.move"><code>table.move (a1, f, e, t [,a2])</code></a></h3> |
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|
8359 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
8360 |
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|
8361 <p> |
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|
8362 Moves elements from table <code>a1</code> to table <code>a2</code>. |
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|
8363 This function performs the equivalent to the following |
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|
8364 multiple assignment: |
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diff
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|
8365 <code>a2[t],··· = a1[f],···,a1[e]</code>. |
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|
8366 The default for <code>a2</code> is <code>a1</code>. |
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|
8367 The destination range can overlap with the source range. |
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|
8368 Index <code>f</code> must be positive. |
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|
8369 |
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diff
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|
8370 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
8371 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
8372 |
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|
8373 <p> |
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|
8374 <hr><h3><a name="pdf-table.pack"><code>table.pack (···)</code></a></h3> |
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|
8375 |
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Franklin Schmidt <fschmidt@gmail.com>
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|
8376 |
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|
8377 <p> |
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|
8378 Returns a new table with all parameters stored into keys 1, 2, etc. |
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8379 and with a field "<code>n</code>" with the total number of parameters. |
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|
8380 Note that the resulting table may not be a sequence. |
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|
8381 |
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diff
changeset
|
8382 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
8383 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
8384 |
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|
8385 <p> |
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|
8386 <hr><h3><a name="pdf-table.remove"><code>table.remove (list [, pos])</code></a></h3> |
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|
8387 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
8388 |
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|
8389 <p> |
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|
8390 Removes from <code>list</code> the element at position <code>pos</code>, |
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|
8391 returning the value of the removed element. |
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diff
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|
8392 When <code>pos</code> is an integer between 1 and <code>#list</code>, |
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|
8393 it shifts down the elements |
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|
8394 <code>list[pos+1], list[pos+2], ···, list[#list]</code> |
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|
8395 and erases element <code>list[#list]</code>; |
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|
8396 The index <code>pos</code> can also be 0 when <code>#list</code> is 0, |
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changeset
|
8397 or <code>#list + 1</code>; |
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diff
changeset
|
8398 in those cases, the function erases the element <code>list[pos]</code>. |
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changeset
|
8399 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
8400 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
8401 <p> |
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|
8402 The default value for <code>pos</code> is <code>#list</code>, |
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|
8403 so that a call <code>table.remove(l)</code> removes the last element |
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changeset
|
8404 of list <code>l</code>. |
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changeset
|
8405 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8406 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8407 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8408 |
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diff
changeset
|
8409 <p> |
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|
8410 <hr><h3><a name="pdf-table.sort"><code>table.sort (list [, comp])</code></a></h3> |
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changeset
|
8411 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
8412 |
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changeset
|
8413 <p> |
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|
8414 Sorts list elements in a given order, <em>in-place</em>, |
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|
8415 from <code>list[1]</code> to <code>list[#list]</code>. |
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|
8416 If <code>comp</code> is given, |
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changeset
|
8417 then it must be a function that receives two list elements |
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|
8418 and returns true when the first element must come |
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|
8419 before the second in the final order |
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changeset
|
8420 (so that <code>not comp(list[i+1],list[i])</code> will be true after the sort). |
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changeset
|
8421 If <code>comp</code> is not given, |
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changeset
|
8422 then the standard Lua operator <code><</code> is used instead. |
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|
8423 |
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diff
changeset
|
8424 |
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changeset
|
8425 <p> |
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changeset
|
8426 The sort algorithm is not stable; |
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changeset
|
8427 that is, elements considered equal by the given order |
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changeset
|
8428 may have their relative positions changed by the sort. |
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diff
changeset
|
8429 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8430 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8431 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
8432 |
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Franklin Schmidt <fschmidt@gmail.com>
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changeset
|
8433 <p> |
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changeset
|
8434 <hr><h3><a name="pdf-table.unpack"><code>table.unpack (list [, i [, j]])</code></a></h3> |
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changeset
|
8435 |
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diff
changeset
|
8436 |
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changeset
|
8437 <p> |
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|
8438 Returns the elements from the given list. |
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changeset
|
8439 This function is equivalent to |
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diff
changeset
|
8440 |
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diff
changeset
|
8441 <pre> |
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diff
changeset
|
8442 return list[i], list[i+1], ···, list[j] |
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|
8443 </pre><p> |
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|
8444 By default, <code>i</code> is 1 and <code>j</code> is <code>#list</code>. |
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|
8445 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
8446 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8447 |
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Franklin Schmidt <fschmidt@gmail.com>
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|
8448 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
8449 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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|
8450 |
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Franklin Schmidt <fschmidt@gmail.com>
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|
8451 |
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|
8452 <h2>6.7 – <a name="6.7">Mathematical Functions</a></h2> |
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|
8453 |
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|
8454 <p> |
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|
8455 This library provides basic mathematical functions. |
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|
8456 It provides all its functions and constants inside the table <a name="pdf-math"><code>math</code></a>. |
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parents:
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|
8457 Functions with the annotation "<code>integer/float</code>" give |
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|
8458 integer results for integer arguments |
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|
8459 and float results for float (or mixed) arguments. |
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|
8460 Rounding functions |
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|
8461 (<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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|
8462 return an integer when the result fits in the range of an integer, |
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8463 or a float otherwise. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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|
8464 |
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Franklin Schmidt <fschmidt@gmail.com>
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|
8465 |
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|
8466 <p> |
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|
8467 <hr><h3><a name="pdf-math.abs"><code>math.abs (x)</code></a></h3> |
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|
8468 |
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|
8469 |
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|
8470 <p> |
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|
8471 Returns the absolute value of <code>x</code>. (integer/float) |
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|
8472 |
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|
8473 |
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|
8474 |
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|
8475 |
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|
8476 <p> |
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|
8477 <hr><h3><a name="pdf-math.acos"><code>math.acos (x)</code></a></h3> |
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|
8478 |
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|
8479 |
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Franklin Schmidt <fschmidt@gmail.com>
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|
8480 <p> |
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|
8481 Returns the arc cosine of <code>x</code> (in radians). |
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parents:
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|
8482 |
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parents:
diff
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|
8483 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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changeset
|
8484 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8485 |
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Franklin Schmidt <fschmidt@gmail.com>
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|
8486 <p> |
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|
8487 <hr><h3><a name="pdf-math.asin"><code>math.asin (x)</code></a></h3> |
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Franklin Schmidt <fschmidt@gmail.com>
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|
8488 |
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Franklin Schmidt <fschmidt@gmail.com>
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changeset
|
8489 |
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Franklin Schmidt <fschmidt@gmail.com>
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|
8490 <p> |
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|
8491 Returns the arc sine of <code>x</code> (in radians). |
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parents:
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|
8492 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8493 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8494 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8495 |
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Franklin Schmidt <fschmidt@gmail.com>
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|
8496 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
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|
8497 <hr><h3><a name="pdf-math.atan"><code>math.atan (y [, x])</code></a></h3> |
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Franklin Schmidt <fschmidt@gmail.com>
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|
8498 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8499 |
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Franklin Schmidt <fschmidt@gmail.com>
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|
8500 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
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|
8501 |
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|
8502 Returns the arc tangent of <code>y/x</code> (in radians), |
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parents:
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|
8503 but uses the signs of both parameters to find the |
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parents:
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changeset
|
8504 quadrant of the result. |
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parents:
diff
changeset
|
8505 (It also handles correctly the case of <code>x</code> being zero.) |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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|
8506 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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|
8507 |
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Franklin Schmidt <fschmidt@gmail.com>
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|
8508 <p> |
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|
8509 The default value for <code>x</code> is 1, |
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parents:
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|
8510 so that the call <code>math.atan(y)</code> |
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parents:
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|
8511 returns the arc tangent of <code>y</code>. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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changeset
|
8512 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8513 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8514 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8515 |
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Franklin Schmidt <fschmidt@gmail.com>
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changeset
|
8516 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
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|
8517 <hr><h3><a name="pdf-math.ceil"><code>math.ceil (x)</code></a></h3> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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changeset
|
8518 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8519 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8520 <p> |
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parents:
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|
8521 Returns the smallest integral value larger than or equal to <code>x</code>. |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8522 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8523 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8524 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8525 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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changeset
|
8526 <p> |
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|
8527 <hr><h3><a name="pdf-math.cos"><code>math.cos (x)</code></a></h3> |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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changeset
|
8528 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8529 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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changeset
|
8530 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8531 Returns the cosine of <code>x</code> (assumed to be in radians). |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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changeset
|
8532 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8533 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8534 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8535 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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changeset
|
8536 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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|
8537 <hr><h3><a name="pdf-math.deg"><code>math.deg (x)</code></a></h3> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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changeset
|
8538 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8539 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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changeset
|
8540 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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changeset
|
8541 Converts the angle <code>x</code> from radians to degrees. |
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parents:
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changeset
|
8542 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8543 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8544 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8545 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8546 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
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|
8547 <hr><h3><a name="pdf-math.exp"><code>math.exp (x)</code></a></h3> |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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changeset
|
8548 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8549 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8550 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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changeset
|
8551 Returns the value <em>e<sup>x</sup></em> |
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parents:
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changeset
|
8552 (where <code>e</code> is the base of natural logarithms). |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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|
8553 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8554 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8555 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8556 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8557 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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|
8558 <hr><h3><a name="pdf-math.floor"><code>math.floor (x)</code></a></h3> |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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changeset
|
8559 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8560 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8561 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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changeset
|
8562 Returns the largest integral value smaller than or equal to <code>x</code>. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8563 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8564 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8565 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8566 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8567 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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changeset
|
8568 <hr><h3><a name="pdf-math.fmod"><code>math.fmod (x, y)</code></a></h3> |
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parents:
diff
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|
8569 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8570 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8571 <p> |
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parents:
diff
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|
8572 Returns the remainder of the division of <code>x</code> by <code>y</code> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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changeset
|
8573 that rounds the quotient towards zero. (integer/float) |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
8574 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
8575 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8576 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8577 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8578 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
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|
8579 <hr><h3><a name="pdf-math.huge"><code>math.huge</code></a></h3> |
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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 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8582 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
8583 The float value <code>HUGE_VAL</code>, |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8584 a value larger than any other numerical value. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8585 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8586 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8587 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8588 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8589 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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|
8590 <hr><h3><a name="pdf-math.log"><code>math.log (x [, base])</code></a></h3> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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|
8591 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8592 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8593 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
8594 Returns the logarithm of <code>x</code> in the given base. |
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parents:
diff
changeset
|
8595 The default for <code>base</code> is <em>e</em> |
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parents:
diff
changeset
|
8596 (so that the function returns the natural logarithm of <code>x</code>). |
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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 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8599 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8600 |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8601 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
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|
8602 <hr><h3><a name="pdf-math.max"><code>math.max (x, ···)</code></a></h3> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8603 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8604 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8605 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8606 Returns the argument with the maximum value, |
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parents:
diff
changeset
|
8607 according to the Lua operator <code><</code>. (integer/float) |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8608 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8609 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8610 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8611 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8612 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8613 <hr><h3><a name="pdf-math.maxinteger"><code>math.maxinteger</code></a></h3> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8614 An integer with the maximum value for an integer. |
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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 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8617 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8618 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8619 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
8620 <hr><h3><a name="pdf-math.min"><code>math.min (x, ···)</code></a></h3> |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8621 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8622 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8623 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8624 Returns the argument with the minimum value, |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8625 according to the Lua operator <code><</code>. (integer/float) |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8626 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8627 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8628 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8629 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8630 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8631 <hr><h3><a name="pdf-math.mininteger"><code>math.mininteger</code></a></h3> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8632 An integer with the minimum value for an integer. |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8633 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8634 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
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 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8638 <hr><h3><a name="pdf-math.modf"><code>math.modf (x)</code></a></h3> |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8639 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8640 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8641 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8642 Returns the integral part of <code>x</code> and the fractional part of <code>x</code>. |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8643 Its second result is always a float. |
e01cddba3433
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
add manual.html as copy of Lua 5.3 Reference Manual
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.pi"><code>math.pi</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
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8651 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8652 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8653 The value of <em>π</em>. |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8654 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8655 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8656 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8657 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8658 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8659 <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
|
8660 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8661 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8662 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8663 Converts the angle <code>x</code> from degrees to radians. |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8664 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8665 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8666 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8667 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8668 <p> |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8669 <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
|
8670 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8671 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8672 <p> |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8673 When called without arguments, |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8674 returns a pseudo-random float with uniform distribution |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8675 in the range <em>[0,1)</em>. |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8676 When called with two integers <code>m</code> and <code>n</code>, |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8677 <code>math.random</code> returns a pseudo-random integer |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8678 with uniform distribution in the range <em>[m, n]</em>. |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8679 (The value <em>m-n</em> cannot be negative and must fit in a Lua integer.) |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8680 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
|
8681 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8682 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8683 <p> |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8684 This function is an interface to the underling |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8685 pseudo-random generator function provided by C. |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8686 No guarantees can be given for its statistical properties. |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8687 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8688 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8689 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8690 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8691 <p> |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8692 <hr><h3><a name="pdf-math.randomseed"><code>math.randomseed (x)</code></a></h3> |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8693 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8694 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8695 <p> |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8696 Sets <code>x</code> as the "seed" |
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|
8697 for the pseudo-random generator: |
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|
8698 equal seeds produce equal sequences of numbers. |
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|
8699 |
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diff
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|
8700 |
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diff
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|
8701 |
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|
8702 |
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|
8703 <p> |
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|
8704 <hr><h3><a name="pdf-math.sin"><code>math.sin (x)</code></a></h3> |
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|
8705 |
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|
8706 |
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|
8707 <p> |
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|
8708 Returns the sine of <code>x</code> (assumed to be in radians). |
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|
8709 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
8710 |
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diff
changeset
|
8711 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
8712 |
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|
8713 <p> |
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|
8714 <hr><h3><a name="pdf-math.sqrt"><code>math.sqrt (x)</code></a></h3> |
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|
8715 |
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|
8716 |
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|
8717 <p> |
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|
8718 Returns the square root of <code>x</code>. |
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|
8719 (You can also use the expression <code>x^0.5</code> to compute this value.) |
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|
8720 |
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|
8721 |
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parents:
diff
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|
8722 |
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diff
changeset
|
8723 |
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|
8724 <p> |
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|
8725 <hr><h3><a name="pdf-math.tan"><code>math.tan (x)</code></a></h3> |
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|
8726 |
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|
8727 |
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|
8728 <p> |
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|
8729 Returns the tangent of <code>x</code> (assumed to be in radians). |
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|
8730 |
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diff
changeset
|
8731 |
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parents:
diff
changeset
|
8732 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8733 |
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|
8734 <p> |
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|
8735 <hr><h3><a name="pdf-math.tointeger"><code>math.tointeger (x)</code></a></h3> |
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|
8736 |
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changeset
|
8737 |
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changeset
|
8738 <p> |
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|
8739 If the value <code>x</code> is convertible to an integer, |
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changeset
|
8740 returns that integer. |
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|
8741 Otherwise, returns <b>nil</b>. |
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|
8742 |
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diff
changeset
|
8743 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8744 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8745 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
8746 <p> |
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|
8747 <hr><h3><a name="pdf-math.type"><code>math.type (x)</code></a></h3> |
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|
8748 |
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parents:
diff
changeset
|
8749 |
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Franklin Schmidt <fschmidt@gmail.com>
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|
8750 <p> |
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|
8751 Returns "<code>integer</code>" if <code>x</code> is an integer, |
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parents:
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|
8752 "<code>float</code>" if it is a float, |
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parents:
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|
8753 or <b>nil</b> if <code>x</code> is not a number. |
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parents:
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|
8754 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
8755 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8756 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8757 |
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Franklin Schmidt <fschmidt@gmail.com>
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changeset
|
8758 <p> |
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|
8759 <hr><h3><a name="pdf-math.ult"><code>math.ult (m, n)</code></a></h3> |
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parents:
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changeset
|
8760 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8761 |
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diff
changeset
|
8762 <p> |
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changeset
|
8763 Returns a boolean, |
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parents:
diff
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|
8764 true if integer <code>m</code> is below integer <code>n</code> when |
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|
8765 they are compared as unsigned integers. |
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diff
changeset
|
8766 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8767 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8768 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8769 |
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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 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8772 |
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|
8773 <h2>6.8 – <a name="6.8">Input and Output Facilities</a></h2> |
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|
8774 |
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Franklin Schmidt <fschmidt@gmail.com>
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changeset
|
8775 <p> |
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changeset
|
8776 The I/O library provides two different styles for file manipulation. |
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parents:
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|
8777 The first one uses implicit file handles; |
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parents:
diff
changeset
|
8778 that is, there are operations to set a default input file and a |
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parents:
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changeset
|
8779 default output file, |
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parents:
diff
changeset
|
8780 and all input/output operations are over these default files. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8781 The second style uses explicit file handles. |
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parents:
diff
changeset
|
8782 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8783 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8784 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8785 When using implicit file handles, |
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parents:
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changeset
|
8786 all operations are supplied by table <a name="pdf-io"><code>io</code></a>. |
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parents:
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changeset
|
8787 When using explicit file handles, |
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parents:
diff
changeset
|
8788 the operation <a href="#pdf-io.open"><code>io.open</code></a> returns a file handle |
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parents:
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changeset
|
8789 and then all operations are supplied as methods of the file handle. |
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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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parents:
diff
changeset
|
8793 The table <code>io</code> also provides |
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parents:
diff
changeset
|
8794 three predefined file handles with their usual meanings from C: |
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parents:
diff
changeset
|
8795 <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>. |
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parents:
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changeset
|
8796 The I/O library never closes these files. |
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parents:
diff
changeset
|
8797 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8798 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8799 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8800 Unless otherwise stated, |
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parents:
diff
changeset
|
8801 all I/O functions return <b>nil</b> on failure |
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parents:
diff
changeset
|
8802 (plus an error message as a second result and |
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parents:
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changeset
|
8803 a system-dependent error code as a third result) |
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parents:
diff
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|
8804 and some value different from <b>nil</b> on success. |
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parents:
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changeset
|
8805 On non-POSIX systems, |
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parents:
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changeset
|
8806 the computation of the error message and error code |
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diff
changeset
|
8807 in case of errors |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8808 may be not thread safe, |
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parents:
diff
changeset
|
8809 because they rely on the global C variable <code>errno</code>. |
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parents:
diff
changeset
|
8810 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8811 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8812 <p> |
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parents:
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changeset
|
8813 <hr><h3><a name="pdf-io.close"><code>io.close ([file])</code></a></h3> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8814 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8815 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8816 <p> |
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parents:
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changeset
|
8817 Equivalent to <code>file:close()</code>. |
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parents:
diff
changeset
|
8818 Without a <code>file</code>, closes the default output file. |
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parents:
diff
changeset
|
8819 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8820 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8821 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8822 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8823 <p> |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8824 <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
|
8825 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8826 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8827 <p> |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8828 Equivalent to <code>io.output():flush()</code>. |
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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.input"><code>io.input ([file])</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
|
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> |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8838 When called with a file name, it opens the named file (in text 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 sets its handle as the default input file. |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8840 When called with a file handle, |
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
diff
changeset
|
8841 it simply sets this file handle as the default input file. |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8842 When called without parameters, |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8843 it returns the current default input file. |
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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 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8846 <p> |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
8847 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
|
8848 instead of returning an error code. |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8849 |
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 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8853 <p> |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8854 <hr><h3><a name="pdf-io.lines"><code>io.lines ([filename ···])</code></a></h3> |
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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 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8858 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
|
8859 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
|
8860 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
|
8861 When the iterator function detects the end of file, |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8862 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
|
8863 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8864 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8865 <p> |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8866 The call <code>io.lines()</code> (with no file name) is equivalent |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8867 to <code>io.input():lines("*l")</code>; |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8868 that is, it iterates over the lines of the default input file. |
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parents:
diff
changeset
|
8869 In this case it does not close the file when the loop ends. |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8870 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8871 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8872 <p> |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8873 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
|
8874 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
|
8875 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8876 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8877 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8878 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8879 <p> |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8880 <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
|
8881 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8882 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8883 <p> |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8884 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
|
8885 in the mode specified in the string <code>mode</code>. |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8886 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
|
8887 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
|
8888 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8889 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8890 <p> |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8891 The <code>mode</code> string can be any of the following: |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8892 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8893 <ul> |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8894 <li><b>"<code>r</code>": </b> read mode (the default);</li> |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8895 <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
|
8896 <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
|
8897 <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
|
8898 <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
|
8899 <li><b>"<code>a+</code>": </b> append update mode, previous data is preserved, |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8900 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
|
8901 </ul><p> |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8902 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
|
8903 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
|
8904 |
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 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8908 <p> |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8909 <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
|
8910 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8911 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8912 <p> |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8913 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
|
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 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8918 <p> |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8919 <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
|
8920 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8921 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8922 <p> |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8923 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
|
8924 on all platforms. |
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 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
|
8929 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
|
8930 (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
|
8931 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
|
8932 (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
|
8933 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8934 |
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 <p> |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8938 <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
|
8939 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8940 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8941 <p> |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8942 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
|
8943 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8944 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8945 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8946 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8947 <p> |
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|
8948 <hr><h3><a name="pdf-io.tmpfile"><code>io.tmpfile ()</code></a></h3> |
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|
8949 |
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diff
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|
8950 |
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diff
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|
8951 <p> |
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|
8952 Returns a handle for a temporary file. |
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|
8953 This file is opened in update mode |
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|
8954 and it is automatically removed when the program ends. |
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|
8955 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
8956 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8957 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
8958 |
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|
8959 <p> |
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|
8960 <hr><h3><a name="pdf-io.type"><code>io.type (obj)</code></a></h3> |
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|
8961 |
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|
8962 |
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|
8963 <p> |
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|
8964 Checks whether <code>obj</code> is a valid file handle. |
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|
8965 Returns the string <code>"file"</code> if <code>obj</code> is an open file handle, |
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|
8966 <code>"closed file"</code> if <code>obj</code> is a closed file handle, |
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|
8967 or <b>nil</b> if <code>obj</code> is not a file handle. |
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|
8968 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
8969 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8970 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
8971 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
8972 <p> |
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|
8973 <hr><h3><a name="pdf-io.write"><code>io.write (···)</code></a></h3> |
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|
8974 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
8975 |
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Franklin Schmidt <fschmidt@gmail.com>
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|
8976 <p> |
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|
8977 Equivalent to <code>io.output():write(···)</code>. |
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|
8978 |
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diff
changeset
|
8979 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8980 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8981 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
8982 <p> |
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|
8983 <hr><h3><a name="pdf-file:close"><code>file:close ()</code></a></h3> |
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|
8984 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8985 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
8986 <p> |
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|
8987 Closes <code>file</code>. |
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|
8988 Note that files are automatically closed when |
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|
8989 their handles are garbage collected, |
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|
8990 but that takes an unpredictable amount of time to happen. |
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changeset
|
8991 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8992 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
8993 <p> |
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|
8994 When closing a file handle created with <a href="#pdf-io.popen"><code>io.popen</code></a>, |
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|
8995 <a href="#pdf-file:close"><code>file:close</code></a> returns the same values |
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|
8996 returned by <a href="#pdf-os.execute"><code>os.execute</code></a>. |
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|
8997 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
8998 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
8999 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9000 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
9001 <p> |
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|
9002 <hr><h3><a name="pdf-file:flush"><code>file:flush ()</code></a></h3> |
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|
9003 |
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Franklin Schmidt <fschmidt@gmail.com>
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changeset
|
9004 |
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|
9005 <p> |
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|
9006 Saves any written data to <code>file</code>. |
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|
9007 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
9008 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
9009 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
9010 |
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Franklin Schmidt <fschmidt@gmail.com>
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|
9011 <p> |
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|
9012 <hr><h3><a name="pdf-file:lines"><code>file:lines (···)</code></a></h3> |
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|
9013 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
9014 |
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|
9015 <p> |
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|
9016 Returns an iterator function that, |
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|
9017 each time it is called, |
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parents:
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|
9018 reads the file according to the given formats. |
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|
9019 When no format is given, |
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|
9020 uses "<code>l</code>" as a default. |
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|
9021 As an example, the construction |
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|
9022 |
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|
9023 <pre> |
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|
9024 for c in file:lines(1) do <em>body</em> end |
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|
9025 </pre><p> |
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parents:
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|
9026 will iterate over all characters of the file, |
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diff
changeset
|
9027 starting at the current position. |
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parents:
diff
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|
9028 Unlike <a href="#pdf-io.lines"><code>io.lines</code></a>, this function does not close the file |
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Franklin Schmidt <fschmidt@gmail.com>
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|
9029 when the loop ends. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9030 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
9031 |
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Franklin Schmidt <fschmidt@gmail.com>
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|
9032 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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|
9033 In case of errors this function raises the error, |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
9034 instead of returning an error code. |
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parents:
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changeset
|
9035 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
9036 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9037 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
9038 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9039 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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|
9040 <hr><h3><a name="pdf-file:read"><code>file:read (···)</code></a></h3> |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
9041 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9042 |
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Franklin Schmidt <fschmidt@gmail.com>
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changeset
|
9043 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
9044 Reads the file <code>file</code>, |
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parents:
diff
changeset
|
9045 according to the given formats, which specify what to read. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9046 For each format, |
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parents:
diff
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|
9047 the function returns a string or a number with the characters read, |
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parents:
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changeset
|
9048 or <b>nil</b> if it cannot read data with the specified format. |
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parents:
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changeset
|
9049 (In this latter case, |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9050 the function does not read subsequent formats.) |
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parents:
diff
changeset
|
9051 When called without formats, |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9052 it uses a default format that reads the next line |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9053 (see below). |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9054 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9055 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9056 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
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changeset
|
9057 The available formats are |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9058 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9059 <ul> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9060 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9061 <li><b>"<code>n</code>": </b> |
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parents:
diff
changeset
|
9062 reads a numeral and returns it as a float or an integer, |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9063 following the lexical conventions of Lua. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9064 (The numeral may have leading spaces and a sign.) |
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parents:
diff
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|
9065 This format always reads the longest input sequence that |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9066 is a valid prefix for a number; |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9067 if that prefix does not form a valid number |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9068 (e.g., an empty string, "<code>0x</code>", or "<code>3.4e-</code>"), |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9069 it is discarded and the function returns <b>nil</b>. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9070 </li> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9071 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9072 <li><b>"<code>i</code>": </b> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9073 reads an integral number and returns it as an integer. |
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9074 </li> |
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|
9075 |
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9076 <li><b>"<code>a</code>": </b> |
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9077 reads the whole file, starting at the current position. |
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9078 On end of file, it returns the empty string. |
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9079 </li> |
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|
9080 |
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9081 <li><b>"<code>l</code>": </b> |
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9082 reads the next line skipping the end of line, |
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9083 returning <b>nil</b> on end of file. |
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9084 This is the default format. |
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9085 </li> |
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|
9086 |
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9087 <li><b>"<code>L</code>": </b> |
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9088 reads the next line keeping the end-of-line character (if present), |
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9089 returning <b>nil</b> on end of file. |
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9090 </li> |
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|
9091 |
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9092 <li><b><em>number</em>: </b> |
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9093 reads a string with up to this number of bytes, |
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9094 returning <b>nil</b> on end of file. |
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9095 If <code>number</code> is zero, |
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9096 it reads nothing and returns an empty string, |
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9097 or <b>nil</b> on end of file. |
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9098 </li> |
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|
9099 |
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|
9100 </ul><p> |
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|
9101 The formats "<code>l</code>" and "<code>L</code>" should be used only for text files. |
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|
9102 |
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|
9103 |
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|
9104 |
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|
9105 |
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|
9106 <p> |
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9107 <hr><h3><a name="pdf-file:seek"><code>file:seek ([whence [, offset]])</code></a></h3> |
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|
9108 |
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|
9109 |
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9110 <p> |
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9111 Sets and gets the file position, |
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9112 measured from the beginning of the file, |
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9113 to the position given by <code>offset</code> plus a base |
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9114 specified by the string <code>whence</code>, as follows: |
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|
9115 |
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|
9116 <ul> |
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9117 <li><b>"<code>set</code>": </b> base is position 0 (beginning of the file);</li> |
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9118 <li><b>"<code>cur</code>": </b> base is current position;</li> |
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9119 <li><b>"<code>end</code>": </b> base is end of file;</li> |
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9120 </ul><p> |
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9121 In case of success, <code>seek</code> returns the final file position, |
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9122 measured in bytes from the beginning of the file. |
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9123 If <code>seek</code> fails, it returns <b>nil</b>, |
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9124 plus a string describing the error. |
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|
9125 |
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|
9126 |
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|
9127 <p> |
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9128 The default value for <code>whence</code> is <code>"cur"</code>, |
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9129 and for <code>offset</code> is 0. |
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9130 Therefore, the call <code>file:seek()</code> returns the current |
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9131 file position, without changing it; |
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9132 the call <code>file:seek("set")</code> sets the position to the |
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9133 beginning of the file (and returns 0); |
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9134 and the call <code>file:seek("end")</code> sets the position to the |
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|
9135 end of the file, and returns its size. |
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|
9136 |
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|
9137 |
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changeset
|
9138 |
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|
9139 |
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|
9140 <p> |
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|
9141 <hr><h3><a name="pdf-file:setvbuf"><code>file:setvbuf (mode [, size])</code></a></h3> |
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|
9142 |
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|
9143 |
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|
9144 <p> |
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9145 Sets the buffering mode for an output file. |
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9146 There are three available modes: |
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|
9147 |
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|
9148 <ul> |
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|
9149 |
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9150 <li><b>"<code>no</code>": </b> |
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|
9151 no buffering; the result of any output operation appears immediately. |
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|
9152 </li> |
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|
9153 |
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|
9154 <li><b>"<code>full</code>": </b> |
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|
9155 full buffering; output operation is performed only |
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|
9156 when the buffer is full or when |
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|
9157 you explicitly <code>flush</code> the file (see <a href="#pdf-io.flush"><code>io.flush</code></a>). |
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|
9158 </li> |
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|
9159 |
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|
9160 <li><b>"<code>line</code>": </b> |
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|
9161 line buffering; output is buffered until a newline is output |
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|
9162 or there is any input from some special files |
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|
9163 (such as a terminal device). |
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|
9164 </li> |
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|
9165 |
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|
9166 </ul><p> |
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9167 For the last two cases, <code>size</code> |
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9168 specifies the size of the buffer, in bytes. |
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9169 The default is an appropriate size. |
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|
9170 |
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|
9171 |
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|
9172 |
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|
9173 |
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9174 <p> |
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9175 <hr><h3><a name="pdf-file:write"><code>file:write (···)</code></a></h3> |
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9176 |
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|
9177 |
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9178 <p> |
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9179 Writes the value of each of its arguments to <code>file</code>. |
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9180 The arguments must be strings or numbers. |
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9181 |
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|
9182 |
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9183 <p> |
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9184 In case of success, this function returns <code>file</code>. |
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9185 Otherwise it returns <b>nil</b> plus a string describing the error. |
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|
9186 |
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|
9187 |
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|
9188 |
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|
9189 |
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changeset
|
9190 |
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|
9191 |
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|
9192 |
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9193 <h2>6.9 – <a name="6.9">Operating System Facilities</a></h2> |
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9194 |
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9195 <p> |
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9196 This library is implemented through table <a name="pdf-os"><code>os</code></a>. |
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|
9197 |
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|
9198 |
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|
9199 <p> |
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9200 <hr><h3><a name="pdf-os.clock"><code>os.clock ()</code></a></h3> |
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|
9201 |
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|
9202 |
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|
9203 <p> |
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9204 Returns an approximation of the amount in seconds of CPU time |
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9205 used by the program. |
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|
9206 |
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diff
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|
9207 |
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diff
changeset
|
9208 |
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|
9209 |
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|
9210 <p> |
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9211 <hr><h3><a name="pdf-os.date"><code>os.date ([format [, time]])</code></a></h3> |
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9212 |
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|
9213 |
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9214 <p> |
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9215 Returns a string or a table containing date and time, |
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9216 formatted according to the given string <code>format</code>. |
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9217 |
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|
9218 |
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|
9219 <p> |
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9220 If the <code>time</code> argument is present, |
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9221 this is the time to be formatted |
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9222 (see the <a href="#pdf-os.time"><code>os.time</code></a> function for a description of this value). |
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9223 Otherwise, <code>date</code> formats the current time. |
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9224 |
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|
9225 |
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9226 <p> |
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9227 If <code>format</code> starts with '<code>!</code>', |
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9228 then the date is formatted in Coordinated Universal Time. |
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9229 After this optional character, |
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9230 if <code>format</code> is the string "<code>*t</code>", |
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9231 then <code>date</code> returns a table with the following fields: |
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9232 <code>year</code> (four digits), <code>month</code> (1–12), <code>day</code> (1–31), |
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9233 <code>hour</code> (0–23), <code>min</code> (0–59), <code>sec</code> (0–61), |
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9234 <code>wday</code> (weekday, Sunday is 1), |
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9235 <code>yday</code> (day of the year), |
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9236 and <code>isdst</code> (daylight saving flag, a boolean). |
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9237 This last field may be absent |
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9238 if the information is not available. |
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|
9239 |
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|
9240 |
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|
9241 <p> |
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9242 If <code>format</code> is not "<code>*t</code>", |
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9243 then <code>date</code> returns the date as a string, |
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9244 formatted according to the same rules as the ISO C function <code>strftime</code>. |
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|
9245 |
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|
9246 |
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|
9247 <p> |
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9248 When called without arguments, |
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9249 <code>date</code> returns a reasonable date and time representation that depends on |
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9250 the host system and on the current locale |
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9251 (that is, <code>os.date()</code> is equivalent to <code>os.date("%c")</code>). |
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|
9252 |
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|
9253 |
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|
9254 <p> |
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|
9255 On non-POSIX systems, |
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9256 this function may be not thread safe |
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9257 because of its reliance on C function <code>gmtime</code> and C function <code>localtime</code>. |
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|
9258 |
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|
9259 |
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|
9260 |
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|
9261 |
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|
9262 <p> |
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9263 <hr><h3><a name="pdf-os.difftime"><code>os.difftime (t2, t1)</code></a></h3> |
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|
9264 |
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|
9265 |
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|
9266 <p> |
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|
9267 Returns the difference, in seconds, |
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|
9268 from time <code>t1</code> to time <code>t2</code> |
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|
9269 (where the times are values returned by <a href="#pdf-os.time"><code>os.time</code></a>). |
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|
9270 In POSIX, Windows, and some other systems, |
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9271 this value is exactly <code>t2</code><em>-</em><code>t1</code>. |
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|
9272 |
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|
9273 |
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diff
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|
9274 |
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diff
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|
9275 |
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|
9276 <p> |
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|
9277 <hr><h3><a name="pdf-os.execute"><code>os.execute ([command])</code></a></h3> |
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|
9278 |
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|
9279 |
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|
9280 <p> |
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9281 This function is equivalent to the ISO C function <code>system</code>. |
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9282 It passes <code>command</code> to be executed by an operating system shell. |
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9283 Its first result is <b>true</b> |
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9284 if the command terminated successfully, |
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|
9285 or <b>nil</b> otherwise. |
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9286 After this first result |
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9287 the function returns a string plus a number, |
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|
9288 as follows: |
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|
9289 |
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|
9290 <ul> |
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|
9291 |
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|
9292 <li><b>"<code>exit</code>": </b> |
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9293 the command terminated normally; |
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9294 the following number is the exit status of the command. |
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|
9295 </li> |
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|
9296 |
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9297 <li><b>"<code>signal</code>": </b> |
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9298 the command was terminated by a signal; |
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|
9299 the following number is the signal that terminated the command. |
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|
9300 </li> |
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|
9301 |
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|
9302 </ul> |
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|
9303 |
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|
9304 <p> |
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|
9305 When called without a <code>command</code>, |
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9306 <code>os.execute</code> returns a boolean that is true if a shell is available. |
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|
9307 |
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changeset
|
9308 |
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diff
changeset
|
9309 |
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changeset
|
9310 |
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|
9311 <p> |
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9312 <hr><h3><a name="pdf-os.exit"><code>os.exit ([code [, close]])</code></a></h3> |
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|
9313 |
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changeset
|
9314 |
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changeset
|
9315 <p> |
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|
9316 Calls the ISO C function <code>exit</code> to terminate the host program. |
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|
9317 If <code>code</code> is <b>true</b>, |
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|
9318 the returned status is <code>EXIT_SUCCESS</code>; |
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|
9319 if <code>code</code> is <b>false</b>, |
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|
9320 the returned status is <code>EXIT_FAILURE</code>; |
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changeset
|
9321 if <code>code</code> is a number, |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9322 the returned status is this number. |
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parents:
diff
changeset
|
9323 The default value for <code>code</code> is <b>true</b>. |
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parents:
diff
changeset
|
9324 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9325 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9326 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9327 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
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
9328 closes the Lua state before exiting. |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
9329 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9330 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9331 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9332 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9333 <p> |
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parents:
diff
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|
9334 <hr><h3><a name="pdf-os.getenv"><code>os.getenv (varname)</code></a></h3> |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
9335 |
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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 Returns the value of the process environment variable <code>varname</code>, |
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parents:
diff
changeset
|
9339 or <b>nil</b> if the variable is not defined. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
9340 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9341 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9342 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9343 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9344 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
9345 <hr><h3><a name="pdf-os.remove"><code>os.remove (filename)</code></a></h3> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9346 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9347 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9348 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
9349 Deletes the file (or empty directory, on POSIX systems) |
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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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|
9350 with the given name. |
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parents:
diff
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|
9351 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
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|
9352 plus a string describing the error and the error code. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9353 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9354 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9355 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9356 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9357 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
9358 <hr><h3><a name="pdf-os.rename"><code>os.rename (oldname, newname)</code></a></h3> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9359 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9360 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9361 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
9362 Renames file or directory named <code>oldname</code> to <code>newname</code>. |
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parents:
diff
changeset
|
9363 If this function fails, it returns <b>nil</b>, |
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parents:
diff
changeset
|
9364 plus a string describing the error and the error code. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9365 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9366 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9367 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9368 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
9369 <p> |
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|
9370 <hr><h3><a name="pdf-os.setlocale"><code>os.setlocale (locale [, category])</code></a></h3> |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
9371 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9372 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
9373 <p> |
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|
9374 Sets the current locale of the program. |
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diff
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|
9375 <code>locale</code> is a system-dependent string specifying a locale; |
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parents:
diff
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|
9376 <code>category</code> is an optional string describing which category to change: |
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parents:
diff
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|
9377 <code>"all"</code>, <code>"collate"</code>, <code>"ctype"</code>, |
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diff
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|
9378 <code>"monetary"</code>, <code>"numeric"</code>, or <code>"time"</code>; |
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|
9379 the default category is <code>"all"</code>. |
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changeset
|
9380 The function returns the name of the new locale, |
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parents:
diff
changeset
|
9381 or <b>nil</b> if the request cannot be honored. |
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diff
changeset
|
9382 |
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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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parents:
diff
changeset
|
9385 If <code>locale</code> is the empty string, |
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parents:
diff
changeset
|
9386 the current locale is set to an implementation-defined native locale. |
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parents:
diff
changeset
|
9387 If <code>locale</code> is the string "<code>C</code>", |
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parents:
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changeset
|
9388 the current locale is set to the standard C locale. |
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diff
changeset
|
9389 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9390 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
9391 <p> |
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parents:
diff
changeset
|
9392 When called with <b>nil</b> as the first argument, |
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parents:
diff
changeset
|
9393 this function only returns the name of the current locale |
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diff
changeset
|
9394 for the given category. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9395 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9396 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
9397 <p> |
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diff
changeset
|
9398 This function may be not thread safe |
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parents:
diff
changeset
|
9399 because of its reliance on C function <code>setlocale</code>. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9400 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9401 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9402 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9403 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
9404 <p> |
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parents:
diff
changeset
|
9405 <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
|
9406 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9407 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9408 <p> |
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parents:
diff
changeset
|
9409 Returns the current time when called without arguments, |
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parents:
diff
changeset
|
9410 or a time representing the date and time specified by the given table. |
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parents:
diff
changeset
|
9411 This table must have fields <code>year</code>, <code>month</code>, and <code>day</code>, |
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diff
changeset
|
9412 and may have fields |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9413 <code>hour</code> (default is 12), |
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parents:
diff
changeset
|
9414 <code>min</code> (default is 0), |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9415 <code>sec</code> (default is 0), |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9416 and <code>isdst</code> (default is <b>nil</b>). |
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parents:
diff
changeset
|
9417 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>
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diff
changeset
|
9418 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9419 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9420 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9421 The returned value is a number, whose meaning depends on your system. |
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parents:
diff
changeset
|
9422 In POSIX, Windows, and some other systems, |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9423 this number counts the number |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9424 of seconds since some given start time (the "epoch"). |
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parents:
diff
changeset
|
9425 In other systems, the meaning is not specified, |
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diff
changeset
|
9426 and the number returned by <code>time</code> can be used only as an argument to |
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parents:
diff
changeset
|
9427 <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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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9428 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9429 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9430 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9431 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9432 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9433 <hr><h3><a name="pdf-os.tmpname"><code>os.tmpname ()</code></a></h3> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9434 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9435 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9436 <p> |
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diff
changeset
|
9437 Returns a string with a file name that can |
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diff
changeset
|
9438 be used for a temporary file. |
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parents:
diff
changeset
|
9439 The file must be explicitly opened before its use |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
9440 and explicitly removed when no longer needed. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9441 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9442 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9443 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
9444 On POSIX systems, |
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|
9445 this function also creates a file with that name, |
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diff
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|
9446 to avoid security risks. |
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parents:
diff
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|
9447 (Someone else might create the file with wrong permissions |
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|
9448 in the time between getting the name and creating the file.) |
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|
9449 You still have to open the file to use it |
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|
9450 and to remove it (even if you do not use it). |
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diff
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|
9451 |
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diff
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|
9452 |
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diff
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|
9453 <p> |
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diff
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|
9454 When possible, |
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diff
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|
9455 you may prefer to use <a href="#pdf-io.tmpfile"><code>io.tmpfile</code></a>, |
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diff
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|
9456 which automatically removes the file when the program ends. |
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diff
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|
9457 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9458 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9459 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9460 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9461 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9462 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9463 |
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diff
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|
9464 <h2>6.10 – <a name="6.10">The Debug Library</a></h2> |
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|
9465 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
9466 <p> |
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parents:
diff
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|
9467 This library provides |
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diff
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|
9468 the functionality of the debug interface (<a href="#4.9">§4.9</a>) to Lua programs. |
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|
9469 You should exert care when using this library. |
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diff
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|
9470 Several of its functions |
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|
9471 violate basic assumptions about Lua code |
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|
9472 (e.g., that variables local to a function |
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parents:
diff
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|
9473 cannot be accessed from outside; |
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diff
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|
9474 that userdata metatables cannot be changed by Lua code; |
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diff
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|
9475 that Lua programs do not crash) |
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|
9476 and therefore can compromise otherwise secure code. |
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|
9477 Moreover, some functions in this library may be slow. |
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changeset
|
9478 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
9479 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
9480 <p> |
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|
9481 All functions in this library are provided |
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|
9482 inside the <a name="pdf-debug"><code>debug</code></a> table. |
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parents:
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|
9483 All functions that operate over a thread |
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|
9484 have an optional first argument which is the |
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diff
changeset
|
9485 thread to operate over. |
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|
9486 The default is always the current thread. |
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|
9487 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
9488 |
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changeset
|
9489 <p> |
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|
9490 <hr><h3><a name="pdf-debug.debug"><code>debug.debug ()</code></a></h3> |
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changeset
|
9491 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
9492 |
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diff
changeset
|
9493 <p> |
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|
9494 Enters an interactive mode with the user, |
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|
9495 running each string that the user enters. |
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diff
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|
9496 Using simple commands and other debug facilities, |
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|
9497 the user can inspect global and local variables, |
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diff
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|
9498 change their values, evaluate expressions, and so on. |
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diff
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|
9499 A line containing only the word <code>cont</code> finishes this function, |
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|
9500 so that the caller continues its execution. |
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changeset
|
9501 |
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diff
changeset
|
9502 |
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diff
changeset
|
9503 <p> |
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diff
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|
9504 Note that commands for <code>debug.debug</code> are not lexically nested |
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|
9505 within any function and so have no direct access to local variables. |
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parents:
diff
changeset
|
9506 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
9507 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
9508 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
9509 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
9510 <p> |
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|
9511 <hr><h3><a name="pdf-debug.gethook"><code>debug.gethook ([thread])</code></a></h3> |
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changeset
|
9512 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
9513 |
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changeset
|
9514 <p> |
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|
9515 Returns the current hook settings of the thread, as three values: |
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changeset
|
9516 the current hook function, the current hook mask, |
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diff
changeset
|
9517 and the current hook count |
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parents:
diff
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|
9518 (as set by the <a href="#pdf-debug.sethook"><code>debug.sethook</code></a> function). |
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changeset
|
9519 |
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diff
changeset
|
9520 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
9521 |
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diff
changeset
|
9522 |
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|
9523 <p> |
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|
9524 <hr><h3><a name="pdf-debug.getinfo"><code>debug.getinfo ([thread,] f [, what])</code></a></h3> |
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changeset
|
9525 |
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diff
changeset
|
9526 |
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diff
changeset
|
9527 <p> |
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parents:
diff
changeset
|
9528 Returns a table with information about a function. |
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diff
changeset
|
9529 You can give the function directly |
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parents:
diff
changeset
|
9530 or you can give a number as the value of <code>f</code>, |
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parents:
diff
changeset
|
9531 which means the function running at level <code>f</code> of the call stack |
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parents:
diff
changeset
|
9532 of the given thread: |
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parents:
diff
changeset
|
9533 level 0 is the current function (<code>getinfo</code> itself); |
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parents:
diff
changeset
|
9534 level 1 is the function that called <code>getinfo</code> |
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parents:
diff
changeset
|
9535 (except for tail calls, which do not count on the stack); |
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parents:
diff
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|
9536 and so on. |
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parents:
diff
changeset
|
9537 If <code>f</code> is a number larger than the number of active functions, |
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parents:
diff
changeset
|
9538 then <code>getinfo</code> returns <b>nil</b>. |
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parents:
diff
changeset
|
9539 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9540 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9541 <p> |
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|
9542 The returned table can contain all the fields returned by <a href="#lua_getinfo"><code>lua_getinfo</code></a>, |
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parents:
diff
changeset
|
9543 with the string <code>what</code> describing which fields to fill in. |
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parents:
diff
changeset
|
9544 The default for <code>what</code> is to get all information available, |
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diff
changeset
|
9545 except the table of valid lines. |
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parents:
diff
changeset
|
9546 If present, |
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parents:
diff
changeset
|
9547 the option '<code>f</code>' |
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parents:
diff
changeset
|
9548 adds a field named <code>func</code> with the function itself. |
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parents:
diff
changeset
|
9549 If present, |
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parents:
diff
changeset
|
9550 the option '<code>L</code>' |
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diff
changeset
|
9551 adds a field named <code>activelines</code> with the table of |
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parents:
diff
changeset
|
9552 valid lines. |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9553 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9554 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
9555 <p> |
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parents:
diff
changeset
|
9556 For instance, the expression <code>debug.getinfo(1,"n").name</code> returns |
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parents:
diff
changeset
|
9557 a table with a name for the current function, |
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diff
changeset
|
9558 if a reasonable name can be found, |
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parents:
diff
changeset
|
9559 and the expression <code>debug.getinfo(print)</code> |
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parents:
diff
changeset
|
9560 returns a table with all available information |
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parents:
diff
changeset
|
9561 about the <a href="#pdf-print"><code>print</code></a> function. |
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parents:
diff
changeset
|
9562 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9563 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9564 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9565 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9566 <p> |
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parents:
diff
changeset
|
9567 <hr><h3><a name="pdf-debug.getlocal"><code>debug.getlocal ([thread,] f, local)</code></a></h3> |
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parents:
diff
changeset
|
9568 |
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|
9569 |
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|
9570 <p> |
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|
9571 This function returns the name and the value of the local variable |
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9572 with index <code>local</code> of the function at level <code>f</code> of the stack. |
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9573 This function accesses not only explicit local variables, |
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9574 but also parameters, temporaries, etc. |
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|
9575 |
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|
9576 |
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|
9577 <p> |
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9578 The first parameter or local variable has index 1, and so on, |
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9579 following the order that they are declared in the code, |
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9580 counting only the variables that are active |
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|
9581 in the current scope of the function. |
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9582 Negative indices refer to vararg parameters; |
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9583 -1 is the first vararg parameter. |
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9584 The function returns <b>nil</b> if there is no variable with the given index, |
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9585 and raises an error when called with a level out of range. |
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9586 (You can call <a href="#pdf-debug.getinfo"><code>debug.getinfo</code></a> to check whether the level is valid.) |
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|
9587 |
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|
9588 |
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|
9589 <p> |
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9590 Variable names starting with '<code>(</code>' (open parenthesis) |
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9591 represent variables with no known names |
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9592 (internal variables such as loop control variables, |
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|
9593 and variables from chunks saved without debug information). |
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|
9594 |
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|
9595 |
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|
9596 <p> |
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9597 The parameter <code>f</code> may also be a function. |
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9598 In that case, <code>getlocal</code> returns only the name of function parameters. |
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|
9599 |
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|
9600 |
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|
9601 |
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|
9602 |
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|
9603 <p> |
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9604 <hr><h3><a name="pdf-debug.getmetatable"><code>debug.getmetatable (value)</code></a></h3> |
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|
9605 |
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diff
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|
9606 |
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|
9607 <p> |
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|
9608 Returns the metatable of the given <code>value</code> |
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|
9609 or <b>nil</b> if it does not have a metatable. |
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|
9610 |
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|
9611 |
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diff
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|
9612 |
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|
9613 |
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|
9614 <p> |
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|
9615 <hr><h3><a name="pdf-debug.getregistry"><code>debug.getregistry ()</code></a></h3> |
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|
9616 |
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|
9617 |
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|
9618 <p> |
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|
9619 Returns the registry table (see <a href="#4.5">§4.5</a>). |
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|
9620 |
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|
9621 |
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|
9622 |
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|
9623 |
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|
9624 <p> |
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|
9625 <hr><h3><a name="pdf-debug.getupvalue"><code>debug.getupvalue (f, up)</code></a></h3> |
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|
9626 |
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|
9627 |
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|
9628 <p> |
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|
9629 This function returns the name and the value of the upvalue |
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|
9630 with index <code>up</code> of the function <code>f</code>. |
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|
9631 The function returns <b>nil</b> if there is no upvalue with the given index. |
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|
9632 |
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|
9633 |
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|
9634 <p> |
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9635 Variable names starting with '<code>(</code>' (open parenthesis) |
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|
9636 represent variables with no known names |
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|
9637 (variables from chunks saved without debug information). |
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|
9638 |
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|
9639 |
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|
9640 |
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Franklin Schmidt <fschmidt@gmail.com>
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changeset
|
9641 |
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|
9642 <p> |
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|
9643 <hr><h3><a name="pdf-debug.getuservalue"><code>debug.getuservalue (u)</code></a></h3> |
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|
9644 |
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Franklin Schmidt <fschmidt@gmail.com>
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changeset
|
9645 |
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changeset
|
9646 <p> |
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|
9647 Returns the Lua value associated to <code>u</code>. |
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|
9648 If <code>u</code> is not a userdata, |
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|
9649 returns <b>nil</b>. |
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changeset
|
9650 |
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diff
changeset
|
9651 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
9652 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
9653 |
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|
9654 <p> |
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|
9655 <hr><h3><a name="pdf-debug.sethook"><code>debug.sethook ([thread,] hook, mask [, count])</code></a></h3> |
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|
9656 |
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|
9657 |
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|
9658 <p> |
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|
9659 Sets the given function as a hook. |
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|
9660 The string <code>mask</code> and the number <code>count</code> describe |
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|
9661 when the hook will be called. |
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|
9662 The string mask may have any combination of the following characters, |
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|
9663 with the given meaning: |
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parents:
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changeset
|
9664 |
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changeset
|
9665 <ul> |
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|
9666 <li><b>'<code>c</code>': </b> the hook is called every time Lua calls a function;</li> |
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|
9667 <li><b>'<code>r</code>': </b> the hook is called every time Lua returns from a function;</li> |
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9668 <li><b>'<code>l</code>': </b> the hook is called every time Lua enters a new line of code.</li> |
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changeset
|
9669 </ul><p> |
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changeset
|
9670 Moreover, |
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changeset
|
9671 with a <code>count</code> different from zero, |
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|
9672 the hook is called also after every <code>count</code> instructions. |
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changeset
|
9673 |
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changeset
|
9674 |
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changeset
|
9675 <p> |
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changeset
|
9676 When called without arguments, |
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|
9677 <a href="#pdf-debug.sethook"><code>debug.sethook</code></a> turns off the hook. |
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changeset
|
9678 |
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changeset
|
9679 |
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changeset
|
9680 <p> |
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|
9681 When the hook is called, its first parameter is a string |
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|
9682 describing the event that has triggered its call: |
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changeset
|
9683 <code>"call"</code> (or <code>"tail call"</code>), |
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changeset
|
9684 <code>"return"</code>, |
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|
9685 <code>"line"</code>, and <code>"count"</code>. |
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|
9686 For line events, |
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|
9687 the hook also gets the new line number as its second parameter. |
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changeset
|
9688 Inside a hook, |
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changeset
|
9689 you can call <code>getinfo</code> with level 2 to get more information about |
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changeset
|
9690 the running function |
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changeset
|
9691 (level 0 is the <code>getinfo</code> function, |
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changeset
|
9692 and level 1 is the hook function). |
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|
9693 |
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|
9694 |
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diff
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|
9695 |
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|
9696 |
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|
9697 <p> |
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|
9698 <hr><h3><a name="pdf-debug.setlocal"><code>debug.setlocal ([thread,] level, local, value)</code></a></h3> |
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|
9699 |
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|
9700 |
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|
9701 <p> |
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9702 This function assigns the value <code>value</code> to the local variable |
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9703 with index <code>local</code> of the function at level <code>level</code> of the stack. |
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9704 The function returns <b>nil</b> if there is no local |
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9705 variable with the given index, |
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|
9706 and raises an error when called with a <code>level</code> out of range. |
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|
9707 (You can call <code>getinfo</code> to check whether the level is valid.) |
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9708 Otherwise, it returns the name of the local variable. |
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|
9709 |
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|
9710 |
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|
9711 <p> |
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9712 See <a href="#pdf-debug.getlocal"><code>debug.getlocal</code></a> for more information about |
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9713 variable indices and names. |
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|
9714 |
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|
9715 |
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|
9716 |
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|
9717 |
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|
9718 <p> |
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9719 <hr><h3><a name="pdf-debug.setmetatable"><code>debug.setmetatable (value, table)</code></a></h3> |
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|
9720 |
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|
9721 |
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|
9722 <p> |
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|
9723 Sets the metatable for the given <code>value</code> to the given <code>table</code> |
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|
9724 (which can be <b>nil</b>). |
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|
9725 Returns <code>value</code>. |
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|
9726 |
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|
9727 |
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diff
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|
9728 |
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diff
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|
9729 |
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|
9730 <p> |
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|
9731 <hr><h3><a name="pdf-debug.setupvalue"><code>debug.setupvalue (f, up, value)</code></a></h3> |
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|
9732 |
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diff
changeset
|
9733 |
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|
9734 <p> |
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|
9735 This function assigns the value <code>value</code> to the upvalue |
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|
9736 with index <code>up</code> of the function <code>f</code>. |
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|
9737 The function returns <b>nil</b> if there is no upvalue |
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|
9738 with the given index. |
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parents:
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|
9739 Otherwise, it returns the name of the upvalue. |
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changeset
|
9740 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
9741 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
9742 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
9743 |
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|
9744 <p> |
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|
9745 <hr><h3><a name="pdf-debug.setuservalue"><code>debug.setuservalue (udata, value)</code></a></h3> |
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|
9746 |
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|
9747 |
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|
9748 <p> |
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|
9749 Sets the given <code>value</code> as |
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|
9750 the Lua value associated to the given <code>udata</code>. |
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|
9751 <code>udata</code> must be a full userdata. |
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|
9752 |
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diff
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|
9753 |
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|
9754 <p> |
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|
9755 Returns <code>udata</code>. |
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changeset
|
9756 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
9757 |
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diff
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|
9758 |
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Franklin Schmidt <fschmidt@gmail.com>
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|
9759 |
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Franklin Schmidt <fschmidt@gmail.com>
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|
9760 <p> |
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|
9761 <hr><h3><a name="pdf-debug.traceback"><code>debug.traceback ([thread,] [message [, level]])</code></a></h3> |
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|
9762 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
9763 |
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|
9764 <p> |
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|
9765 If <code>message</code> is present but is neither a string nor <b>nil</b>, |
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|
9766 this function returns <code>message</code> without further processing. |
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|
9767 Otherwise, |
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diff
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|
9768 it returns a string with a traceback of the call stack. |
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|
9769 The optional <code>message</code> string is appended |
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|
9770 at the beginning of the traceback. |
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|
9771 An optional <code>level</code> number tells at which level |
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|
9772 to start the traceback |
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diff
changeset
|
9773 (default is 1, the function calling <code>traceback</code>). |
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changeset
|
9774 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
9775 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
9776 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
9777 |
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changeset
|
9778 <p> |
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|
9779 <hr><h3><a name="pdf-debug.upvalueid"><code>debug.upvalueid (f, n)</code></a></h3> |
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changeset
|
9780 |
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diff
changeset
|
9781 |
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changeset
|
9782 <p> |
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|
9783 Returns a unique identifier (as a light userdata) |
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changeset
|
9784 for the upvalue numbered <code>n</code> |
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changeset
|
9785 from the given function. |
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parents:
diff
changeset
|
9786 |
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diff
changeset
|
9787 |
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changeset
|
9788 <p> |
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parents:
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changeset
|
9789 These unique identifiers allow a program to check whether different |
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diff
changeset
|
9790 closures share upvalues. |
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parents:
diff
changeset
|
9791 Lua closures that share an upvalue |
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changeset
|
9792 (that is, that access a same external local variable) |
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|
9793 will return identical ids for those upvalue indices. |
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changeset
|
9794 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
9795 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
9796 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
9797 |
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changeset
|
9798 <p> |
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changeset
|
9799 <hr><h3><a name="pdf-debug.upvaluejoin"><code>debug.upvaluejoin (f1, n1, f2, n2)</code></a></h3> |
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changeset
|
9800 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
9801 |
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changeset
|
9802 <p> |
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changeset
|
9803 Make the <code>n1</code>-th upvalue of the Lua closure <code>f1</code> |
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|
9804 refer to the <code>n2</code>-th upvalue of the Lua closure <code>f2</code>. |
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changeset
|
9805 |
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diff
changeset
|
9806 |
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diff
changeset
|
9807 |
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diff
changeset
|
9808 |
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diff
changeset
|
9809 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
9810 |
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Franklin Schmidt <fschmidt@gmail.com>
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changeset
|
9811 |
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changeset
|
9812 <h1>7 – <a name="7">Lua Standalone</a></h1> |
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changeset
|
9813 |
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diff
changeset
|
9814 <p> |
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changeset
|
9815 Although Lua has been designed as an extension language, |
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changeset
|
9816 to be embedded in a host C program, |
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changeset
|
9817 it is also frequently used as a standalone language. |
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9818 An interpreter for Lua as a standalone language, |
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9819 called simply <code>lua</code>, |
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9820 is provided with the standard distribution. |
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9821 The standalone interpreter includes |
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9822 all standard libraries, including the debug library. |
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9823 Its usage is: |
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9824 |
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9825 <pre> |
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9826 lua [options] [script [args]] |
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9827 </pre><p> |
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9828 The options are: |
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9829 |
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9830 <ul> |
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9831 <li><b><code>-e <em>stat</em></code>: </b> executes string <em>stat</em>;</li> |
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9832 <li><b><code>-l <em>mod</em></code>: </b> "requires" <em>mod</em>;</li> |
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9833 <li><b><code>-i</code>: </b> enters interactive mode after running <em>script</em>;</li> |
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9834 <li><b><code>-v</code>: </b> prints version information;</li> |
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9835 <li><b><code>-E</code>: </b> ignores environment variables;</li> |
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9836 <li><b><code>--</code>: </b> stops handling options;</li> |
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9837 <li><b><code>-</code>: </b> executes <code>stdin</code> as a file and stops handling options.</li> |
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9838 </ul><p> |
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9839 After handling its options, <code>lua</code> runs the given <em>script</em>. |
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9840 When called without arguments, |
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9841 <code>lua</code> behaves as <code>lua -v -i</code> |
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9842 when the standard input (<code>stdin</code>) is a terminal, |
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9843 and as <code>lua -</code> otherwise. |
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9844 |
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9845 |
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9846 <p> |
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9847 When called without option <code>-E</code>, |
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9848 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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9849 (or <a name="pdf-LUA_INIT"><code>LUA_INIT</code></a> if the versioned name is not defined) |
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9850 before running any argument. |
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9851 If the variable content has the format <code>@<em>filename</em></code>, |
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9852 then <code>lua</code> executes the file. |
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9853 Otherwise, <code>lua</code> executes the string itself. |
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9854 |
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9855 |
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|
9856 <p> |
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9857 When called with option <code>-E</code>, |
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9858 besides ignoring <code>LUA_INIT</code>, |
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9859 Lua also ignores |
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9860 the values of <code>LUA_PATH</code> and <code>LUA_CPATH</code>, |
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9861 setting the values of |
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9862 <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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9863 with the default paths defined in <code>luaconf.h</code>. |
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9864 |
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9865 |
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9866 <p> |
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9867 All options are handled in order, except <code>-i</code> and <code>-E</code>. |
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9868 For instance, an invocation like |
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|
9869 |
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|
9870 <pre> |
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9871 $ lua -e'a=1' -e 'print(a)' script.lua |
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9872 </pre><p> |
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9873 will first set <code>a</code> to 1, then print the value of <code>a</code>, |
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9874 and finally run the file <code>script.lua</code> with no arguments. |
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9875 (Here <code>$</code> is the shell prompt. Your prompt may be different.) |
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9876 |
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9877 |
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9878 <p> |
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9879 Before running any code, |
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9880 <code>lua</code> collects all command-line arguments |
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9881 in a global table called <code>arg</code>. |
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9882 The script name goes to index 0, |
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9883 the first argument after the script name goes to index 1, |
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9884 and so on. |
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9885 Any arguments before the script name |
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9886 (that is, the interpreter name plus its options) |
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9887 go to negative indices. |
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9888 For instance, in the call |
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|
9889 |
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|
9890 <pre> |
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9891 $ lua -la b.lua t1 t2 |
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9892 </pre><p> |
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|
9893 the table is like this: |
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|
9894 |
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|
9895 <pre> |
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9896 arg = { [-2] = "lua", [-1] = "-la", |
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9897 [0] = "b.lua", |
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9898 [1] = "t1", [2] = "t2" } |
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9899 </pre><p> |
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9900 If there is no script in the call, |
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9901 the interpreter name goes to index 0, |
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9902 followed by the other arguments. |
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9903 For instance, the call |
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|
9904 |
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|
9905 <pre> |
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9906 $ lua -e "print(arg[1])" |
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9907 </pre><p> |
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9908 will print "<code>-e</code>". |
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9909 If there is a script, |
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9910 the script is called with parameters |
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9911 <code>arg[1]</code>, ···, <code>arg[#arg]</code>. |
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9912 (Like all chunks in Lua, |
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9913 the script is compiled as a vararg function.) |
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9914 |
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9915 |
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9916 <p> |
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9917 In interactive mode, |
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9918 Lua repeatedly prompts and waits for a line. |
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9919 After reading a line, |
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9920 Lua first try to interpret the line as an expression. |
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9921 If it succeeds, it prints its value. |
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9922 Otherwise, it interprets the line as a statement. |
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9923 If you write an incomplete statement, |
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9924 the interpreter waits for its completion |
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9925 by issuing a different prompt. |
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9926 |
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9927 |
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9928 <p> |
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9929 In case of unprotected errors in the script, |
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9930 the interpreter reports the error to the standard error stream. |
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9931 If the error object is not a string but |
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9932 has a metamethod <code>__tostring</code>, |
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9933 the interpreter calls this metamethod to produce the final message. |
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9934 Otherwise, the interpreter converts the error object to a string |
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9935 and adds a stack traceback to it. |
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9936 |
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9937 |
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9938 <p> |
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|
9939 When finishing normally, |
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|
9940 the interpreter closes its main Lua state |
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|
9941 (see <a href="#lua_close"><code>lua_close</code></a>). |
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|
9942 The script can avoid this step by |
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|
9943 calling <a href="#pdf-os.exit"><code>os.exit</code></a> to terminate. |
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|
9944 |
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|
9945 |
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diff
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|
9946 <p> |
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|
9947 To allow the use of Lua as a |
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|
9948 script interpreter in Unix systems, |
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9949 the standalone interpreter skips |
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9950 the first line of a chunk if it starts with <code>#</code>. |
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|
9951 Therefore, Lua scripts can be made into executable programs |
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|
9952 by using <code>chmod +x</code> and the <code>#!</code> form, |
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9953 as in |
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|
9954 |
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diff
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|
9955 <pre> |
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|
9956 #!/usr/local/bin/lua |
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|
9957 </pre><p> |
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|
9958 (Of course, |
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|
9959 the location of the Lua interpreter may be different in your machine. |
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|
9960 If <code>lua</code> is in your <code>PATH</code>, |
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|
9961 then |
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|
9962 |
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|
9963 <pre> |
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|
9964 #!/usr/bin/env lua |
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|
9965 </pre><p> |
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|
9966 is a more portable solution.) |
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|
9967 |
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|
9968 |
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|
9969 |
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|
9970 <h1>8 – <a name="8">Incompatibilities with the Previous Version</a></h1> |
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9971 |
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|
9972 <p> |
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|
9973 Here we list the incompatibilities that you may find when moving a program |
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9974 from Lua 5.2 to Lua 5.3. |
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|
9975 You can avoid some incompatibilities by compiling Lua with |
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|
9976 appropriate options (see file <code>luaconf.h</code>). |
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9977 However, |
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|
9978 all these compatibility options will be removed in the future. |
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|
9979 |
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|
9980 |
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|
9981 <p> |
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|
9982 Lua versions can always change the C API in ways that |
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|
9983 do not imply source-code changes in a program, |
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9984 such as the numeric values for constants |
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|
9985 or the implementation of functions as macros. |
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9986 Therefore, |
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|
9987 you should not assume that binaries are compatible between |
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9988 different Lua versions. |
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|
9989 Always recompile clients of the Lua API when |
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9990 using a new version. |
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|
9991 |
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|
9992 |
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|
9993 <p> |
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|
9994 Similarly, Lua versions can always change the internal representation |
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9995 of precompiled chunks; |
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|
9996 precompiled chunks are not compatible between different Lua versions. |
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|
9997 |
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|
9998 |
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|
9999 <p> |
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|
10000 The standard paths in the official distribution may |
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10001 change between versions. |
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|
10002 |
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|
10003 |
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|
10004 |
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|
10005 <h2>8.1 – <a name="8.1">Changes in the Language</a></h2> |
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10006 <ul> |
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|
10007 |
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10008 <li> |
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10009 The main difference between Lua 5.2 and Lua 5.3 is the |
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10010 introduction of an integer subtype for numbers. |
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|
10011 Although this change should not affect "normal" computations, |
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10012 some computations |
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|
10013 (mainly those that involve some kind of overflow) |
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10014 can give different results. |
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|
10015 |
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|
10016 |
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|
10017 <p> |
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|
10018 You can fix these differences by forcing a number to be a float |
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|
10019 (in Lua 5.2 all numbers were float), |
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10020 in particular writing constants with an ending <code>.0</code> |
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|
10021 or using <code>x = x + 0.0</code> to convert a variable. |
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10022 (This recommendation is only for a quick fix |
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|
10023 for an occasional incompatibility; |
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|
10024 it is not a general guideline for good programming. |
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|
10025 For good programming, |
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|
10026 use floats where you need floats |
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|
10027 and integers where you need integers.) |
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|
10028 </li> |
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|
10029 |
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|
10030 <li> |
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|
10031 The conversion of a float to a string now adds a <code>.0</code> suffix |
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10032 to the result if it looks like an integer. |
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|
10033 (For instance, the float 2.0 will be printed as <code>2.0</code>, |
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|
10034 not as <code>2</code>.) |
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|
10035 You should always use an explicit format |
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|
10036 when you need a specific format for numbers. |
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|
10037 |
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|
10038 |
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|
10039 <p> |
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|
10040 (Formally this is not an incompatibility, |
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|
10041 because Lua does not specify how numbers are formatted as strings, |
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|
10042 but some programs assumed a specific format.) |
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|
10043 </li> |
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|
10044 |
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|
10045 <li> |
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|
10046 The generational mode for the garbage collector was removed. |
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|
10047 (It was an experimental feature in Lua 5.2.) |
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|
10048 </li> |
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|
10049 |
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|
10050 </ul> |
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|
10051 |
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|
10052 |
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|
10053 |
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|
10054 |
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|
10055 <h2>8.2 – <a name="8.2">Changes in the Libraries</a></h2> |
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|
10056 <ul> |
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|
10057 |
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|
10058 <li> |
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|
10059 The <code>bit32</code> library has been deprecated. |
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|
10060 It is easy to require a compatible external library or, |
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|
10061 better yet, to replace its functions with appropriate bitwise operations. |
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|
10062 (Keep in mind that <code>bit32</code> operates on 32-bit integers, |
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|
10063 while the bitwise operators in standard Lua operate on 64-bit integers.) |
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10064 </li> |
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10065 |
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10066 <li> |
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10067 The Table library now respects metamethods |
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10068 for setting and getting elements. |
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10069 </li> |
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10070 |
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10071 <li> |
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10072 The <a href="#pdf-ipairs"><code>ipairs</code></a> iterator now respects metamethods and |
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10073 its <code>__ipairs</code> metamethod has been deprecated. |
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10074 </li> |
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10075 |
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10076 <li> |
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10077 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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10078 For compatibility, Lua will continue to ignore this character. |
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10079 </li> |
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10080 |
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10081 <li> |
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10082 The following functions were deprecated in the mathematical library: |
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10083 <code>atan2</code>, <code>cosh</code>, <code>sinh</code>, <code>tanh</code>, <code>pow</code>, |
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10084 <code>frexp</code>, and <code>ldexp</code>. |
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10085 You can replace <code>math.pow(x,y)</code> with <code>x^y</code>; |
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10086 you can replace <code>math.atan2</code> with <code>math.atan</code>, |
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10087 which now accepts one or two parameters; |
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10088 you can replace <code>math.ldexp(x,exp)</code> with <code>x * 2.0^exp</code>. |
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10089 For the other operations, |
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10090 you can either use an external library or |
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10091 implement them in Lua. |
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10092 </li> |
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10093 |
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10094 <li> |
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10095 The searcher for C loaders used by <a href="#pdf-require"><code>require</code></a> |
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10096 changed the way it handles versioned names. |
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10097 Now, the version should come after the module name |
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10098 (as is usual in most other tools). |
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10099 For compatibility, that searcher still tries the old format |
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10100 if it cannot find an open function according to the new style. |
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10101 (Lua 5.2 already worked that way, |
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10102 but it did not document the change.) |
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10103 </li> |
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10104 |
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10105 </ul> |
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10106 |
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10107 |
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10108 |
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10109 |
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10110 <h2>8.3 – <a name="8.3">Changes in the API</a></h2> |
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10111 |
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10112 |
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10113 <ul> |
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10114 |
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10115 <li> |
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10116 Continuation functions now receive as parameters what they needed |
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10117 to get through <code>lua_getctx</code>, |
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10118 so <code>lua_getctx</code> has been removed. |
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10119 Adapt your code accordingly. |
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10120 </li> |
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10121 |
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10122 <li> |
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10123 Function <a href="#lua_dump"><code>lua_dump</code></a> has an extra parameter, <code>strip</code>. |
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10124 Use 0 as the value of this parameter to get the old behavior. |
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10125 </li> |
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10126 |
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10127 <li> |
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10128 Functions to inject/project unsigned integers |
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10129 (<code>lua_pushunsigned</code>, <code>lua_tounsigned</code>, <code>lua_tounsignedx</code>, |
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10130 <code>luaL_checkunsigned</code>, <code>luaL_optunsigned</code>) |
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10131 were deprecated. |
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10132 Use their signed equivalents with a type cast. |
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10133 </li> |
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10134 |
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10135 <li> |
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10136 Macros to project non-default integer types |
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10137 (<code>luaL_checkint</code>, <code>luaL_optint</code>, <code>luaL_checklong</code>, <code>luaL_optlong</code>) |
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10138 were deprecated. |
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10139 Use their equivalent over <a href="#lua_Integer"><code>lua_Integer</code></a> with a type cast |
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10140 (or, when possible, use <a href="#lua_Integer"><code>lua_Integer</code></a> in your code). |
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10141 </li> |
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10142 |
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10143 </ul> |
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10144 |
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10145 |
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10146 |
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10147 |
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10148 <h1>9 – <a name="9">The Complete Syntax of Lua</a></h1> |
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10149 |
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10150 <p> |
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10151 Here is the complete syntax of Lua in extended BNF. |
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10152 As usual in extended BNF, |
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10153 {A} means 0 or more As, |
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10154 and [A] means an optional A. |
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10155 (For operator precedences, see <a href="#3.4.8">§3.4.8</a>; |
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10156 for a description of the terminals |
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10157 Name, Numeral, |
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10158 and LiteralString, see <a href="#3.1">§3.1</a>.) |
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10159 |
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10160 |
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10161 |
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10162 |
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10163 <pre> |
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10164 |
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10165 chunk ::= block |
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10166 |
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10167 block ::= {stat} [retstat] |
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10168 |
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10169 stat ::= ‘<b>;</b>’ | |
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10170 varlist ‘<b>=</b>’ explist | |
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10171 functioncall | |
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10172 label | |
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10173 <b>break</b> | |
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10174 <b>goto</b> Name | |
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10175 <b>do</b> block <b>end</b> | |
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10176 <b>while</b> exp <b>do</b> block <b>end</b> | |
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10177 <b>repeat</b> block <b>until</b> exp | |
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10178 <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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10179 <b>for</b> Name ‘<b>=</b>’ exp ‘<b>,</b>’ exp [‘<b>,</b>’ exp] <b>do</b> block <b>end</b> | |
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10180 <b>for</b> namelist <b>in</b> explist <b>do</b> block <b>end</b> | |
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10181 <b>function</b> funcname funcbody | |
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10182 <b>local</b> <b>function</b> Name funcbody | |
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10183 <b>local</b> namelist [‘<b>=</b>’ explist] |
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10184 |
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10185 retstat ::= <b>return</b> [explist] [‘<b>;</b>’] |
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10186 |
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10187 label ::= ‘<b>::</b>’ Name ‘<b>::</b>’ |
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10188 |
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10189 funcname ::= Name {‘<b>.</b>’ Name} [‘<b>:</b>’ Name] |
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10190 |
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10191 varlist ::= var {‘<b>,</b>’ var} |
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10192 |
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10193 var ::= Name | prefixexp ‘<b>[</b>’ exp ‘<b>]</b>’ | prefixexp ‘<b>.</b>’ Name |
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10194 |
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10195 namelist ::= Name {‘<b>,</b>’ Name} |
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10196 |
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10197 explist ::= exp {‘<b>,</b>’ exp} |
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10198 |
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10199 exp ::= <b>nil</b> | <b>false</b> | <b>true</b> | Numeral | LiteralString | ‘<b>...</b>’ | functiondef | |
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10200 prefixexp | tableconstructor | exp binop exp | unop exp |
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10201 |
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10202 prefixexp ::= var | functioncall | ‘<b>(</b>’ exp ‘<b>)</b>’ |
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10203 |
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10204 functioncall ::= prefixexp args | prefixexp ‘<b>:</b>’ Name args |
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10205 |
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10206 args ::= ‘<b>(</b>’ [explist] ‘<b>)</b>’ | tableconstructor | LiteralString |
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10207 |
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10208 functiondef ::= <b>function</b> funcbody |
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10209 |
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10210 funcbody ::= ‘<b>(</b>’ [parlist] ‘<b>)</b>’ block <b>end</b> |
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10211 |
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10212 parlist ::= namelist [‘<b>,</b>’ ‘<b>...</b>’] | ‘<b>...</b>’ |
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10213 |
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10214 tableconstructor ::= ‘<b>{</b>’ [fieldlist] ‘<b>}</b>’ |
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10215 |
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10216 fieldlist ::= field {fieldsep field} [fieldsep] |
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10217 |
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10218 field ::= ‘<b>[</b>’ exp ‘<b>]</b>’ ‘<b>=</b>’ exp | Name ‘<b>=</b>’ exp | exp |
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10219 |
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10220 fieldsep ::= ‘<b>,</b>’ | ‘<b>;</b>’ |
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10221 |
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10222 binop ::= ‘<b>+</b>’ | ‘<b>-</b>’ | ‘<b>*</b>’ | ‘<b>/</b>’ | ‘<b>//</b>’ | ‘<b>^</b>’ | ‘<b>%</b>’ | |
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10223 ‘<b>&</b>’ | ‘<b>~</b>’ | ‘<b>|</b>’ | ‘<b>>></b>’ | ‘<b><<</b>’ | ‘<b>..</b>’ | |
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10224 ‘<b><</b>’ | ‘<b><=</b>’ | ‘<b>></b>’ | ‘<b>>=</b>’ | ‘<b>==</b>’ | ‘<b>~=</b>’ | |
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10225 <b>and</b> | <b>or</b> |
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10226 |
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10227 unop ::= ‘<b>-</b>’ | <b>not</b> | ‘<b>#</b>’ | ‘<b>~</b>’ |
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10228 |
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10229 </pre> |
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10230 |
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10231 <p> |
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10232 |
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10233 |
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10234 |
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10235 |
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10236 |
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10237 |
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10238 |
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10239 |
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10240 <HR> |
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10241 <SMALL CLASS="footer"> |
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10242 Last update: |
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10243 Fri Jan 16 00:58:20 BRST 2015 |
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10244 </SMALL> |
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10245 <!-- |
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10246 Last change: minor edit |
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10247 --> |
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10248 |
372 | 10249 </div> |
10250 </body> | |
10251 </html> |