Mercurial Hosting > luan
annotate website/src/manual.html.luan @ 675:d95caff8ba8c
minor
author | Franklin Schmidt <fschmidt@gmail.com> |
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date | Tue, 12 Apr 2016 19:41:26 -0600 |
parents | c4216a583de4 |
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478 | 1 local Luan = require "luan:Luan" |
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2 local Io = require "luan:Io" |
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3 local Html = require "luan:Html" |
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4 local Http = require "luan:http/Http" |
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5 local Shared = require "site:/Shared" |
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6 |
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7 |
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8 return function() |
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9 Io.stdout = Http.response.text_writer() |
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10 %> |
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11 <html> |
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12 <head> |
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13 <title>Luan Reference Manual</title> |
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14 <style> |
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15 @import "/site.css"; |
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16 </style> |
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17 </head> |
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18 <body> |
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19 |
372 | 20 <div container> |
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21 <% Shared.header() %> |
372 | 22 |
23 <h1>Luan Reference Manual</h1> | |
24 | |
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25 <p small> |
372 | 26 Original copyright © 2015 Lua.org, PUC-Rio. |
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27 Freely available under the terms of the |
372 | 28 <a href="http://www.lua.org/license.html">Lua license</a>. |
29 Modified for Luan. | |
30 </p> | |
31 | |
32 <hr/> | |
33 | |
34 <h2>Contents</h2> | |
35 | |
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36 <div contents><a href="#intro">Introduction</a></div> |
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37 |
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38 <div contents> |
373 | 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 | |
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49 <div contents> |
380 | 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> | |
389 | 54 <li> |
55 <a href="#stmts">Statements</a> | |
56 <ul> | |
57 <li><a href="#blocks">Blocks</a></li> | |
395 | 58 <li><a href="#chunks">Chunks</a></li> |
59 <li><a href="#assignment">Assignment</a></li> | |
60 <li><a href="#control">Control Structures</a></li> | |
61 <li><a href="#for">For Statement</a></li> | |
62 <li><a href="#fn_stmt">Function Calls as Statements</a></li> | |
63 <li><a href="#local_stmt">Local Declarations</a></li> | |
465 | 64 <li><a href="#template_stmt">Template Statements</a></li> |
395 | 65 </ul> |
66 </li> | |
67 <li> | |
68 <a href="#expressions">Expressions</a> | |
69 <ul> | |
70 <li><a href="#arithmetic">Arithmetic Operators</a></li> | |
396 | 71 <li><a href="#conversions">Coercions and Conversions</a></li> |
72 <li><a href="#relational">Relational Operators</a></li> | |
73 <li><a href="#logical_ops">Logical Operators</a></li> | |
74 <li><a href="#concatenation">Concatenation</a></li> | |
75 <li><a href="#length">The Length Operator</a></li> | |
76 <li><a href="#precedence">Precedence</a></li> | |
77 <li><a href="#constructors">Table Constructors</a></li> | |
417 | 78 <li><a href="#fn_calls">Function Calls</a></li> |
79 <li><a href="#fn_def">Function Definitions</a></li> | |
465 | 80 <li><a href="#template_expr">Template Expressions</a></li> |
389 | 81 </ul> |
82 </li> | |
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83 <li><a href="#visibility">Visibility Rules</a></li> |
373 | 84 </ul> |
85 </div> | |
86 | |
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87 <div contents> |
468 | 88 <a href="#libs">Standard Libraries</a> |
89 <ul> | |
90 <li><a href="#default_lib">Default Environment</a></li> | |
470 | 91 <li><a href="#luan_lib">Basic Functions</a></li> |
476 | 92 <li><a href="#package_lib">Modules</a></li> |
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93 <li><a href="#string_lib">String Manipulation</a></li> |
567 | 94 <li><a href="#binary_lib">Binary Manipulation</a></li> |
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95 <li><a href="#table_lib">Table Manipulation</a></li> |
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96 <li><a href="#number_lib">Number Manipulation</a></li> |
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97 <li><a href="#math_lib">Mathematical Functions</a></li> |
468 | 98 </ul> |
99 </div> | |
100 | |
372 | 101 <hr/> |
102 | |
373 | 103 |
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104 <h2 heading><a name="intro">Introduction</a></h2> |
372 | 105 |
106 <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> | |
107 | |
108 <p>Luan is implemented in Java and is tightly coupled with Java. So it makes a great scripting language for Java programmers.</p> | |
109 | |
110 <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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111 |
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112 |
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113 <h2 heading><a name="basic">Basic Concepts</a></h2> |
373 | 114 |
115 <p>This section describes the basic concepts of the language.</p> | |
116 | |
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117 <h3 heading><a name="types">Values and Types</a></h3> |
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118 |
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119 <p> |
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120 Luan is a <em>dynamically typed language</em>. |
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121 This means that |
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122 variables do not have types; only values do. |
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123 There are no type definitions in the language. |
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124 All values carry their own type. |
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125 |
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126 |
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127 <p> |
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128 All values in Luan are <em>first-class values</em>. |
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129 This means that all values can be stored in variables, |
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130 passed as arguments to other functions, and returned as results. |
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131 |
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132 |
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133 <p> |
373 | 134 There are eight basic types in Luan: |
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135 <em>nil</em>, <em>boolean</em>, <em>number</em>, |
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136 <em>string</em>, <em>binary</em>, <em>function</em>, <em>java</em>, |
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137 and <em>table</em>. |
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138 <em>Nil</em> is the type of the value <b>nil</b>, |
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139 whose main property is to be different from any other value; |
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140 it usually represents the absence of a useful value. |
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141 <em>Nil</em> is implemented as the Java value <em>null</em>. |
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142 <em>Boolean</em> is the type of the values <b>false</b> and <b>true</b>. |
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143 <em>Boolean</em> is implemented as the Java class <em>Boolean</em>. |
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144 <em>Number</em> represents both |
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145 integer numbers and real (floating-point) numbers. |
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146 <em>Number</em> is implemented as the Java class <em>Number</em>. Any Java subclass of <em>Number</em> is allowed and this is invisible to the Luan user. Operations on numbers follow the same rules of |
373 | 147 the underlying Java implementation. |
148 | |
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149 <em>String</em> is implemented as the Java class <em>String</em>. |
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150 <em>Binary</em> is implemented as the Java type <em>byte[]</em>. |
373 | 151 |
152 | |
153 <p> | |
154 Luan can call (and manipulate) functions written in Luan and | |
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155 functions written in Java (see <a href="#fn_calls">Function Calls</a>). |
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156 Both are represented by the type <em>function</em>. |
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157 |
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158 |
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159 <p> |
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160 The type <em>java</em> is provided to allow arbitrary Java objects to |
373 | 161 be stored in Luan variables. |
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162 A <em>java</em> value is a Java object that isn't one of the standard Luan types. |
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163 Java values have no predefined operations in Luan, |
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164 except assignment and identity test. |
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165 Java values are useful when Java access is enabled in Luan |
373 | 166 |
167 | |
168 | |
169 <p> | |
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170 The type <em>table</em> implements associative arrays, |
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171 that is, arrays that can be indexed not only with numbers, |
373 | 172 but with any Luan value except <b>nil</b>. |
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173 Tables can be <em>heterogeneous</em>; |
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174 that is, they can contain values of all types (except <b>nil</b>). |
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175 Any key with value <b>nil</b> is not considered part of the table. |
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176 Conversely, any key that is not part of a table has |
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177 an associated value <b>nil</b>. |
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178 |
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179 |
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180 <p> |
373 | 181 Tables are the sole data-structuring mechanism in Luan; |
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182 they can be used to represent ordinary arrays, sequences, |
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183 symbol tables, sets, records, graphs, trees, etc. |
373 | 184 To represent records, Luan uses the field name as an index. |
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185 The language supports this representation by |
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186 providing <code>a.name</code> as syntactic sugar for <code>a["name"]</code>. |
373 | 187 There are several convenient ways to create tables in Luan |
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188 (see <a href="#constructors">Table Constructors</a>). |
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189 |
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190 |
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191 <p> |
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192 We use the term <em>sequence</em> to denote a table where |
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193 the set of all positive numeric keys is equal to {1..<em>n</em>} |
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194 for some non-negative integer <em>n</em>, |
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195 which is called the length of the sequence (see <a href="#length">The Length Operator</a>). |
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196 |
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197 |
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198 <p> |
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199 Like indices, |
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200 the values of table fields can be of any type. |
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201 In particular, |
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202 because functions are first-class values, |
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203 table fields can contain functions. |
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204 Thus tables can also carry <em>methods</em> (see <a href="#fn_def">Function Definitions</a>). |
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205 |
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206 |
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207 <p> |
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208 The indexing of tables follows |
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209 the definition of raw equality in the language. |
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210 The expressions <code>a[i]</code> and <code>a[j]</code> |
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211 denote the same table element |
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212 if and only if <code>i</code> and <code>j</code> are raw equal |
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213 (that is, equal without metamethods). |
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214 In particular, floats with integral values |
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215 are equal to their respective integers |
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216 (e.g., <code>1.0 == 1</code>). |
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217 |
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218 |
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219 <p> |
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220 Luan values are <em>objects</em>: |
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221 variables do not actually <em>contain</em> values, |
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222 only <em>references</em> to them. |
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223 Assignment, parameter passing, and function returns |
373 | 224 always manipulate references to values; |
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225 these operations do not imply any kind of copy. |
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226 |
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227 |
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228 <p> |
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229 The library function <a href="#Luan.type"><code>Luan.type</code></a> returns a string describing the type |
478 | 230 of a given value. |
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231 |
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232 |
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233 |
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234 |
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235 |
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236 <h3 heading><a name="env">Environments</a></h3> |
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237 |
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238 <p> |
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239 The environment of a chunk starts with only two local variables: <code><a href="#require">require</a></code> and <code><a href="#java">java</a></code>. These are functions are used to load and access libraries and other modules. All other variables must be added to the environment using <a href="http://localhost:8080/manual.html#local_stmt">local declarations</a>. |
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240 |
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241 <p> |
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242 As will be discussed in <a href="#vars">Variables</a> and <a href=#assignment">Assignment</a>, |
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243 any reference to a free name |
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244 (that is, a name not bound to any declaration) <code>var</code> |
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245 can be syntactically translated to <code>_ENV.var</code> if <code>_ENV</code> is defined. |
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246 |
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247 |
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248 <h3 heading><a name="error">Error Handling</a></h3> |
373 | 249 |
250 <p> | |
251 Luan code can explicitly generate an error by calling the | |
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252 <a href="#Luan.error"><code>error</code></a> function. |
373 | 253 If you need to catch errors in Luan, |
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254 you can use <a href="#Luan.pcall"><code>pcall</code></a> or <a href="#Luan.try"><code>try</code></a> |
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255 to call a given function in <em>protected mode</em>. |
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256 |
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257 |
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258 <p> |
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259 Whenever there is an error, |
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260 an <em>error table</em> |
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261 is propagated with information about the error. |
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262 See <a href="#Luan.new_error"><code>Luan.new_error</code></a>. |
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263 |
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264 |
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265 |
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266 <h3 heading><a name="meta">Metatables and Metamethods</a></h3> |
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267 |
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268 <p> |
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269 Every table in Luan can have a <em>metatable</em>. |
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270 This <em>metatable</em> is an ordinary Luan table |
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271 that defines the behavior of the original value |
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272 under certain special operations. |
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273 You can change several aspects of the behavior |
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274 of operations over a value by setting specific fields in its metatable. |
373 | 275 For instance, when a table is the operand of an addition, |
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276 Luan checks for a function in the field "<code>__add</code>" of the table's metatable. |
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277 If it finds one, |
373 | 278 Luan calls this function to perform the addition. |
279 | |
280 | |
281 <p> | |
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282 The keys in a metatable are derived from the <em>event</em> names; |
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283 the corresponding values are called <ii>metamethods</em>. |
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284 In the previous example, the event is <code>"add"</code> |
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285 and the metamethod is the function that performs the addition. |
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286 |
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287 |
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288 <p> |
373 | 289 You can query the metatable of any table |
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290 using the <a href="#Luan.get_metatable"><code>get_metatable</code></a> function. |
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291 |
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292 |
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293 <p> |
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294 You can replace the metatable of tables |
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295 using the <a href="#Luan.set_metatable"><code>set_metatable</code></a> function. |
373 | 296 |
297 | |
298 <p> | |
299 A metatable controls how a table behaves in | |
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300 arithmetic operations, bitwise operations, |
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301 order comparisons, concatenation, length operation, calls, and indexing. |
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302 |
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303 |
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304 <p> |
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305 A detailed list of events controlled by metatables is given next. |
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306 Each operation is identified by its corresponding event name. |
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307 The key for each event is a string with its name prefixed by |
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308 two underscores, '<code>__</code>'; |
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309 for instance, the key for operation "add" is the |
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310 string "<code>__add</code>". |
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311 Note that queries for metamethods are always raw; |
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312 the access to a metamethod does not invoke other metamethods. |
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313 You can emulate how Luan queries a metamethod for an object <code>obj</code> |
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314 with the following code: |
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315 |
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316 <pre> |
373 | 317 raw_get(get_metatable(obj) or {}, "__" .. event_name) |
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318 </pre> |
373 | 319 |
320 <p> | |
321 Here are the events: | |
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322 |
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323 <ul> |
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324 |
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325 <li><p><b>"add": </b> |
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326 the <code>+</code> operation. |
373 | 327 |
328 If any operand for an addition is a table, | |
329 Luan will try to call a metamethod. | |
330 First, Luan will check the first operand (even if it is valid). | |
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331 If that operand does not define a metamethod for the "<code>__add</code>" event, |
373 | 332 then Luan will check the second operand. |
333 If Luan can find a metamethod, | |
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334 it calls the metamethod with the two operands as arguments, |
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335 and the result of the call |
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336 (adjusted to one value) |
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337 is the result of the operation. |
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338 Otherwise, |
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339 it raises an error. |
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340 </li> |
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341 |
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342 <li><p><b>"sub": </b> |
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343 the <code>-</code> operation. |
371
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344 |
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345 Behavior similar to the "add" operation. |
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346 </li> |
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347 |
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348 <li><p><b>"mul": </b> |
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349 the <code>*</code> operation. |
371
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350 |
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351 Behavior similar to the "add" operation. |
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352 </li> |
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353 |
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354 <li><p><b>"div": </b> |
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355 the <code>/</code> operation. |
371
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356 |
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357 Behavior similar to the "add" operation. |
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358 </li> |
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359 |
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360 <li><p><b>"mod": </b> |
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361 the <code>%</code> operation. |
371
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362 |
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363 Behavior similar to the "add" operation. |
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364 </li> |
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365 |
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366 <li><p><b>"pow": </b> |
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367 the <code>^</code> (exponentiation) operation. |
371
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368 |
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369 Behavior similar to the "add" operation. |
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370 </li> |
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371 |
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372 <li><p><b>"unm": </b> |
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373 the <code>-</code> (unary minus) operation. |
371
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374 |
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375 Behavior similar to the "add" operation. |
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376 </li> |
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377 |
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378 <li><p><b>"concat": </b> |
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379 the <code>..</code> (concatenation) operation. |
373 | 380 |
381 Behavior similar to the "add" operation. | |
371
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382 </li> |
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383 |
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384 <li><p><b>"len": </b> |
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385 the <code>#</code> (length) operation. |
373 | 386 |
371
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387 If there is a metamethod, |
373 | 388 Luan calls it with the object as argument, |
371
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389 and the result of the call |
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390 (always adjusted to one value) |
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391 is the result of the operation. |
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392 If there is no metamethod but the object is a table, |
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393 then Luan uses the table length operation (see <a href="#length">The Length Operator</a>). |
373 | 394 Otherwise, Luan raises an error. |
371
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395 </li> |
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396 |
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397 <li><p><b>"eq": </b> |
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398 the <code>==</code> (equal) operation. |
371
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399 |
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400 Behavior similar to the "add" operation, |
373 | 401 except that Luan will try a metamethod only when the values |
402 being compared are both tables | |
371
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403 and they are not primitively equal. |
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404 The result of the call is always converted to a boolean. |
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405 </li> |
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406 |
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407 <li><p><b>"lt": </b> |
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408 the <code><</code> (less than) operation. |
373 | 409 |
410 Behavior similar to the "add" operation. | |
371
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411 The result of the call is always converted to a boolean. |
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412 </li> |
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413 |
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414 <li><p><b>"le": </b> |
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415 the <code><=</code> (less equal) operation. |
371
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416 |
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417 Unlike other operations, |
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418 The less-equal operation can use two different events. |
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419 First, Luan looks for the "<code>__le</code>" metamethod in both operands, |
371
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420 like in the "lt" operation. |
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421 If it cannot find such a metamethod, |
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422 then it will try the "<code>__lt</code>" event, |
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423 assuming that <code>a <= b</code> is equivalent to <code>not (b < a)</code>. |
371
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424 As with the other comparison operators, |
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425 the result is always a boolean. |
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426 </li> |
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427 |
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428 <li><p><b>"index": </b> |
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429 The indexing access <code>table[key]</code>. |
373 | 430 |
431 This event happens | |
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432 when <code>key</code> is not present in <code>table</code>. |
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433 The metamethod is looked up in <code>table</code>. |
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434 |
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435 |
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436 <p> |
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437 Despite the name, |
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438 the metamethod for this event can be any type. |
371
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439 If it is a function, |
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440 it is called with <code>table</code> and <code>key</code> as arguments. |
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441 Otherwise |
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442 the final result is the result of indexing this metamethod object with <code>key</code>. |
371
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443 (This indexing is regular, not raw, |
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444 and therefore can trigger another metamethod if the metamethod object is a table.) |
371
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445 </li> |
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446 |
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447 <li><p><b>"new_index": </b> |
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448 The indexing assignment <code>table[key] = value</code>. |
371
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449 |
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450 Like the index event, |
373 | 451 this event happens when |
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452 when <code>key</code> is not present in <code>table</code>. |
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453 The metamethod is looked up in <code>table</code>. |
371
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454 |
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455 |
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456 <p> |
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457 Like with indexing, |
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458 the metamethod for this event can be either a function or a table. |
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459 If it is a function, |
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460 it is called with <code>table</code>, <code>key</code>, and <code>value</code> as arguments. |
371
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461 If it is a table, |
373 | 462 Luan does an indexing assignment to this table with the same key and value. |
371
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463 (This assignment is regular, not raw, |
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464 and therefore can trigger another metamethod.) |
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465 |
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466 |
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467 <p> |
428
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468 Whenever there is a "new_index" metamethod, |
373 | 469 Luan does not perform the primitive assignment. |
371
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470 (If necessary, |
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471 the metamethod itself can call <a href="#Luan.raw_set"><code>raw_set</code></a> |
371
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472 to do the assignment.) |
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473 </li> |
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474 |
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475 <li><p><b>"call": </b> |
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476 The call operation <code>func(args)</code>. |
373 | 477 |
478 This event happens when Luan tries to call a table. | |
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479 The metamethod is looked up in <code>func</code>. |
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480 If present, |
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481 the metamethod is called with <code>func</code> as its first argument, |
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482 followed by the arguments of the original call (<code>args</code>). |
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483 </li> |
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484 |
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485 </ul> |
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486 |
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487 |
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488 |
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489 |
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490 <h3 heading><a name="gc">Garbage Collection</a></h3> |
380 | 491 |
492 <p> | |
493 Luan uses Java's garbage collection. | |
494 | |
495 | |
496 | |
497 | |
498 | |
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499 <h2 heading><a name="lang">The Language</a></h2> |
380 | 500 |
501 <p> | |
502 This section describes the lexis, the syntax, and the semantics of Luan. | |
371
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503 In other words, |
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504 this section describes |
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505 which tokens are valid, |
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506 how they can be combined, |
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507 and what their combinations mean. |
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508 |
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509 |
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510 <p> |
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511 Language constructs will be explained using the usual extended BNF notation, |
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512 in which |
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513 {<em>a</em>} means 0 or more <em>a</em>'s, and |
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514 [<em>a</em>] means an optional <em>a</em>. |
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515 Non-terminals are shown like non-terminal, |
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516 keywords are shown like <b>kword</b>, |
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517 and other terminal symbols are shown like ‘<b>=</b>’. |
380 | 518 The complete syntax of Luan can be found in <a href="#9">§9</a> |
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519 at the end of this manual. |
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520 |
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521 |
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522 |
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523 <h3 heading><a name="lex">Lexical Conventions</a></h3> |
380 | 524 |
525 <p> | |
526 Luan ignores spaces and comments | |
371
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527 between lexical elements (tokens), |
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528 except as delimiters between names and keywords. |
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529 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 <em>(...)</em> where the end of line is treated as white space. |
562
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530 |
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531 <p> |
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532 <em>Names</em> |
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533 (also called <em>identifiers</em>) |
380 | 534 in Luan can be any string of letters, |
371
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535 digits, and underscores, |
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536 not beginning with a digit. |
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537 Identifiers are used to name variables, table fields, and labels. |
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538 |
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539 |
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540 <p> |
562
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541 The following <em>keywords</em> are reserved |
371
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542 and cannot be used as names: |
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543 |
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544 |
562
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545 <pre> |
371
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546 and break do else elseif end |
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547 false for function goto if in |
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548 local nil not or repeat return |
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549 then true until while |
562
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550 </pre> |
371
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551 |
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552 <p> |
380 | 553 Luan is a case-sensitive language: |
562
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554 <code>and</code> is a reserved word, but <code>And</code> and <code>AND</code> |
371
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555 are two different, valid names. |
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556 |
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557 |
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558 <p> |
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559 The following strings denote other tokens: |
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560 |
562
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561 <pre> |
371
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562 + - * / % ^ # |
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563 & ~ | << >> // |
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564 == ~= <= >= < > = |
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565 ( ) { } [ ] :: |
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566 ; : , . .. ... |
562
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567 </pre> |
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568 |
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569 <p> |
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570 <em>Literal strings</em> |
371
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571 can be delimited by matching single or double quotes, |
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572 and can contain the following C-like escape sequences: |
562
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573 '<code>\a</code>' (bell), |
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574 '<code>\b</code>' (backspace), |
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575 '<code>\f</code>' (form feed), |
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576 '<code>\n</code>' (newline), |
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577 '<code>\r</code>' (carriage return), |
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578 '<code>\t</code>' (horizontal tab), |
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579 '<code>\v</code>' (vertical tab), |
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580 '<code>\\</code>' (backslash), |
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581 '<code>\"</code>' (quotation mark [double quote]), |
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582 and '<code>\'</code>' (apostrophe [single quote]). |
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583 A backslash followed by a real newline |
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584 results in a newline in the string. |
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585 The escape sequence '<code>\z</code>' skips the following span |
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586 of white-space characters, |
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587 including line breaks; |
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588 it is particularly useful to break and indent a long literal string |
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589 into multiple lines without adding the newlines and spaces |
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590 into the string contents. |
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591 |
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592 |
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593 <p> |
380 | 594 Luan can specify any character in a literal string by its numerical value. |
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595 This can be done |
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596 with the escape sequence <code>\x<em>XX</em></code>, |
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597 where <em>XX</em> is a sequence of exactly two hexadecimal digits, |
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598 or with the escape sequence <code>\<em>ddd</em></code>, |
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599 where <em>ddd</em> is a sequence of up to three decimal digits. |
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600 (Note that if a decimal escape sequence is to be followed by a digit, |
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601 it must be expressed using exactly three digits.) |
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602 |
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603 |
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604 <p> |
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605 Literal strings can also be defined using a long format |
562
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606 enclosed by <em>long brackets</em>. |
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607 We define an <em>opening long bracket of level <em>n</em></em> as an opening |
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608 square bracket followed by <em>n</em> equal signs followed by another |
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609 opening square bracket. |
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610 So, an opening long bracket of level 0 is written as <code>[[</code>, |
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611 an opening long bracket of level 1 is written as <code>[=[</code>, |
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612 and so on. |
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613 A <em>closing long bracket</em> is defined similarly; |
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614 for instance, |
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615 a closing long bracket of level 4 is written as <code>]====]</code>. |
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616 A <em>long literal</em> starts with an opening long bracket of any level and |
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617 ends at the first closing long bracket of the same level. |
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618 It can contain any text except a closing bracket of the same level. |
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619 Literals in this bracketed form can run for several lines, |
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620 do not interpret any escape sequences, |
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621 and ignore long brackets of any other level. |
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622 Any kind of end-of-line sequence |
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623 (carriage return, newline, carriage return followed by newline, |
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624 or newline followed by carriage return) |
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625 is converted to a simple newline. |
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626 |
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627 |
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628 <p> |
380 | 629 Any character in a literal string not |
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630 explicitly affected by the previous rules represents itself. |
380 | 631 However, Luan opens files for parsing in text mode, |
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632 and the system file functions may have problems with |
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633 some control characters. |
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634 So, it is safer to represent |
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635 non-text data as a quoted literal with |
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636 explicit escape sequences for non-text characters. |
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637 |
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638 |
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639 <p> |
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640 For convenience, |
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641 when the opening long bracket is immediately followed by a newline, |
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642 the newline is not included in the string. |
380 | 643 As an example |
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644 the five literal strings below denote the same string: |
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645 |
562
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646 <pre> |
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647 a = 'alo\n123"' |
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648 a = "alo\n123\"" |
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649 a = '\97lo\10\04923"' |
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650 a = [[alo |
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651 123"]] |
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652 a = [==[ |
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653 alo |
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654 123"]==] |
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655 </pre> |
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656 |
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657 <p> |
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658 A <em>numerical constant</em> (or <em>numeral</em>) |
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659 can be written with an optional fractional part |
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660 and an optional decimal exponent, |
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661 marked by a letter '<code>e</code>' or '<code>E</code>'. |
380 | 662 Luan also accepts hexadecimal constants, |
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663 which start with <code>0x</code> or <code>0X</code>. |
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664 Hexadecimal constants also accept an optional fractional part |
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665 plus an optional binary exponent, |
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666 marked by a letter '<code>p</code>' or '<code>P</code>'. |
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667 A numeric constant with a fractional dot or an exponent |
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668 denotes a float; |
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669 otherwise it denotes an integer. |
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670 Examples of valid integer constants are |
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671 |
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672 <pre> |
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673 3 345 0xff 0xBEBADA |
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674 </pre> |
382 | 675 |
676 <p> | |
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677 Examples of valid float constants are |
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678 |
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679 <pre> |
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680 3.0 3.1416 314.16e-2 0.31416E1 34e1 |
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681 0x0.1E 0xA23p-4 0X1.921FB54442D18P+1 |
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682 </pre> |
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683 |
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684 <p> |
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685 A <em>comment</em> starts with a double hyphen (<code>--</code>) |
371
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686 anywhere outside a string. |
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687 If the text immediately after <code>--</code> is not an opening long bracket, |
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688 the comment is a <em>short comment</em>, |
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689 which runs until the end of the line. |
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690 Otherwise, it is a <em>long comment</em>, |
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691 which runs until the corresponding closing long bracket. |
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692 Long comments are frequently used to disable code temporarily. |
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693 |
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694 |
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695 |
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696 |
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697 |
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698 <h3 heading><a name="vars">Variables</a></h3> |
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699 |
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700 <p> |
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701 Variables are places that store values. |
380 | 702 There are three kinds of variables in Luan: |
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703 global variables, local variables, and table fields. |
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704 |
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705 <p> |
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706 A single name can denote a global variable or a local variable |
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707 (or a function's formal parameter, |
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708 which is a particular kind of local variable): |
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709 |
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710 <pre> |
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711 var ::= Name |
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712 </pre> |
382 | 713 |
714 <p> | |
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715 Name denotes identifiers, as defined in <a href="#lex">Lexical Conventions</a>. |
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716 |
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717 <p> |
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718 Local variables are <em>lexically scoped</em>: |
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719 local variables can be freely accessed by functions |
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720 defined inside their scope (see <a href="#visibility">Visibility Rules</a>). |
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721 |
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722 |
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723 <p> |
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724 Before the first assignment to a variable, its value is <b>nil</b>. |
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725 |
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726 <p> |
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727 Square brackets are used to index a table: |
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728 |
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729 <pre> |
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730 var ::= prefixexp ‘<b>[</b>’ exp ‘<b>]</b>’ |
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731 </pre> |
382 | 732 |
733 <p> | |
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734 The meaning of accesses to table fields can be changed via metatables. |
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735 An access to an indexed variable <code>t[i]</code> is equivalent to |
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736 a call <code>gettable_event(t,i)</code>. |
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737 (See <a href="#meta">Metatables and Metamethods</a> for a complete description of the |
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738 <code>gettable_event</code> function. |
380 | 739 This function is not defined or callable in Luan. |
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740 We use it here only for explanatory purposes.) |
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741 |
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742 |
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743 <p> |
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744 The syntax <code>var.Name</code> is just syntactic sugar for |
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745 <code>var["Name"]</code>: |
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746 |
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747 <pre> |
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748 var ::= prefixexp ‘<b>.</b>’ Name |
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749 </pre> |
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750 |
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751 <p> |
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752 Global variables are not available by default. To enable global variable, you must define <code>_ENV</code> as a local variable whose value is a table. If <code>_ENV</code> is not defined, then an unrecognized variable name will produce a compile error. If <code>_ENV</code> is defined then an access to an unrecognized variable name will be consider a global variable. So then an acces to global variable <code>x</code> |
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753 is equivalent to <code>_ENV.x</code>. |
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754 Due to the way that chunks are compiled, |
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755 <code>_ENV</code> is never a global name (see <a href="#env">Environments</a>). |
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756 |
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757 |
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758 |
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759 |
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760 |
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761 <h3 heading><a name="stmts">Statements</a></h3> |
389 | 762 |
763 <p> | |
764 Luan supports an almost conventional set of statements, | |
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765 similar to those in Pascal or C. |
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766 This set includes |
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767 assignments, control structures, function calls, |
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768 and variable declarations. |
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769 |
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770 |
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771 |
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772 <h4 heading><a name="blocks">Blocks</a></h4> |
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773 |
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774 <p> |
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775 A block is a list of statements, |
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776 which are executed sequentially: |
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777 |
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778 <pre> |
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779 block ::= {stat} |
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780 </pre> |
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781 |
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782 <p> |
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783 Luan has <em>empty statements</em> |
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784 that allow you to separate statements with semicolons, |
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785 start a block with a semicolon |
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786 or write two semicolons in sequence: |
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787 |
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788 <pre> |
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789 stat ::= ‘<b>;</b>’ |
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790 </pre> |
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791 |
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792 <p> |
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793 A block can be explicitly delimited to produce a single statement: |
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794 |
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795 <pre> |
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796 stat ::= <b>do</b> block <b>end</b> |
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797 </pre> |
389 | 798 |
799 <p> | |
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800 Explicit blocks are useful |
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801 to control the scope of variable declarations. |
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802 Explicit blocks are also sometimes used to |
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803 add a <b>return</b> statement in the middle |
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804 of another block (see <a href="#control">Control Structures</a>). |
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805 |
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806 |
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807 |
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808 |
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809 |
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810 <h4 heading><a name="chunks">Chunks</a></h4> |
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811 |
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812 <p> |
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813 The unit of compilation of Luan is called a <em>chunk</em>. |
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814 Syntactically, |
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815 a chunk is simply a block: |
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816 |
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817 <pre> |
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818 chunk ::= block |
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819 </pre> |
395 | 820 |
821 <p> | |
822 Luan handles a chunk as the body of an anonymous function | |
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823 with a variable number of arguments |
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824 (see <a href="#fn_def">Function Definitions</a>). |
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825 As such, chunks can define local variables, |
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826 receive arguments, and return values. |
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827 |
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828 |
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829 <p> |
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830 A chunk can be stored in a file or in a string inside the host program. |
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831 To execute a chunk, |
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832 Luan first <em>loads</em> it, |
395 | 833 compiling the chunk's code, |
834 and then Luan executes the compiled code. | |
835 | |
836 | |
837 | |
838 | |
839 | |
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840 <h4 heading><a name="assignment">Assignment</a></h4> |
395 | 841 |
842 <p> | |
843 Luan allows multiple assignments. | |
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844 Therefore, the syntax for assignment |
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845 defines a list of variables on the left side |
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846 and a list of expressions on the right side. |
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847 The elements in both lists are separated by commas: |
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848 |
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849 <pre> |
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850 stat ::= varlist ‘<b>=</b>’ explist |
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851 varlist ::= var {‘<b>,</b>’ var} |
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852 explist ::= exp {‘<b>,</b>’ exp} |
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853 </pre> |
395 | 854 |
855 <p> | |
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856 Expressions are discussed in <a href="#expressions">Expressions</a>. |
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857 |
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858 |
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859 <p> |
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860 Before the assignment, |
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861 the list of values is <em>adjusted</em> to the length of |
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862 the list of variables. |
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863 If there are more values than needed, |
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864 the excess values are thrown away. |
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865 If there are fewer values than needed, |
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866 the list is extended with as many <b>nil</b>'s as needed. |
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867 If the list of expressions ends with a function call, |
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868 then all values returned by that call enter the list of values, |
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869 before the adjustment |
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870 (except when the call is enclosed in parentheses; see <a href="#expressions">Expressions</a>). |
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871 |
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872 |
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873 <p> |
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874 The assignment statement first evaluates all its expressions |
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875 and only then the assignments are performed. |
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876 Thus the code |
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877 |
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878 <pre> |
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879 i = 3 |
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880 i, a[i] = i+1, 20 |
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881 </pre> |
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882 |
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883 <p> |
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884 sets <code>a[3]</code> to 20, without affecting <code>a[4]</code> |
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885 because the <code>i</code> in <code>a[i]</code> is evaluated (to 3) |
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886 before it is assigned 4. |
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887 Similarly, the line |
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888 |
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889 <pre> |
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890 x, y = y, x |
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891 </pre> |
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892 |
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893 <p> |
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894 exchanges the values of <code>x</code> and <code>y</code>, |
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895 and |
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896 |
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897 <pre> |
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898 x, y, z = y, z, x |
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899 </pre> |
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900 |
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901 <p> |
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902 cyclically permutes the values of <code>x</code>, <code>y</code>, and <code>z</code>. |
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903 |
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904 |
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905 <p> |
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906 The meaning of assignments to global variables |
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907 and table fields can be changed via metatables. |
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908 An assignment to an indexed variable <code>t[i] = val</code> is equivalent to |
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909 <code>settable_event(t,i,val)</code>. |
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910 (See <a href="#meta">Metatables and Metamethods</a> for a complete description of the |
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911 <code>settable_event</code> function. |
395 | 912 This function is not defined or callable in Luan. |
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913 We use it here only for explanatory purposes.) |
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914 |
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915 |
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916 <p> |
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917 An assignment to a global name <code>x = val</code> |
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918 is equivalent to the assignment |
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919 <code>_ENV.x = val</code> (see <a href="#env">Environments</a>). |
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920 Global names are only available when <code>_ENV</code> is defined. |
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921 |
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922 |
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923 |
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924 <h4 heading><a name="control">Control Structures</a></h4> |
395 | 925 |
926 <p> | |
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927 The control structures |
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928 <b>if</b>, <b>while</b>, and <b>repeat</b> have the usual meaning and |
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929 familiar syntax: |
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930 |
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931 <pre> |
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932 stat ::= <b>while</b> exp <b>do</b> block <b>end</b> |
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933 stat ::= <b>repeat</b> block <b>until</b> exp |
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934 stat ::= <b>if</b> exp <b>then</b> block {<b>elseif</b> exp <b>then</b> block} [<b>else</b> block] <b>end</b> |
562
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935 </pre> |
395 | 936 |
937 <p> | |
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938 Luan also has a <b>for</b> statement (see <a href="#for">For Statement</a>). |
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939 |
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940 |
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941 <p> |
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942 The condition expression of a |
395 | 943 control structure must be a boolean. |
944 Any other value type will produce an error. | |
945 This helps catch errors and makes code more readable. | |
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946 |
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947 |
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948 <p> |
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949 In the <b>repeat</b>–<b>until</b> loop, |
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950 the inner block does not end at the <b>until</b> keyword, |
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951 but only after the condition. |
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952 So, the condition can refer to local variables |
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953 declared inside the loop block. |
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954 |
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955 |
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956 <p> |
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957 The <b>break</b> statement terminates the execution of a |
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958 <b>while</b>, <b>repeat</b>, or <b>for</b> loop, |
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959 skipping to the next statement after the loop: |
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960 |
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961 |
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962 <pre> |
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963 stat ::= <b>break</b> |
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964 </pre> |
395 | 965 |
966 <p> | |
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967 A <b>break</b> ends the innermost enclosing loop. |
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968 |
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969 |
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970 <p> |
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971 The <b>return</b> statement is used to return values |
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972 from a function or a chunk |
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973 (which is an anonymous function). |
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974 |
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975 Functions can return more than one value, |
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976 so the syntax for the <b>return</b> statement is |
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977 |
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978 <pre> |
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979 stat ::= <b>return</b> [explist] [‘<b>;</b>’] |
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980 </pre> |
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981 |
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982 |
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983 |
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984 |
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985 <h4 heading><a name="for">For Statement</a></h4> |
395 | 986 |
987 <p> | |
988 The <b>for</b> statement works over functions, | |
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989 called <em>iterators</em>. |
395 | 990 On each iteration, the iterator function is called to produce a new value, |
991 stopping when this new value is <b>nil</b>. | |
992 The <b>for</b> loop has the following syntax: | |
993 | |
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994 <pre> |
395 | 995 stat ::= <b>for</b> namelist <b>in</b> exp <b>do</b> block <b>end</b> |
996 namelist ::= Name {‘<b>,</b>’ Name} | |
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997 </pre> |
395 | 998 |
999 <p> | |
1000 A <b>for</b> statement like | |
1001 | |
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1002 <pre> |
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1003 for <em>var_1</em>, ···, <em>var_n</em> in <em>exp</em> do <em>block</em> end |
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1004 </pre> |
395 | 1005 |
1006 <p> | |
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1007 is equivalent to the code: |
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1008 |
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1009 <pre> |
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1010 do |
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1011 local <em>f</em> = <em>exp</em> |
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1012 while true do |
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1013 local <em>var_1</em>, ···, <em>var_n</em> = <em>f</em>() |
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1014 if <em>var_1</em> == nil then break end |
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1015 <em>block</em> |
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1016 end |
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1017 end |
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1018 </pre> |
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1019 |
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1020 <p> |
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1021 Note the following: |
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1022 |
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1023 <ul> |
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1024 |
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1025 <li> |
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1026 <code><em>exp</em></code> is evaluated only once. |
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1027 Its result is an <em>iterator</em> function. |
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1028 </li> |
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1029 |
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1030 <li> |
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1031 <code><em>f</em></code> is an invisible variable. |
395 | 1032 The name is here for explanatory purposes only. |
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1033 </li> |
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1034 |
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1035 <li> |
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1036 You can use <b>break</b> to exit a <b>for</b> loop. |
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1037 </li> |
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1038 |
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1039 <li> |
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1040 The loop variables <code><em>var_i</em></code> are local to the loop; |
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1041 you cannot use their values after the <b>for</b> ends. |
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1042 If you need these values, |
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1043 then assign them to other variables before breaking or exiting the loop. |
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1044 </li> |
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1045 |
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1046 </ul> |
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1047 |
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1048 |
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1049 |
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1050 |
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1051 <h4 heading><a name="fn_stmt">Function Calls as Statements</a></h4> |
395 | 1052 |
1053 <p> | |
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1054 To allow possible side-effects, |
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1055 function calls can be executed as statements: |
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1056 |
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1057 <pre> |
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1058 stat ::= functioncall |
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1059 </pre> |
395 | 1060 |
1061 <p> | |
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1062 In this case, all returned values are thrown away. |
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1063 Function calls are explained in <a href="#fn_calls">Function Calls</a>. |
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1064 |
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1065 |
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1066 |
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1067 <h4 heading><a name="local_stmt">Local Declarations</a></h4> |
395 | 1068 |
1069 <p> | |
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1070 Local variables can be declared anywhere inside a block. |
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1071 The declaration can include an initial assignment: |
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1072 |
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1073 <pre> |
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1074 stat ::= <b>local</b> namelist [‘<b>=</b>’ explist] |
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1075 </pre> |
395 | 1076 |
1077 <p> | |
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1078 If present, an initial assignment has the same semantics |
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1079 of a multiple assignment (see <a href="#assignment">Assignment</a>). |
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1080 Otherwise, all variables are initialized with <b>nil</b>. |
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1081 |
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1082 |
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1083 <p> |
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1084 A chunk is also a block (see <a href="#chunks">Chunks</a>), |
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1085 and so local variables can be declared in a chunk outside any explicit block. |
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1086 |
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1087 |
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1088 <p> |
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1089 The visibility rules for local variables are explained in <a href="#visibility">Visibility Rules</a>. |
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1090 |
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1091 |
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1092 <h4 heading><a name="template_stmt">Template Statements</a></h4> |
465 | 1093 |
1094 <p>Template statements are based on <a href="#template_expr">template exressions</a> and provide the full equivalent of <a href="http://en.wikipedia.org/wiki/JavaServer_Pages">JSP</a> but in a general way. Template statements write the equivalent template exression to standard output. For example:</p> | |
1095 | |
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1096 <pre><%=Html.encode[[ |
465 | 1097 local name = "Bob" |
1098 %> | |
469 | 1099 Hello <%= name %>! |
1100 Bye <%= name %>. | |
465 | 1101 <% |
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1102 ]]%></pre> |
465 | 1103 |
1104 <p>is equivalent to the code:</p> | |
1105 | |
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1106 <pre><%=Html.encode[[ |
465 | 1107 local name = "Bob" |
1108 require("luan:Io").stdout.write( %> | |
469 | 1109 Hello <%= name %>! |
1110 Bye <%= name %>. | |
465 | 1111 <% ) |
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1112 ]]%></pre> |
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1113 |
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1114 |
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1115 |
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1116 <h3 heading><a name="expressions">Expressions</a></h3> |
395 | 1117 |
1118 <p> | |
1119 The basic expressions in Luan are the following: | |
1120 | |
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1121 <pre> |
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1122 exp ::= prefixexp |
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1123 exp ::= <b>nil</b> | <b>false</b> | <b>true</b> |
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1124 exp ::= Numeral |
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1125 exp ::= LiteralString |
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1126 exp ::= functiondef |
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1127 exp ::= tableconstructor |
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1128 exp ::= ‘<b>...</b>’ |
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1129 exp ::= exp binop exp |
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1130 exp ::= unop exp |
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1131 prefixexp ::= var | functioncall | ‘<b>(</b>’ exp ‘<b>)</b>’ |
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1132 </pre> |
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1133 |
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1134 <p> |
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1135 Numerals and literal strings are explained in <a href="#lex">Lexical Conventions</a>; |
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1136 variables are explained in <a href="#vars">Variables</a>; |
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1137 function definitions are explained in <a href="#fn_def">Function Definitions</a>; |
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1138 function calls are explained in <a href="#fn_calls">Function Calls</a>; |
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1139 table constructors are explained in <a href="#constructors">Table Constructors</a>. |
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1140 Vararg expressions, |
562
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1141 denoted by three dots ('<code>...</code>'), can only be used when |
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1142 directly inside a vararg function; |
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1143 they are explained in <a href="#fn_def">Function Definitions</a>. |
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1144 |
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1145 |
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1146 <p> |
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1147 Binary operators comprise arithmetic operators (see <a href="#arithmetic">Arithmetic Operators</a>), |
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1148 relational operators (see <a href="#relational">Relational Operators</a>), logical operators (see <a href="#logical_ops">Logical Operators</a>), |
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1149 and the concatenation operator (see <a href="#concatenation">Concatenation</a>). |
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1150 Unary operators comprise the unary minus (see <a href="#arithmetic">Arithmetic Operators</a>), |
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1151 the unary logical <b>not</b> (see <a href="#logical_ops">Logical Operators</a>), |
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1152 and the unary <em>length operator</em> (see <a href="#length">The Length Operator</a>). |
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1153 |
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1154 |
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1155 <p> |
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1156 Both function calls and vararg expressions can result in multiple values. |
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1157 If a function call is used as a statement (see <a href="#fn_stmt">Function Calls as Statements</a>), |
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1158 then its return list is adjusted to zero elements, |
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1159 thus discarding all returned values. |
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1160 If an expression is used as the last (or the only) element |
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1161 of a list of expressions, |
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1162 then no adjustment is made |
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1163 (unless the expression is enclosed in parentheses). |
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1164 In all other contexts, |
395 | 1165 Luan adjusts the result list to one element, |
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1166 either discarding all values except the first one |
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1167 or adding a single <b>nil</b> if there are no values. |
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1168 |
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1169 |
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1170 <p> |
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1171 Here are some examples: |
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1172 |
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1173 <pre> |
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1174 f() -- adjusted to 0 results |
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1175 g(f(), x) -- f() is adjusted to 1 result |
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1176 g(x, f()) -- g gets x plus all results from f() |
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1177 a,b,c = f(), x -- f() is adjusted to 1 result (c gets nil) |
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1178 a,b = ... -- a gets the first vararg parameter, b gets |
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1179 -- the second (both a and b can get nil if there |
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1180 -- is no corresponding vararg parameter) |
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1181 |
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1182 a,b,c = x, f() -- f() is adjusted to 2 results |
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1183 a,b,c = f() -- f() is adjusted to 3 results |
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1184 return f() -- returns all results from f() |
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1185 return ... -- returns all received vararg parameters |
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1186 return x,y,f() -- returns x, y, and all results from f() |
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1187 {f()} -- creates a list with all results from f() |
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1188 {...} -- creates a list with all vararg parameters |
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1189 {f(), nil} -- f() is adjusted to 1 result |
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1190 </pre> |
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1191 |
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1192 <p> |
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1193 Any expression enclosed in parentheses always results in only one value. |
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1194 Thus, |
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1195 <code>(f(x,y,z))</code> is always a single value, |
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1196 even if <code>f</code> returns several values. |
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1197 (The value of <code>(f(x,y,z))</code> is the first value returned by <code>f</code> |
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1198 or <b>nil</b> if <code>f</code> does not return any values.) |
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1199 |
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1200 |
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1201 |
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1202 <h4 heading><a name="arithmetic">Arithmetic Operators</a></h4> |
395 | 1203 |
1204 <p> | |
1205 Luan supports the following arithmetic operators: | |
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1206 |
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1207 <ul> |
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1208 <li><b><code>+</code>: </b>addition</li> |
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1209 <li><b><code>-</code>: </b>subtraction</li> |
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1210 <li><b><code>*</code>: </b>multiplication</li> |
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1211 <li><b><code>/</code>: </b>division</li> |
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1212 <li><b><code>%</code>: </b>modulo</li> |
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1213 <li><b><code>^</code>: </b>exponentiation</li> |
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1214 <li><b><code>-</code>: </b>unary minus</li> |
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1215 </ul> |
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1216 |
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1217 <p> |
395 | 1218 Addition, subtraction, multiplication, division, and unary minus are the same as these operators in Java. Exponentiation uses Java's <a href="http://docs.oracle.com/javase/7/docs/api/java/lang/Math.html#pow(double,%20double)">Math.pow</a> function. |
371
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1219 |
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1220 <p> |
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1221 Modulo is defined as the remainder of a division |
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1222 that rounds the quotient towards minus infinite (floor division). |
395 | 1223 (The Java modulo operator is not used.) |
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1224 |
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1225 |
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1226 |
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1227 <h4 heading><a name="conversions">Coercions and Conversions</a></h4> |
396 | 1228 |
1229 <p> | |
465 | 1230 Luan generally avoids automatic conversions. |
1231 String concatenation automatically converts all of its arguments to strings. | |
1232 | |
1233 <p> | |
1234 Luan provides library functions for explicit type conversions. | |
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1235 |
396 | 1236 |
1237 | |
1238 | |
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1239 <h4 heading><a name="relational">Relational Operators</a></h4> |
396 | 1240 |
1241 <p> | |
1242 Luan supports the following relational operators: | |
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1243 |
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1244 <ul> |
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1245 <li><b><code>==</code>: </b>equality</li> |
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1246 <li><b><code>~=</code>: </b>inequality</li> |
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1247 <li><b><code><</code>: </b>less than</li> |
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1248 <li><b><code>></code>: </b>greater than</li> |
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1249 <li><b><code><=</code>: </b>less or equal</li> |
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1250 <li><b><code>>=</code>: </b>greater or equal</li> |
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1251 </ul><p> |
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1252 These operators always result in <b>false</b> or <b>true</b>. |
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1253 |
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1254 |
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1255 <p> |
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1256 Equality (<code>==</code>) first compares the type of its operands. |
371
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1257 If the types are different, then the result is <b>false</b>. |
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1258 Otherwise, the values of the operands are compared. |
396 | 1259 Strings, numbers, and binary values are compared in the obvious way (by value). |
1260 | |
1261 <p> | |
1262 Tables | |
371
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1263 are compared by reference: |
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1264 two objects are considered equal only if they are the same object. |
396 | 1265 Every time you create a new table, |
1266 it is different from any previously existing table. | |
1267 Closures are also compared by reference. | |
1268 | |
1269 <p> | |
417 | 1270 You can change the way that Luan compares tables |
464
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1271 by using the "eq" metamethod (see <a href="#meta">Metatables and Metamethods</a>). |
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1272 |
396 | 1273 <p> |
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1274 Java values are compared for equality with the Java <a href="http://docs.oracle.com/javase/7/docs/api/java/lang/Object.html#equals(java.lang.Object)"><code>equals</code></a> method. |
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1275 |
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1276 <p> |
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1277 Equality comparisons do not convert strings to numbers |
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1278 or vice versa. |
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1279 Thus, <code>"0"==0</code> evaluates to <b>false</b>, |
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1280 and <code>t[0]</code> and <code>t["0"]</code> denote different |
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1281 entries in a table. |
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1282 |
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1283 |
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1284 <p> |
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1285 The operator <code>~=</code> is exactly the negation of equality (<code>==</code>). |
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1286 |
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1287 |
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1288 <p> |
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1289 The order operators work as follows. |
396 | 1290 |
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1291 If both arguments are numbers, |
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1292 then they are compared following |
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1293 the usual rule for binary operations. |
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1294 Otherwise, if both arguments are strings, |
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1295 then their values are compared according to the current locale. |
396 | 1296 Otherwise, Luan tries to call the "lt" or the "le" |
464
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1297 metamethod (see <a href="#meta">Metatables and Metamethods</a>). |
562
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1298 A comparison <code>a > b</code> is translated to <code>b < a</code> |
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1299 and <code>a >= b</code> is translated to <code>b <= a</code>. |
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1300 |
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1301 |
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1302 |
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1303 |
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1304 |
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1305 <h4 heading><a name="logical_ops">Logical Operators</a></h4> |
396 | 1306 |
1307 <p> | |
1308 The logical operators in Luan are | |
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1309 <b>and</b>, <b>or</b>, and <b>not</b>. |
396 | 1310 The <b>and</b> and <b>or</b> operators consider both <b>false</b> and <b>nil</b> as false |
1311 and anything else as true. | |
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1312 Like the control structures (see <a href="#control">Control Structures</a>), |
396 | 1313 the <b>not</b> operator requires a boolean value. |
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1314 |
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1315 <p> |
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1316 The negation operator <b>not</b> always returns <b>false</b> or <b>true</b>. |
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1317 The conjunction operator <b>and</b> returns its first argument |
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1318 if this value is <b>false</b> or <b>nil</b>; |
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1319 otherwise, <b>and</b> returns its second argument. |
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1320 The disjunction operator <b>or</b> returns its first argument |
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1321 if this value is different from <b>nil</b> and <b>false</b>; |
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1322 otherwise, <b>or</b> returns its second argument. |
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1323 Both <b>and</b> and <b>or</b> use short-circuit evaluation; |
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1324 that is, |
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1325 the second operand is evaluated only if necessary. |
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1326 Here are some examples: |
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1327 |
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1328 <pre> |
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1329 10 or 20 --> 10 |
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1330 10 or error() --> 10 |
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1331 nil or "a" --> "a" |
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1332 nil and 10 --> nil |
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1333 false and error() --> false |
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1334 false and nil --> false |
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1335 false or nil --> nil |
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1336 10 and 20 --> 20 |
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1337 </pre> |
396 | 1338 |
1339 <p> | |
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1340 (In this manual, |
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1341 <code>--></code> indicates the result of the preceding expression.) |
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1342 |
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1343 |
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1344 |
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1345 <h4 heading><a name="concatenation">Concatenation</a></h4> |
396 | 1346 |
1347 <p> | |
1348 The string concatenation operator in Luan is | |
562
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1349 denoted by two dots ('<code>..</code>'). |
396 | 1350 All operands are converted to strings. |
1351 | |
1352 | |
1353 | |
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1354 <h4 heading><a name="length">The Length Operator</a></h4> |
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1355 |
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1356 <p> |
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1357 The length operator is denoted by the unary prefix operator <code>#</code>. |
396 | 1358 The length of a string is its number of characters. |
1359 The length of a binary is its number of bytes. | |
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1360 |
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1361 |
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1362 <p> |
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1363 A program can modify the behavior of the length operator for |
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1364 any table through the <code>__len</code> metamethod (see <a href="#meta">Metatables and Metamethods</a>). |
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1365 |
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1366 |
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1367 <p> |
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1368 Unless a <code>__len</code> metamethod is given, |
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1369 the length of a table <code>t</code> is defined |
396 | 1370 as the number of elements in <em>sequence</em>, |
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1371 that is, |
396 | 1372 the size of the set of its positive numeric keys is equal to <em>{1..n}</em> |
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1373 for some non-negative integer <em>n</em>. |
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1374 In that case, <em>n</em> is its length. |
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1375 Note that a table like |
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1376 |
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1377 <pre> |
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1378 {10, 20, nil, 40} |
562
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1379 </pre> |
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1380 |
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1381 <p> |
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1382 has a length of <code>2</code>, because that is the last key in sequence. |
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1383 |
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1384 |
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1385 |
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1386 |
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1387 |
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1388 <h4 heading><a name="precedence">Precedence</a></h4> |
396 | 1389 |
1390 <p> | |
1391 Operator precedence in Luan follows the table below, | |
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1392 from lower to higher priority: |
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1393 |
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1394 <pre> |
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1395 or |
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1396 and |
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1397 < > <= >= ~= == |
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1398 .. |
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1399 + - |
396 | 1400 * / % |
1401 unary operators (not # -) | |
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1402 ^ |
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1403 </pre> |
396 | 1404 |
1405 <p> | |
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1406 As usual, |
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1407 you can use parentheses to change the precedences of an expression. |
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1408 The concatenation ('<code>..</code>') and exponentiation ('<code>^</code>') |
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1409 operators are right associative. |
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1410 All other binary operators are left associative. |
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1411 |
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1412 |
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1413 |
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1414 |
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1415 |
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1416 <h4 heading><a name="constructors">Table Constructors</a></h4> |
396 | 1417 |
1418 <p> | |
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1419 Table constructors are expressions that create tables. |
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1420 Every time a constructor is evaluated, a new table is created. |
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1421 A constructor can be used to create an empty table |
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1422 or to create a table and initialize some of its fields. |
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1423 The general syntax for constructors is |
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1424 |
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1425 <pre> |
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1426 tableconstructor ::= ‘<b>{</b>’ fieldlist ‘<b>}</b>’ |
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1427 fieldlist ::= [field] {fieldsep [field]} |
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1428 field ::= ‘<b>[</b>’ exp ‘<b>]</b>’ ‘<b>=</b>’ exp | Name ‘<b>=</b>’ exp | exp |
604
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1429 fieldsep ::= ‘<b>,</b>’ | ‘<b>;</b>’ | <b>end_of_line</b> |
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1430 </pre> |
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1431 |
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1432 <p> |
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1433 Each field of the form <code>[exp1] = exp2</code> adds to the new table an entry |
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1434 with key <code>exp1</code> and value <code>exp2</code>. |
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1435 A field of the form <code>name = exp</code> is equivalent to |
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1436 <code>["name"] = exp</code>. |
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1437 Finally, fields of the form <code>exp</code> are equivalent to |
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1438 <code>[i] = exp</code>, where <code>i</code> are consecutive integers |
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1439 starting with 1. |
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1440 Fields in the other formats do not affect this counting. |
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1441 For example, |
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1442 |
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1443 <pre> |
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1444 a = { [f(1)] = g; "x", "y"; x = 1, f(x), [30] = 23; 45 } |
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1445 </pre> |
396 | 1446 |
1447 <p> | |
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1448 is equivalent to |
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1449 |
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1450 <pre> |
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1451 do |
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1452 local t = {} |
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1453 t[f(1)] = g |
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1454 t[1] = "x" -- 1st exp |
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1455 t[2] = "y" -- 2nd exp |
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1456 t.x = 1 -- t["x"] = 1 |
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1457 t[3] = f(x) -- 3rd exp |
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1458 t[30] = 23 |
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1459 t[4] = 45 -- 4th exp |
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1460 a = t |
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1461 end |
562
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1462 </pre> |
371
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1463 |
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1464 <p> |
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1465 The order of the assignments in a constructor is undefined. |
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1466 (This order would be relevant only when there are repeated keys.) |
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1467 |
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1468 |
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1469 <p> |
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1470 If the last field in the list has the form <code>exp</code> |
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1471 and the expression is a function call or a vararg expression, |
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1472 then all values returned by this expression enter the list consecutively |
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1473 (see <a href="#fn_calls">Function Calls</a>). |
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1474 |
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1475 |
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1476 <p> |
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1477 The field list can have an optional trailing separator, |
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1478 as a convenience for machine-generated code. |
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1479 |
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1480 |
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1481 |
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1482 |
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1483 |
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1484 <h4 heading><a name="fn_calls">Function Calls</a></h4> |
417 | 1485 |
1486 <p> | |
1487 A function call in Luan has the following syntax: | |
1488 | |
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1489 <pre> |
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1490 functioncall ::= prefixexp args |
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1491 </pre> |
417 | 1492 |
1493 <p> | |
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1494 In a function call, |
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1495 first prefixexp and args are evaluated. |
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1496 If the value of prefixexp has type <em>function</em>, |
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1497 then this function is called |
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1498 with the given arguments. |
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1499 Otherwise, the prefixexp "call" metamethod is called, |
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1500 having as first parameter the value of prefixexp, |
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1501 followed by the original call arguments |
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1502 (see <a href="#meta">Metatables and Metamethods</a>). |
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1503 |
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1504 |
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1505 <p> |
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1506 Arguments have the following syntax: |
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1507 |
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1508 <pre> |
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1509 args ::= ‘<b>(</b>’ [explist] ‘<b>)</b>’ |
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1510 args ::= tableconstructor |
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1511 args ::= LiteralString |
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1512 </pre> |
417 | 1513 |
1514 <p> | |
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1515 All argument expressions are evaluated before the call. |
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1516 A call of the form <code>f{<em>fields</em>}</code> is |
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1517 syntactic sugar for <code>f({<em>fields</em>})</code>; |
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1518 that is, the argument list is a single new table. |
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1519 A call of the form <code>f'<em>string</em>'</code> |
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1520 (or <code>f"<em>string</em>"</code> or <code>f[[<em>string</em>]]</code>) |
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1521 is syntactic sugar for <code>f('<em>string</em>')</code>; |
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1522 that is, the argument list is a single literal string. |
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1523 |
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1524 |
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1525 <p> |
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1526 A call of the form <code>return <em>functioncall</em></code> is called |
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1527 a <em>tail call</em>. |
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1528 Luan implements <em>proper tail calls</em> |
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1529 (or <em>proper tail recursion</em>): |
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1530 in a tail call, |
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1531 the called function reuses the stack entry of the calling function. |
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1532 Therefore, there is no limit on the number of nested tail calls that |
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1533 a program can execute. |
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1534 However, a tail call erases any debug information about the |
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1535 calling function. |
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1536 Note that a tail call only happens with a particular syntax, |
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1537 where the <b>return</b> has one single function call as argument; |
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1538 this syntax makes the calling function return exactly |
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1539 the returns of the called function. |
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1540 So, none of the following examples are tail calls: |
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1541 |
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1542 <pre> |
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1543 return (f(x)) -- results adjusted to 1 |
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1544 return 2 * f(x) |
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1545 return x, f(x) -- additional results |
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1546 f(x); return -- results discarded |
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1547 return x or f(x) -- results adjusted to 1 |
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1548 </pre> |
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1549 |
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1550 |
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1551 |
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1552 |
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1553 <h4 heading><a name="fn_def">Function Definitions</a></h4> |
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1554 |
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1555 <p> |
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1556 The syntax for function definition is |
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1557 |
562
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1558 <pre> |
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1559 functiondef ::= <b>function</b> funcbody |
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1560 funcbody ::= ‘<b>(</b>’ [parlist] ‘<b>)</b>’ block <b>end</b> |
562
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1561 </pre> |
371
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1562 |
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1563 <p> |
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1564 The following syntactic sugar simplifies function definitions: |
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1565 |
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1566 <pre> |
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1567 stat ::= <b>function</b> funcname funcbody |
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1568 stat ::= <b>local</b> <b>function</b> Name funcbody |
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1569 funcname ::= Name {‘<b>.</b>’ Name} [‘<b>:</b>’ Name] |
562
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1570 </pre> |
417 | 1571 |
1572 <p> | |
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1573 The statement |
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1574 |
562
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1575 <pre> |
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1576 function f () <em>body</em> end |
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1577 </pre> |
417 | 1578 |
1579 <p> | |
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1580 translates to |
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1581 |
562
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1582 <pre> |
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1583 f = function () <em>body</em> end |
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1584 </pre> |
417 | 1585 |
1586 <p> | |
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1587 The statement |
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1588 |
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1589 <pre> |
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1590 function t.a.b.c.f () <em>body</em> end |
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1591 </pre> |
417 | 1592 |
1593 <p> | |
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1594 translates to |
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1595 |
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1596 <pre> |
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1597 t.a.b.c.f = function () <em>body</em> end |
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1598 </pre> |
417 | 1599 |
1600 <p> | |
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1601 The statement |
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1602 |
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1603 <pre> |
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1604 local function f () <em>body</em> end |
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1605 </pre> |
417 | 1606 |
1607 <p> | |
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1608 translates to |
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1609 |
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1610 <pre> |
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1611 local f; f = function () <em>body</em> end |
562
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1612 </pre> |
417 | 1613 |
1614 <p> | |
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1615 not to |
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1616 |
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1617 <pre> |
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1618 local f = function () <em>body</em> end |
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1619 </pre> |
417 | 1620 |
1621 <p> | |
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1622 (This only makes a difference when the body of the function |
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1623 contains references to <code>f</code>.) |
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1624 |
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|
1625 |
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1626 <p> |
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1627 A function definition is an executable expression, |
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1628 whose value has type <em>function</em>. |
417 | 1629 When Luan precompiles a chunk, |
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1630 all its function bodies are precompiled too. |
417 | 1631 Then, whenever Luan executes the function definition, |
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1632 the function is <em>instantiated</em> (or <em>closed</em>). |
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1633 This function instance (or <em>closure</em>) |
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1634 is the final value of the expression. |
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1635 |
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1636 |
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1637 <p> |
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1638 Parameters act as local variables that are |
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1639 initialized with the argument values: |
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1640 |
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1641 <pre> |
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1642 parlist ::= namelist [‘<b>,</b>’ ‘<b>...</b>’] | ‘<b>...</b>’ |
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1643 </pre> |
417 | 1644 |
1645 <p> | |
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1646 When a function is called, |
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1647 the list of arguments is adjusted to |
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1648 the length of the list of parameters, |
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1649 unless the function is a <em>vararg function</em>, |
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1650 which is indicated by three dots ('<code>...</code>') |
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1651 at the end of its parameter list. |
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1652 A vararg function does not adjust its argument list; |
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1653 instead, it collects all extra arguments and supplies them |
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1654 to the function through a <em>vararg expression</em>, |
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1655 which is also written as three dots. |
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1656 The value of this expression is a list of all actual extra arguments, |
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1657 similar to a function with multiple results. |
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1658 If a vararg expression is used inside another expression |
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1659 or in the middle of a list of expressions, |
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1660 then its return list is adjusted to one element. |
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1661 If the expression is used as the last element of a list of expressions, |
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1662 then no adjustment is made |
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1663 (unless that last expression is enclosed in parentheses). |
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1664 |
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1665 |
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1666 <p> |
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1667 As an example, consider the following definitions: |
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1668 |
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1669 <pre> |
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1670 function f(a, b) end |
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1671 function g(a, b, ...) end |
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1672 function r() return 1,2,3 end |
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1673 </pre> |
417 | 1674 |
1675 <p> | |
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1676 Then, we have the following mapping from arguments to parameters and |
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1677 to the vararg expression: |
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1678 |
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1679 <pre> |
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1680 CALL PARAMETERS |
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1681 |
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1682 f(3) a=3, b=nil |
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1683 f(3, 4) a=3, b=4 |
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1684 f(3, 4, 5) a=3, b=4 |
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1685 f(r(), 10) a=1, b=10 |
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1686 f(r()) a=1, b=2 |
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1687 |
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1688 g(3) a=3, b=nil, ... --> (nothing) |
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1689 g(3, 4) a=3, b=4, ... --> (nothing) |
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1690 g(3, 4, 5, 8) a=3, b=4, ... --> 5 8 |
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1691 g(5, r()) a=5, b=1, ... --> 2 3 |
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1692 </pre> |
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1693 |
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1694 <p> |
464
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1695 Results are returned using the <b>return</b> statement (see <a href="#control">Control Structures</a>). |
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1696 If control reaches the end of a function |
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1697 without encountering a <b>return</b> statement, |
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1698 then the function returns with no results. |
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1699 |
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1700 |
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1701 <h4 heading><a name="template_expr">Template Expressions</a></h4> |
465 | 1702 |
1703 <p>Luan template expression are based on <a href="http://en.wikipedia.org/wiki/JavaServer_Pages">JSP</a>. Template expressions return multiple values. Here is an example:</p> | |
1704 | |
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1705 <pre><%=Html.encode[[ |
465 | 1706 local name = "Bob" |
469 | 1707 write( %>Hello <%= name %>!<% ) |
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1708 ]]%></pre> |
465 | 1709 |
1710 <p>This is equivalent to the code:</p> | |
1711 | |
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1712 <pre> |
465 | 1713 local name = "Bob" |
1714 write( "Hello ", name, "!" ) | |
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1715 </pre> |
465 | 1716 |
1717 <p>The strings in template expressions may be multiple lines.</p> | |
1718 | |
417 | 1719 |
1720 | |
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1721 <h3 heading><a name="visibility">Visibility Rules</a></h3> |
417 | 1722 |
1723 <p> | |
1724 Luan is a lexically scoped language. | |
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1725 The scope of a local variable begins at the first statement after |
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1726 its declaration and lasts until the last non-void statement |
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1727 of the innermost block that includes the declaration. |
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1728 Consider the following example: |
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1729 |
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1730 <pre> |
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1731 x = 10 -- global variable |
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1732 do -- new block |
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1733 local x = x -- new 'x', with value 10 |
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1734 print(x) --> 10 |
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1735 x = x+1 |
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1736 do -- another block |
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1737 local x = x+1 -- another 'x' |
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1738 print(x) --> 12 |
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1739 end |
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1740 print(x) --> 11 |
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1741 end |
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1742 print(x) --> 10 (the global one) |
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1743 </pre> |
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1744 |
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1745 <p> |
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1746 Notice that, in a declaration like <code>local x = x</code>, |
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1747 the new <code>x</code> being declared is not in scope yet, |
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1748 and so the second <code>x</code> refers to the outside variable. |
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1749 |
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1750 |
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1751 <p> |
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1752 Because of the lexical scoping rules, |
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1753 local variables can be freely accessed by functions |
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1754 defined inside their scope. |
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1755 A local variable used by an inner function is called |
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1756 an <em>upvalue</em>, or <em>external local variable</em>, |
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1757 inside the inner function. |
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1758 |
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1759 |
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1760 <p> |
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1761 Notice that each execution of a <b>local</b> statement |
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1762 defines new local variables. |
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1763 Consider the following example: |
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1764 |
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1765 <pre> |
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1766 a = {} |
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1767 local x = 20 |
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1768 for i=1,10 do |
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1769 local y = 0 |
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1770 a[i] = function () y=y+1; return x+y end |
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1771 end |
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1772 </pre> |
417 | 1773 |
1774 <p> | |
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1775 The loop creates ten closures |
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1776 (that is, ten instances of the anonymous function). |
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1777 Each of these closures uses a different <code>y</code> variable, |
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1778 while all of them share the same <code>x</code>. |
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1779 |
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1780 |
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1781 |
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1782 |
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1783 |
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1784 <h2 heading><a name="libs">Standard Libraries</a></h2> |
468 | 1785 |
1786 <p> | |
1787 The standard Luan libraries provide useful functions | |
1788 that are implemented both in Java and in Luan itself. | |
1789 How each function is implemented shouldn't matter to the user. | |
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1790 Some of these functions provide essential services to the language |
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1791 (e.g., <a href="#Luan.type"><code>type</code></a> and <a href="#Luan.get_metatable"><code>get_metatable</code></a>); |
468 | 1792 others provide access to "outside" services (e.g., I/O). |
1793 | |
1794 | |
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1795 <h3 heading><a name="default_lib">Default Environment</a></h3> |
468 | 1796 |
1797 <p> | |
1798 These are provided by default as local variables for any Luan code as described in <a href="#env">Environments</a>. | |
1799 | |
470 | 1800 |
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1801 <h4 heading><a name="require"><code>java ()</code></a></h4> |
470 | 1802 |
1803 <p> | |
1804 This function enables Java in the current chunk if that chunk has permission to use Java. If the chunk doesn't have permission to use Java, then an error is thrown. | |
1805 | |
1806 | |
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1807 <h4 heading><a name="require"><code>require (mod_uri)</code></a></h4> |
470 | 1808 |
1809 <p> | |
1810 Example use: | |
1811 | |
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1812 <pre> |
470 | 1813 local Table = require "luan:Table" |
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1814 </pre> |
470 | 1815 |
1816 <p> | |
1817 Could be defined as: | |
1818 | |
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1819 <pre> |
470 | 1820 local function require(mod_name) |
476 | 1821 return <a href="#Package.load">Package.load</a>(mod_name) or <a href="#Luan.error">Luan.error</a>("module '"..mod_name.."' not found") |
470 | 1822 end |
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1823 </pre> |
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1824 |
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1825 |
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1826 <h3 heading><a name="luan_lib">Basic Functions</a></h3> |
470 | 1827 |
1828 <p> | |
1829 Include this library by: | |
1830 | |
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1831 <pre> |
470 | 1832 local Luan = require "luan:Luan" |
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1833 </pre> |
470 | 1834 |
476 | 1835 <p> |
470 | 1836 The basic library provides basic functions to Luan that don't depend on other libaries. |
1837 | |
1838 | |
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1839 <h4 heading><a name="Luan.assert" href="#Luan.assert"><code>Luan.assert (v [, message])</code></a></h4> |
470 | 1840 |
1841 <p> | |
1842 Could be defined as: | |
1843 | |
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1844 <pre> |
470 | 1845 function Luan.assert(v,message) |
472 | 1846 return v or <a href="#Luan.error">Luan.error</a>(message or "assertion failed!") |
470 | 1847 end |
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1848 </pre> |
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1849 |
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1850 |
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1851 <h4 heading><a name="Luan.assert_binary" href="#Luan.assert_binary"><code>Luan.assert_binary (v)</code></a></h4> |
470 | 1852 |
1853 <p> | |
1854 Could be defined as: | |
1855 | |
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1856 <pre> |
470 | 1857 function Luan.assert_binary(v) |
1858 local v_type = Luan.type(v) | |
472 | 1859 return v_type == "binary" and v or <a href="#Luan.error">Luan.error</a>("bad argument #1 (binary expected, got "..v_type..")") |
470 | 1860 end |
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1861 </pre> |
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1862 |
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1863 |
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1864 <h4 heading><a name="Luan.assert_boolean" href="#Luan.assert_boolean"><code>Luan.assert_boolean (v)</code></a></h4> |
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1865 |
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1866 <p> |
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1867 Like <a href="#Luan.assert_binary"><code>assert_binary</code></a> but for type <code>boolean</code>. |
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1868 |
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1869 |
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1870 <h4 heading><a name="Luan.assert_function" href="#Luan.assert_function"><code>Luan.assert_function (v)</code></a></h4> |
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1871 |
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1872 <p> |
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1873 Like <a href="#Luan.assert_binary"><code>assert_binary</code></a> but for type <code>function</code>. |
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1874 |
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1875 |
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1876 <h4 heading><a name="Luan.assert_integer" href="#Luan.assert_integer"><code>Luan.assert_integer (v)</code></a></h4> |
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1877 |
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1878 <p> |
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1879 Asserts that <code>v</code> can be converted to Java type <a href="https://docs.oracle.com/javase/8/docs/api/java/lang/Integer.html">Integer</a> and returns an Integer. |
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1880 |
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1881 |
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1882 <h4 heading><a name="Luan.assert_long" href="#Luan.assert_long"><code>Luan.assert_long (v)</code></a></h4> |
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1883 |
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1884 <p> |
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1885 Asserts that <code>v</code> can be converted to Java type <a href="https://docs.oracle.com/javase/8/docs/api/java/lang/Long.html">Long</a> and returns a Long. |
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1886 |
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1887 |
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1888 <h4 heading><a name="Luan.assert_number" href="#Luan.assert_number"><code>Luan.assert_number (v)</code></a></h4> |
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1889 |
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1890 <p> |
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1891 Like <a href="#Luan.assert_binary"><code>assert_binary</code></a> but for type <code>number</code>. |
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1892 |
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1893 |
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1894 <h4 heading><a name="Luan.assert_string" href="#Luan.assert_string"><code>Luan.assert_string (v)</code></a></h4> |
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1895 |
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1896 <p> |
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1897 Like <a href="#Luan.assert_binary"><code>assert_binary</code></a> but for type <code>string</code>. |
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1898 |
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1899 |
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1900 <h4 heading><a name="Luan.assert_table" href="#Luan.assert_table"><code>Luan.assert_table (v)</code></a></h4> |
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1901 |
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1902 <p> |
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1903 Like <a href="#Luan.assert_binary"><code>assert_binary</code></a> but for type <code>table</code>. |
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1904 |
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1905 |
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1906 <h4 heading><a name="Luan.do_file" href="#Luan.do_file"><code>Luan.do_file ([uri])</code></a></h4> |
470 | 1907 |
1908 <p> | |
1909 Could be defined as: | |
1910 | |
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1911 <pre> |
470 | 1912 function Luan.do_file(uri) |
474 | 1913 return <a href="#Luan.load_file">Luan.load_file</a>(uri)() |
470 | 1914 end |
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1915 </pre> |
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1916 |
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1917 |
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1918 |
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1919 <h4 heading><a name="Luan.error" href="#Luan.error"><code>Luan.error (message)</code></a></h4> |
470 | 1920 |
1921 <p> | |
482 | 1922 Throws an error containing the message. |
1923 | |
1924 <p> | |
1925 Could be defined as: | |
1926 | |
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1927 <pre> |
482 | 1928 function Luan.error(message) |
1929 <a href="#Luan.new_error">Luan.new_error</a>(message).throw() | |
1930 end | |
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1931 </pre> |
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1932 |
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1933 |
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1934 |
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1935 <h4 heading><a name="Luan.get_metatable" href="#Luan.get_metatable"><code>Luan.get_metatable (table)</code></a></h4> |
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1936 |
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1937 <p> |
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1938 If <code>table</code> does not have a metatable, returns <b>nil</b>. |
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1939 Otherwise, |
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1940 if the table's metatable has a <code>"__metatable"</code> field, |
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1941 returns the associated value. |
470 | 1942 Otherwise, returns the metatable of the given table. |
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1943 |
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1944 |
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1945 <h4 heading><a name="Luan.ipairs" href="#Luan.ipairs"><code>Luan.ipairs (t)</code></a></h4> |
474 | 1946 |
1947 <p> | |
1948 Returns an iterator function | |
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1949 so that the construction |
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1950 |
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1951 <pre> |
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1952 for i,v in ipairs(t) do <em>body</em> end |
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1953 </pre> |
474 | 1954 |
1955 <p> | |
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1956 will iterate over the key–value pairs |
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1957 (<code>1,t[1]</code>), (<code>2,t[2]</code>), ..., |
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1958 up to the first nil value. |
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1959 |
474 | 1960 <p> |
1961 Could be defined as: | |
1962 | |
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1963 <pre> |
474 | 1964 function Luan.ipairs(t) |
1965 local i = 0 | |
1966 return function() | |
1967 if i < #t then | |
1968 i = i + 1 | |
1969 return i, t[i] | |
1970 end | |
1971 end | |
1972 end | |
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1973 </pre> |
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1974 |
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1975 |
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1976 |
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1977 <h4 heading><a name="Luan.load" href="#Luan.load"><code>Luan.load (text, [source_name [env, [, allow_expression]]])</code></a></h4> |
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1978 |
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1979 <p> |
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1980 Loads a chunk. |
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1981 |
474 | 1982 <p> |
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1983 The <code>text</code> is compiled. |
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1984 If there are no syntactic errors, |
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1985 returns the compiled chunk as a function; |
474 | 1986 otherwise, throws an error. |
1987 | |
1988 <p> | |
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1989 The <code>source_name</code> parameter is a string saying where the text came from. It is used to produce error messages. |
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1990 |
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1991 <p> |
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1992 If the <code>env</code> parameter is supplied, it becomes the <code>_ENV</code> of the chunk. |
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1993 |
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1994 <p> |
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1995 If the <code>allow_expression</code> parameter is <code>true</code> then the entire text can be nothing more than an expression in which case the chunk returns the value of this expression. |
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1996 |
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1997 |
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1998 <h4 heading><a name="Luan.load_file" href="#Luan.load_file"><code>Luan.load_file (file_uri [, add_extension])</code></a></h4> |
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1999 |
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2000 <p> |
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2001 Similar to <a href="#Luan.load"><code>load</code></a>, |
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2002 but gets the chunk from file <code>file_uri</code> |
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2003 or from the standard input, |
474 | 2004 if no file uri is given. |
2005 | |
2006 <p> | |
2007 Could be defined as: | |
2008 | |
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2009 <pre> |
474 | 2010 function Luan.load_file(file_uri,add_extension) |
2011 file_uri = file_uri or "stdin:" | |
2012 local f = Io.uri(file_uri,add_extension) | |
2013 f.exists() or <a href="#Luan.error">Luan.error</a>("file '"..file_uri.."' not found") | |
2014 return <a href="#Luan.load">Luan.load</a>( f.read_text(), file_uri ) | |
2015 end | |
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2016 </pre> |
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2017 |
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2018 |
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2019 <h4 heading><a name="Luan.new_error" href="#Luan.new_error"><code>Luan.new_error (message)</code></a></h4> |
562
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2020 |
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2021 <p> |
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2022 Creates a new error table containing the message assigned to "<code>message</code>". The error table also contains a <code>throw</code> function which throws the error. The table also contains a list of stack trace elements where each stack trace element is a table containing "<code>source</code>", "<code>line</code>", and possible "<code>call_to</code>". The table also has a metatable containing "<code>__to_string</code>" to render the error. |
482 | 2023 |
2024 <p> | |
2025 To print the current stack trace, you could do: | |
2026 | |
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2027 <pre> |
482 | 2028 Io.print( Luan.new_error "stack" ) |
562
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2029 </pre> |
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2030 |
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2031 |
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2032 <h4 heading><a name="Luan.pairs" href="#Luan.pairs"><code>Luan.pairs (t)</code></a></h4> |
562
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2033 |
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2034 <p> |
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2035 If <code>t</code> has a metamethod <code>__pairs</code>, |
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2036 calls it with <code>t</code> as argument and returns the |
475 | 2037 result from the call. |
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2038 |
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2039 |
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2040 <p> |
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2041 Otherwise, |
475 | 2042 returns a function |
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2043 so that the construction |
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2044 |
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2045 <pre> |
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2046 for k,v in pairs(t) do <em>body</em> end |
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2047 </pre> |
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2048 |
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2049 <p> |
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2050 will iterate over all key–value pairs of table <code>t</code>. |
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2051 |
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2052 |
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2053 |
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2054 <h4 heading><a name="Luan.pcall" href="#Luan.pcall"><code>Luan.pcall (f [, arg1, ···])</code></a></h4> |
562
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2055 |
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2056 <p> |
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2057 Calls function <code>f</code> with |
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2058 the given arguments in <em>protected mode</em>. |
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2059 This means that any error inside <code>f</code> is not propagated; |
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2060 instead, <code>pcall</code> catches the error |
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2061 and returns a status code. |
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2062 Its first result is the status code (a boolean), |
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2063 which is true if the call succeeds without errors. |
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2064 In such case, <code>pcall</code> also returns all results from the call, |
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2065 after this first result. |
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2066 In case of any error, <code>pcall</code> returns <b>false</b> plus the error. |
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2067 |
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2068 |
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2069 |
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2070 |
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2071 <p> |
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2072 <hr><h3><a name="pdf-print"><code>print (···)</code></a></h3> |
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2073 Receives any number of arguments |
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2074 and prints their values to <code>stdout</code>, |
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2075 using the <a href="#pdf-tostring"><code>tostring</code></a> function to convert each argument to a string. |
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2076 <code>print</code> is not intended for formatted output, |
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2077 but only as a quick way to show a value, |
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2078 for instance for debugging. |
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2079 For complete control over the output, |
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2080 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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2081 |
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2082 |
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2083 |
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2084 <h4 heading><a name="Luan.range" href="#Luan.range"><code>Luan.range (start, stop [, step])</code></a></h4> |
476 | 2085 |
2086 <p> | |
2087 Based on <a href="https://docs.python.org/2/library/functions.html#range">the Python range() function</a>, this lets one iterate through a sequence of numbers. | |
2088 | |
2089 <p> | |
2090 Example use: | |
2091 | |
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2092 <pre> |
476 | 2093 for i in range(1,10) do |
2094 Io.print("count up:",i) | |
2095 end | |
2096 for i in range(10,0,-1) do | |
2097 Io.print("count down:",i) | |
2098 end | |
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2099 </pre> |
476 | 2100 |
2101 <p> | |
2102 Could be defined as: | |
2103 | |
562
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2104 <pre> |
476 | 2105 function Luan.range(start, stop, step) |
2106 step = step or 1 | |
478 | 2107 step == 0 and <a href="#Luan.error">Luan.error</a> "bad argument #3 (step may not be zero)" |
476 | 2108 local i = start |
2109 return function() | |
2110 if step > 0 and i <= stop or step < 0 and i >= stop then | |
2111 local rtn = i | |
2112 i = i + step | |
2113 return rtn | |
2114 end | |
2115 end | |
2116 end | |
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2117 </pre> |
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2118 |
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2119 |
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2120 |
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2121 <h4 heading><a name="Luan.raw_equal" href="#Luan.raw_equal"><code>Luan.raw_equal (v1, v2)</code></a></h4> |
562
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2122 |
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2123 <p> |
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2124 Checks whether <code>v1</code> is equal to <code>v2</code>, |
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2125 without invoking any metamethod. |
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2126 Returns a boolean. |
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2127 |
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2128 |
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2129 |
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2130 <h4 heading><a name="Luan.raw_get" href="#Luan.raw_get"><code>Luan.raw_get (table, index)</code></a></h4> |
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2131 |
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2132 <p> |
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2133 Gets the real value of <code>table[index]</code>, |
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2134 without invoking any metamethod. |
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2135 <code>table</code> must be a table; |
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2136 <code>index</code> may be any value. |
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2137 |
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2138 |
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2139 |
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2140 <h4 heading><a name="Luan.raw_len" href="#Luan.raw_len"><code>Luan.raw_len (v)</code></a></h4> |
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2141 |
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2142 <p> |
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2143 Returns the length of the object <code>v</code>, |
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2144 which must be a table or a string, |
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2145 without invoking any metamethod. |
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2146 Returns an integer. |
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2147 |
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2148 |
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2149 |
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2150 <h4 heading><a name="Luan.raw_set" href="#Luan.raw_set"><code>Luan.raw_set (table, index, value)</code></a></h4> |
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2151 |
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2152 <p> |
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2153 Sets the real value of <code>table[index]</code> to <code>value</code>, |
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2154 without invoking any metamethod. |
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2155 <code>table</code> must be a table, |
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2156 <code>index</code> any value different from <b>nil</b>, |
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2157 and <code>value</code> any Lua value. |
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2158 |
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2159 |
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2160 <h4 heading><a name="Luan.set_metatable" href="#Luan.set_metatable"><code>Luan.set_metatable (table, metatable)</code></a></h4> |
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2161 |
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2162 <p> |
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2163 Sets the metatable for the given table. |
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2164 If <code>metatable</code> is <b>nil</b>, |
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2165 removes the metatable of the given table. |
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2166 If the original metatable has a <code>"__metatable"</code> field, |
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2167 raises an error. |
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2168 |
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2169 |
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2170 |
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2171 <h4 heading><a name="Luan.to_string" href="#Luan.to_string"><code>Luan.to_string (v)</code></a></h4> |
475 | 2172 |
2173 <p> | |
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2174 Receives a value of any type and |
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2175 converts it to a string in a human-readable format. |
475 | 2176 |
2177 <p> | |
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2178 If the metatable of <code>v</code> has a <code>"__to_string"</code> field, |
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2179 then <code>to_string</code> calls the corresponding value |
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2180 with <code>v</code> as argument, |
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2181 and uses the result of the call as its result. |
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2182 |
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2183 |
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2184 |
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2185 <h4 heading><a name="Luan.try" href="#Luan.try"><code>Luan.try (t, ···)</code></a></h4> |
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2186 |
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2187 <p> |
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2188 Implements try-catch as found in other languages where each block is in table <code>t</code>. <code>t[1]</code> is the "try" block. The <code>t.catch</code> and <code>t.finally</code> blocks are optional. Any extra arguments are passed to the "try" function. Returns the result of the "try" block or the "catch" block. |
476 | 2189 |
2190 <p> | |
2191 Example use: | |
2192 | |
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2193 <pre> |
476 | 2194 try { |
2195 function() | |
2196 a_dangerous_fn() | |
2197 end; | |
2198 catch = function(e) | |
2199 -- handle error | |
2200 end; | |
2201 finally = function() | |
2202 -- clean up | |
2203 end; | |
2204 } | |
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2205 </pre> |
476 | 2206 |
482 | 2207 <p> |
2208 Could be defined as: | |
2209 | |
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2210 <pre> |
482 | 2211 function Luan.try(t) |
2212 local r = { <a href="#Luan.pcall">Luan.pcall</a>(t[1]) } | |
2213 if r[1] then | |
2214 Table.remove(r,1) | |
2215 elseif t.catch ~= nil then | |
2216 r = { t.catch(r[2]) } | |
2217 else | |
2218 t.finally and t.finally() | |
2219 r[2].throw() | |
2220 end | |
2221 t.finally and t.finally() | |
2222 return Table.unpack(r) | |
2223 end | |
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2224 </pre> |
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2225 |
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2226 |
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2227 <h4 heading><a name="Luan.type" href="#Luan.type"><code>Luan.type (v)</code></a></h4> |
475 | 2228 |
2229 <p> | |
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2230 Returns the type of its only argument, coded as a string. |
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2231 The possible results of this function are |
562
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2232 "<code>nil</code>" (a string, not the value <b>nil</b>), |
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2233 "<code>number</code>", |
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2234 "<code>string</code>", |
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2235 "<code>binary</code>", |
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2236 "<code>boolean</code>", |
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2237 "<code>table</code>", |
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2238 "<code>function</code>", |
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2239 and "<code>java</code>". |
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2240 |
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2241 |
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2242 <h4 heading><a name="Luan.values" href="#Luan.values"><code>Luan.values (···)</code></a></h4> |
476 | 2243 |
2244 <p> | |
2245 Returns a function so that the construction | |
2246 | |
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2247 <pre> |
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2248 for v in Luan.values(···) do <em>body</em> end |
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2249 </pre> |
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2250 |
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2251 <p> |
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2252 will iterate over all values of <code>···</code>. |
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2253 |
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2254 |
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2255 |
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2256 <h4 heading><a name="Luan.VERSION" href="#Luan.VERSION"><code>Luan.VERSION</code></a></h4> |
475 | 2257 |
2258 <p> | |
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2259 A global variable (not a function) that |
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2260 holds a string containing the current interpreter version. |
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2261 The current value of this variable is "<code><%=Luan.VERSION%></code>". |
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2262 |
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2263 |
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2264 |
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2265 |
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2266 |
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2267 |
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2268 <h3 heading><a name="package_lib">Modules</a></h3> |
476 | 2269 |
2270 <p> | |
2271 Include this library by: | |
2272 | |
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2273 <pre> |
476 | 2274 local Package = require "luan:Package" |
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2275 </pre> |
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2276 |
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2277 <p> |
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2278 The package library provides basic |
476 | 2279 facilities for loading modules in Luan. |
2280 | |
2281 | |
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2282 <h4 heading><a name="Package.load" href="#Package.load"><code>Package.load (mod_uri)</code></a></h4> |
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2283 |
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2284 <p> |
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2285 Loads the given module. |
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2286 The function starts by looking into the <a href="#Package.loaded"><code>Package.loaded</code></a> table |
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2287 to determine whether <code>mod_uri</code> is already loaded. |
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2288 If it is, then <code>Package.load</code> returns the value stored |
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2289 at <code>Package.loaded[mod_uri]</code>. |
476 | 2290 Otherwise, it tries to load a new value for the module. |
2291 | |
2292 <p> | |
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2293 To load a new value, <code>Package.load</code> first checks if <code>mod_uri</code> starts with "<b>java:</b>". If yes, then this is a Java class which is loaded by special Java code. |
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2294 |
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2295 <p> |
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2296 If <code>mod_uri</code> is not a Java class, then <code>Package.load</code> tries to read the text of the file referred to by <code>mod_uri</code> (using <code>add_extension</code>=true). If the file doesn't exist, then <code>Package.load</code> returns <b>nil</b>. If the file exists, then its content is compiled into a chunk calling <a href="#Luan.load"><code>Luan.load</code></a> and passing in an empty table as the <code>env</code> value. This chunk is run passing in <code>mod_uri</code> as an argument. If the chunk returns a value other than <b>nil</b>, then that value is the value of this module. Otherwise the <code>env</code> that was passed in is the value of this module. |
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2297 |
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2298 <p> |
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2299 If a new value for the module successful loaded, then it is stored in <code>Package.loaded[mod_uri]</code>. The value is returned. |
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2300 |
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2301 |
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2302 |
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2303 |
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2304 <h4 heading><a name="Package.loaded" href="#Package.loaded"><code>Package.loaded</code></a></h4> |
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2305 |
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2306 |
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2307 <p> |
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2308 A table used by <a href="#Package.load"><code>Package.load</code></a> to control which |
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2309 modules are already loaded. |
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2310 When you load a module <code>mod_uri</code> and |
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2311 <code>Package.loaded[mod_uri]</code> is not <b>nil</b>, |
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2312 <a href="#Package.load"><code>Package.load</code></a> simply returns the value stored there. |
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2313 |
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2314 |
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2315 <p> |
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2316 This variable is only a reference to the real table; |
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2317 assignments to this variable do not change the |
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2318 table used by <a href="#Package.load"><code>Package.load</code></a>. |
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2319 |
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2320 |
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2321 |
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2322 |
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2323 |
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2324 |
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2325 <h3 heading><a name="string_lib">String Manipulation</a></h3> |
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2326 |
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2327 <p> |
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2328 Include this library by: |
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2329 |
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2330 <pre> |
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2331 local String = require "luan:String" |
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2332 </pre> |
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2333 |
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2334 <p> |
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2335 This library provides generic functions for string manipulation, |
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2336 such as finding and extracting substrings, and pattern matching. |
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2337 When indexing a string in Luan, the first character is at position 1 |
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2338 (not at 0, as in Java). |
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2339 Indices are allowed to be negative and are interpreted as indexing backwards, |
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2340 from the end of the string. |
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2341 Thus, the last character is at position -1, and so on. |
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2342 |
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2343 |
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2344 |
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2345 <h4 heading><a name="String.char" href="#String.char"><code>String.char (···)</code></a></h4> |
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2346 |
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2347 <p> |
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2348 Receives zero or more integers. |
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2349 Returns a string with length equal to the number of arguments, |
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2350 in which each character has the internal numerical code equal |
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2351 to its corresponding argument. |
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2352 |
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2353 |
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2354 <h4 heading><a name="String.concat" href="#String.concat"><code>String.concat (···)</code></a></h4> |
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2355 |
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2356 <p> |
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2357 Concatenates the <a href="#Luan.to_string"><code>to_string</code></a> value of all arguments. |
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2358 |
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2359 |
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2360 |
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2361 <h4 heading><a name="String.encode" href="#String.encode"><code>String.encode (s)</code></a></h4> |
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2362 |
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2363 <p> |
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2364 Encodes argument <code>s</code> into a string that can be placed in quotes so as to return the original value of the string. |
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2365 |
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2366 |
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2367 |
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2368 |
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2369 <h4 heading><a name="String.find" href="#String.find"><code>String.find (s, pattern [, init [, plain]])</code></a></h4> |
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2370 |
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2371 <p> |
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2372 Looks for the first match of |
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2373 <code>pattern</code> (see <a href="http://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html">Pattern</a>) in the string <code>s</code>. |
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2374 If it finds a match, then <code>find</code> returns the indices of <code>s</code> |
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2375 where this occurrence starts and ends; |
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2376 otherwise, it returns <b>nil</b>. |
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2377 A third, optional numerical argument <code>init</code> specifies |
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2378 where to start the search; |
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2379 its default value is 1 and can be negative. |
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2380 A value of <b>true</b> as a fourth, optional argument <code>plain</code> |
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2381 turns off the pattern matching facilities, |
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2382 so the function does a plain "find substring" operation, |
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2383 with no characters in <code>pattern</code> being considered magic. |
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2384 Note that if <code>plain</code> is given, then <code>init</code> must be given as well. |
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2385 |
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2386 <p> |
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2387 If the pattern has captures, |
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2388 then in a successful match |
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2389 the captured values are also returned, |
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2390 after the two indices. |
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2391 |
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2392 |
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2393 |
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2394 |
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2395 <h4 heading><a name="String.format" href="#String.format"><code>String.format (formatstring, ···)</code></a></h4> |
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2396 |
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2397 |
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2398 <p> |
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2399 Returns a formatted version of its variable number of arguments |
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2400 following the description given in its first argument (which must be a string). |
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2401 The format string follows the same rules as the Java function <a href="http://docs.oracle.com/javase/7/docs/api/java/lang/String.html#format(java.lang.String,%20java.lang.Object...)"><code>String.format</code></a> because Luan calls this internally. |
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2402 |
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2403 <p> |
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2404 Note that Java's <code>String.format</code> is too stupid to convert between ints and floats, so you must provide the right kind of number. |
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2405 |
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2406 |
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2407 |
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2408 <h4 heading><a name="String.gmatch" href="#String.gmatch"><code>String.gmatch (s, pattern)</code></a></h4> |
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2409 |
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2410 <p> |
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2411 Returns an iterator function that, |
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2412 each time it is called, |
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2413 returns the next captures from <code>pattern</code> (see <a href="http://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html">Pattern</a>) |
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2414 over the string <code>s</code>. |
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2415 If <code>pattern</code> specifies no captures, |
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2416 then the whole match is produced in each call. |
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2417 |
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2418 |
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2419 <p> |
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2420 As an example, the following loop |
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2421 will iterate over all the words from string <code>s</code>, |
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2422 printing one per line: |
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2423 |
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2424 <pre> |
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2425 local s = "hello world from Lua" |
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2426 for w in String.gmatch(s, [[\w+]]) do |
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2427 print(w) |
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2428 end |
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2429 </pre> |
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2430 |
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2431 <p> |
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2432 The next example collects all pairs <code>key=value</code> from the |
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2433 given string into a table: |
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2434 |
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2435 <pre> |
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2436 local t = {} |
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2437 local s = "from=world, to=Lua" |
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2438 for k, v in String.gmatch(s, [[(\w+)=(\w+)]]) do |
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2439 t[k] = v |
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2440 end |
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2441 </pre> |
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2442 |
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2443 <p> |
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2444 For this function, a caret '<code>^</code>' at the start of a pattern does not |
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2445 work as an anchor, as this would prevent the iteration. |
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2446 |
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2447 |
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2448 |
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2449 <h4 heading><a name="String.gsub" href="#String.gsub"><code>String.gsub (s, pattern, repl [, n])</code></a></h4> |
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2450 |
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2451 <p> |
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2452 Returns a copy of <code>s</code> |
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2453 in which all (or the first <code>n</code>, if given) |
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2454 occurrences of the <code>pattern</code> (see <a href="http://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html">Pattern</a>) have been |
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2455 replaced by a replacement string specified by <code>repl</code>, |
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2456 which can be a string, a table, or a function. |
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2457 <code>gsub</code> also returns, as its second value, |
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2458 the total number of matches that occurred. |
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2459 The name <code>gsub</code> comes from <em>Global SUBstitution</em>. |
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2460 |
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2461 |
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2462 <p> |
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2463 If <code>repl</code> is a string, then its value is used for replacement. |
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2464 The character <code>\</code> works as an escape character. |
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2465 Any sequence in <code>repl</code> of the form <code>$<em>d</em></code>, |
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2466 with <em>d</em> between 1 and 9, |
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2467 stands for the value of the <em>d</em>-th captured substring. |
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2468 The sequence <code>$0</code> stands for the whole match. |
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2469 |
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2470 |
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2471 <p> |
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2472 If <code>repl</code> is a table, then the table is queried for every match, |
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2473 using the first capture as the key. |
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2474 |
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2475 |
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2476 <p> |
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2477 If <code>repl</code> is a function, then this function is called every time a |
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2478 match occurs, with all captured substrings passed as arguments, |
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2479 in order. |
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2480 |
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2481 |
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2482 <p> |
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2483 In any case, |
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2484 if the pattern specifies no captures, |
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2485 then it behaves as if the whole pattern was inside a capture. |
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2486 |
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|
2487 |
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2488 <p> |
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2489 If the value returned by the table query or by the function call |
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2490 is not <b>nil</b>, |
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2491 then it is used as the replacement string; |
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2492 otherwise, if it is <b>nil</b>, |
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2493 then there is no replacement |
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2494 (that is, the original match is kept in the string). |
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2495 |
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2496 |
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2497 <p> |
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2498 Here are some examples: |
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2499 |
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2500 <pre> |
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2501 x = String.gsub("hello world", [[(\w+)]], "$1 $1") |
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2502 --> x="hello hello world world" |
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2503 |
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2504 x = String.gsub("hello world", [[\w+]], "$0 $0", 1) |
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2505 --> x="hello hello world" |
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2506 |
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2507 x = String.gsub("hello world from Luan", [[(\w+)\s*(\w+)]], "$2 $1") |
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2508 --> x="world hello Luan from" |
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2509 |
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2510 x = String.gsub("4+5 = $return 4+5$", [[\$(.*?)\$]], function (s) |
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2511 return load(s)() |
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2512 end) |
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2513 --> x="4+5 = 9" |
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|
2514 |
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2515 local t = {name="lua", version="5.3"} |
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2516 x = String.gsub("$name-$version.tar.gz", [[\$(\w+)]], t) |
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2517 --> x="lua-5.3.tar.gz" |
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2518 </pre> |
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2519 |
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2520 |
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2521 |
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2522 <h4 heading><a name="String.literal" href="#String.literal"><code>String.literal (s)</code></a></h4> |
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2523 <p> |
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2524 Returns a string which matches the literal string <code>s</code> in a regular expression. This function is simply the Java method <a href="http://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html#quote(java.lang.String)"><code>Pattern.quote</code></a>. |
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2525 |
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2526 |
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2527 <h4 heading><a name="String.lower" href="#String.lower"><code>String.lower (s)</code></a></h4> |
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2528 <p> |
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2529 Receives a string and returns a copy of this string with all |
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2530 uppercase letters changed to lowercase. |
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2531 All other characters are left unchanged. |
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2532 |
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2533 |
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2534 |
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2535 |
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2536 <h4 heading><a name="String.match" href="#String.match"><code>String.match (s, pattern [, init])</code></a></h4> |
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2537 |
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2538 <p> |
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2539 Looks for the first <em>match</em> of |
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2540 <code>pattern</code> (see <a href="http://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html">Pattern</a>) in the string <code>s</code>. |
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2541 If it finds one, then <code>match</code> returns |
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2542 the captures from the pattern; |
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2543 otherwise it returns <b>nil</b>. |
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2544 If <code>pattern</code> specifies no captures, |
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2545 then the whole match is returned. |
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2546 A third, optional numerical argument <code>init</code> specifies |
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2547 where to start the search; |
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2548 its default value is 1 and can be negative. |
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2549 |
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2550 |
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2551 <h4 heading><a name="String.matches" href="#String.matches"><code>String.matches (s, pattern)</code></a></h4> |
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2552 <p> |
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2553 Returns a boolean indicating whether the <code>pattern</code> can be found in string <code>s</code>. |
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2554 This function is equivalent to |
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2555 |
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2556 <pre> |
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2557 return String.match(s,pattern) ~= nil |
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2558 </pre> |
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2559 |
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2560 |
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2561 <h4 heading><a name="String.rep" href="#String.rep"><code>String.rep (s, n [, sep])</code></a></h4> |
562
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2562 <p> |
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2563 Returns a string that is the concatenation of <code>n</code> copies of |
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2564 the string <code>s</code> separated by the string <code>sep</code>. |
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2565 The default value for <code>sep</code> is the empty string |
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2566 (that is, no separator). |
562
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2567 Returns the empty string if <code>n</code> is not positive. |
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2568 |
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2569 |
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2570 |
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2571 |
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2572 <h4 heading><a name="String.reverse" href="#String.reverse"><code>String.reverse (s)</code></a></h4> |
562
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2573 <p> |
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2574 Returns a string that is the string <code>s</code> reversed. |
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2575 |
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2576 |
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2577 |
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2578 |
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2579 <h4 heading><a name="String.sub" href="#String.sub"><code>String.sub (s, i [, j])</code></a></h4> |
562
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2580 |
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2581 <p> |
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2582 Returns the substring of <code>s</code> that |
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2583 starts at <code>i</code> and continues until <code>j</code>; |
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2584 <code>i</code> and <code>j</code> can be negative. |
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2585 If <code>j</code> is absent, then it is assumed to be equal to -1 |
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2586 (which is the same as the string length). |
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2587 In particular, |
562
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2588 the call <code>string.sub(s,1,j)</code> returns a prefix of <code>s</code> |
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2589 with length <code>j</code>, |
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2590 and <code>string.sub(s, -i)</code> returns a suffix of <code>s</code> |
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2591 with length <code>i</code>. |
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2592 |
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|
2593 |
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2594 <p> |
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2595 If, after the translation of negative indices, |
562
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2596 <code>i</code> is less than 1, |
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2597 it is corrected to 1. |
562
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2598 If <code>j</code> is greater than the string length, |
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2599 it is corrected to that length. |
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2600 If, after these corrections, |
562
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2601 <code>i</code> is greater than <code>j</code>, |
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2602 the function returns the empty string. |
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|
2603 |
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|
2604 |
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2605 |
642
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2606 <h4 heading><a name="String.to_binary" href="#String.to_binary"><code>String.to_binary (s)</code></a></h4> |
562
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2607 |
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2608 <p> |
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2609 Converts a string to a binary by calling the Java method <a href="http://docs.oracle.com/javase/7/docs/api/java/lang/String.html#getBytes()"><code>String.getBytes</code></a>. |
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2610 |
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|
2611 |
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2612 |
642
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2613 <h4 heading><a name="String.to_number" href="#String.to_number"><code>String.to_number (s [, base])</code></a></h4> |
562
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2614 |
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2615 <p> |
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2616 When called with no <code>base</code>, |
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2617 <code>to_number</code> tries to convert its argument to a number. |
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2618 If the argument is |
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2619 a string convertible to a number, |
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2620 then <code>to_number</code> returns this number; |
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2621 otherwise, it returns <b>nil</b>. |
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2622 |
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2623 The conversion of strings can result in integers or floats. |
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2624 |
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|
2625 |
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2626 <p> |
562
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2627 When called with <code>base</code>, |
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2628 then <code>s</code> must be a string to be interpreted as |
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2629 an integer numeral in that base. |
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2630 In bases above 10, the letter '<code>A</code>' (in either upper or lower case) |
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2631 represents 10, '<code>B</code>' represents 11, and so forth, |
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2632 with '<code>Z</code>' representing 35. |
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2633 If the string <code>s</code> is not a valid numeral in the given base, |
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2634 the function returns <b>nil</b>. |
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2635 |
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2636 |
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2637 |
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2638 <h4 heading><a name="String.trim" href="#String.trim"><code>String.trim (s)</code></a></h4> |
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2639 |
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2640 <p> |
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2641 Removes the leading and trailing whitespace by calling the Java method <a href="http://docs.oracle.com/javase/7/docs/api/java/lang/String.html#trim()"><code>String.trim</code></a>. |
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2642 |
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2643 |
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2644 |
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2645 |
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2646 <h4 heading><a name="String.unicode" href="#String.unicode"><code>String.unicode (s [, i [, j]])</code></a></h4> |
562
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2647 |
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2648 <p> |
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2649 Returns the internal numerical codes of the characters <code>s[i]</code>, |
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2650 <code>s[i+1]</code>, ..., <code>s[j]</code>. |
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2651 The default value for <code>i</code> is 1; |
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2652 the default value for <code>j</code> is <code>i</code>. |
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2653 These indices are corrected |
562
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2654 following the same rules of function <a href="#String.sub"><code>String.sub</code></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 <h4 heading><a name="String.upper" href="#String.upper"><code>String.upper (s)</code></a></h4> |
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2661 <p> |
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2662 Receives a string and returns a copy of this string with all |
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2663 lowercase letters changed to uppercase. |
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2664 All other characters are left unchanged. |
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2665 The definition of what a lowercase letter is depends on the current locale. |
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2666 |
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2667 |
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2668 |
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2669 |
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2670 |
567 | 2671 <h3 heading><a name="binary_lib">Binary Manipulation</a></h3> |
2672 | |
2673 <p> | |
2674 Include this library by: | |
2675 | |
2676 <pre> | |
2677 local Binary = require "luan:Binary" | |
2678 </pre> | |
2679 | |
2680 | |
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2681 <h4 heading><a name="Binary.binary" href="#Binary.binary"><code>Binary.binary (···)</code></a></h4> |
567 | 2682 |
2683 <p> | |
2684 Receives zero or more bytes (as integers). | |
2685 Returns a binary with length equal to the number of arguments, | |
2686 in which each byte has the internal numerical code equal | |
2687 to its corresponding argument. | |
2688 | |
2689 | |
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2690 <h4 heading><a name="Binary.byte" href="#Binary.byte"><code>Binary.byte (b [, i [, j]])</code></a></h4> |
567 | 2691 |
2692 <p> | |
2693 Returns the internal numerical codes of the bytes <code>b[i]</code>, | |
2694 <code>b[i+1]</code>, ..., <code>b[j]</code>. | |
2695 The default value for <code>i</code> is 1; | |
2696 the default value for <code>j</code> is <code>i</code>. | |
2697 These indices are corrected | |
2698 following the same rules of function <a href="#String.sub"><code>String.sub</code></a>. | |
2699 | |
2700 | |
642
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2701 <h4 heading><a name="Binary.to_string" href="#Binary.to_string"><code>Binary.to_string (b)</code></a></h4> |
567 | 2702 <p> |
2703 Converts the binary <code>b</code> to a string using the Java <a href="http://docs.oracle.com/javase/7/docs/api/java/lang/String.html#String(byte[])">String constructor</a>. | |
2704 | |
371
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2705 |
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2706 |
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2707 |
565
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2708 <h3 heading><a name="table_lib">Table Manipulation</a></h3> |
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2709 |
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2710 <p> |
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2711 Include this library by: |
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2712 |
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2713 <pre> |
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2714 local Table = require "luan:Table" |
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2715 </pre> |
371
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2716 |
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2717 <p> |
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2718 This library provides generic functions for table manipulation. |
565
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2719 It provides all its functions inside the table <code>Table</code>. |
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2720 |
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2721 |
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2722 |
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2723 <h4 heading><a name="Table.clear" href="#Table.clear"><code>Table.clear (tbl)</code></a></h4> |
580 | 2724 |
2725 <p> | |
2726 Clears the table. | |
2727 | |
2728 | |
642
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2729 <h4 heading><a name="Table.concat" href="#Table.concat"><code>Table.concat (list [, sep [, i [, j]]])</code></a></h4> |
565
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2730 |
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2731 <p> |
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2732 Given a list, |
371
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2733 returns the string <code>list[i]..sep..list[i+1] ··· sep..list[j]</code>. |
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2734 The default value for <code>sep</code> is the empty string, |
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2735 the default for <code>i</code> is 1, |
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2736 and the default for <code>j</code> is <code>#list</code>. |
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2737 If <code>i</code> is greater than <code>j</code>, returns the empty string. |
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2738 |
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2739 |
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2740 <h4 heading><a name="Table.copy" href="#Table.copy"><code>Table.copy (tbl [, i [, j]])</code></a></h4> |
565
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2741 |
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2742 <p> |
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2743 If <code>i</code> is <code>nil</code>, returns a shallow copy of <code>tbl</code>. |
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2744 Otherwise returns a new table which is a list of the elements <code>tbl[i] ··· tbl[j]</code>. |
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2745 By default, <code>j</code> is <code>#tbl</code>. |
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2746 |
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2747 |
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2748 |
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2749 <h4 heading><a name="Table.insert" href="#Table.insert"><code>Table.insert (list, pos, value)</code></a></h4> |
371
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2750 |
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2751 <p> |
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2752 Inserts element <code>value</code> at position <code>pos</code> in <code>list</code>, |
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2753 shifting up the elements |
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2754 <code>list[pos], list[pos+1], ···, list[#list]</code>. |
565
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2755 |
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2756 |
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2757 |
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2758 <h4 heading><a name="Table.pack" href="#Table.pack"><code>Table.pack (···)</code></a></h4> |
371
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2759 |
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2760 <p> |
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2761 Returns a new table with all parameters stored into keys 1, 2, etc. |
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2762 and with a field "<code>n</code>" with the total number of parameters. |
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2763 Note that the resulting table may not be a sequence. |
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2764 |
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2765 |
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2766 |
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2767 |
642
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2768 <h4 heading><a name="Table.remove" href="#Table.remove"><code>Table.remove (list, pos)</code></a></h4> |
371
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2769 |
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|
2770 |
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2771 <p> |
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2772 Removes from <code>list</code> the element at position <code>pos</code>, |
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2773 returning the value of the removed element. |
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2774 When <code>pos</code> is an integer between 1 and <code>#list</code>, |
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2775 it shifts down the elements |
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2776 <code>list[pos+1], list[pos+2], ···, list[#list]</code> |
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2777 and erases element <code>list[#list]</code>; |
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2778 The index <code>pos</code> can also be 0 when <code>#list</code> is 0, |
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2779 or <code>#list + 1</code>; |
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2780 in those cases, the function erases the element <code>list[pos]</code>. |
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2781 |
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2782 |
565
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2783 |
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2784 |
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2785 <h4 heading><a name="Table.sort" href="#Table.sort"><code>Table.sort (list [, comp])</code></a></h4> |
371
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2786 |
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2787 <p> |
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2788 Sorts list elements in a given order, <em>in-place</em>, |
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2789 from <code>list[1]</code> to <code>list[#list]</code>. |
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2790 If <code>comp</code> is given, |
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2791 then it must be a function that receives two list elements |
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2792 and returns true when the first element must come |
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2793 before the second in the final order |
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2794 (so that <code>not comp(list[i+1],list[i])</code> will be true after the sort). |
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2795 If <code>comp</code> is not given, |
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2796 then the standard Lua operator <code><</code> is used instead. |
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2797 |
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2798 <p> |
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2799 The sort algorithm is not stable; |
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2800 that is, elements considered equal by the given order |
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2801 may have their relative positions changed by the sort. |
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2802 |
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2803 |
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2804 |
642
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2805 <h4 heading><a name="Table.unpack" href="#Table.unpack"><code>Table.unpack (list [, i [, j]])</code></a></h4> |
371
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2806 |
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2807 <p> |
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2808 Returns the elements from the given list. |
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2809 This function is equivalent to |
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2810 |
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2811 <pre> |
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2812 return list[i], list[i+1], ···, list[j] |
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2813 </pre> |
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|
2814 |
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|
2815 <p> |
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2816 By default, <code>i</code> is 1 and <code>j</code> is <code>#list</code>. |
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|
2817 |
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diff
changeset
|
2818 |
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diff
changeset
|
2819 |
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diff
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|
2820 |
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|
2821 <h3 heading><a name="number_lib">Number Manipulation</a></h3> |
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2822 |
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|
2823 <p> |
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diff
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|
2824 Include this library by: |
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|
2825 |
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Number and Math documentation and minor changes
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|
2826 <pre> |
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|
2827 local Number = require "luan:Number" |
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|
2828 </pre> |
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diff
changeset
|
2829 |
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Number and Math documentation and minor changes
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|
2830 |
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2831 <h4 heading><a name="Number.double" href="#Number.double"><code>Number.double (x)</code></a></h4> |
566
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|
2832 <p> |
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|
2833 Returns <code>x</code> as a double. |
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Number and Math documentation and minor changes
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|
2834 |
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|
2835 |
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2836 <h4 heading><a name="Number.integer" href="#Number.integer"><code>Number.integer (x)</code></a></h4> |
566
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|
2837 <p> |
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2838 If the value <code>x</code> is convertible to an integer, |
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2839 returns that integer. |
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Number and Math documentation and minor changes
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|
2840 Otherwise throws an error. |
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Number and Math documentation and minor changes
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|
2841 |
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|
2842 |
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|
2843 <h4 heading><a name="Number.long" href="#Number.long"><code>Number.long (x)</code></a></h4> |
566
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|
2844 <p> |
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|
2845 If the value <code>x</code> is convertible to an long, |
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diff
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|
2846 returns that long. |
90b93790c544
Number and Math documentation and minor changes
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parents:
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diff
changeset
|
2847 Otherwise throws an error. |
90b93790c544
Number and Math documentation and minor changes
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565
diff
changeset
|
2848 |
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|
2849 |
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|
2850 <h4 heading><a name="Number.long_to_string" href="#Number.long_to_string"><code>Number.long_to_string (i, radix)</code></a></h4> |
566
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|
2851 <p> |
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|
2852 Converts long value <code>i</code> to a string by calling <code><a href="http://docs.oracle.com/javase/7/docs/api/java/lang/Long.html#toString(long,%20int)">Long.toString</a></code>. |
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|
2853 |
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|
2854 |
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|
2855 <h4 heading><a name="Number.type" href="#Number.type"><code>Number.type (x)</code></a></h4> |
566
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|
2856 <p> |
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|
2857 Returns a string for the numeric type of <code>x</code>. Possible return values include "<code>integer</code>", "<code>long</code>", "<code>double</code>", and "<code>float</code>". |
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|
2858 |
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565
diff
changeset
|
2859 |
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Number and Math documentation and minor changes
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565
diff
changeset
|
2860 |
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Number and Math documentation and minor changes
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diff
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|
2861 |
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|
2862 <h3 heading><a name="math_lib">Mathematical Functions</a></h3> |
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|
2863 |
90b93790c544
Number and Math documentation and minor changes
Franklin Schmidt <fschmidt@gmail.com>
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565
diff
changeset
|
2864 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
2865 Include this library by: |
90b93790c544
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Franklin Schmidt <fschmidt@gmail.com>
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565
diff
changeset
|
2866 |
90b93790c544
Number and Math documentation and minor changes
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565
diff
changeset
|
2867 <pre> |
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diff
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|
2868 local Math = require "luan:Math" |
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|
2869 </pre> |
371
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|
2870 |
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diff
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|
2871 <p> |
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diff
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|
2872 This library provides basic mathematical functions. |
566
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diff
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|
2873 It provides all its functions and constants inside the table <code>Math</code>. |
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|
2874 |
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diff
changeset
|
2875 |
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|
2876 <h4 heading><a name="Math.abs" href="#Math.abs"><code>Math.abs (x)</code></a></h4> |
566
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diff
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|
2877 |
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diff
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|
2878 <p> |
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diff
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|
2879 Returns the absolute value of <code>x</code>. |
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diff
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|
2880 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
565
diff
changeset
|
2881 |
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565
diff
changeset
|
2882 |
642
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|
2883 <h4 heading><a name="Math.acos" href="#Math.acos"><code>Math.acos (x)</code></a></h4> |
371
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|
2884 |
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|
2885 <p> |
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|
2886 Returns the arc cosine of <code>x</code> (in radians). |
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diff
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|
2887 |
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parents:
diff
changeset
|
2888 |
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parents:
diff
changeset
|
2889 |
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diff
changeset
|
2890 |
642
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diff
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|
2891 <h4 heading><a name="Math.asin" href="#Math.asin"><code>Math.asin (x)</code></a></h4> |
371
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|
2892 |
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diff
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|
2893 <p> |
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|
2894 Returns the arc sine of <code>x</code> (in radians). |
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|
2895 |
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diff
changeset
|
2896 |
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diff
changeset
|
2897 |
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parents:
diff
changeset
|
2898 |
642
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629
diff
changeset
|
2899 <h4 heading><a name="Math.atan" href="#Math.atan"><code>Math.atan (y, x)</code></a></h4> |
566
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diff
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|
2900 |
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|
2901 <p> |
371
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|
2902 Returns the arc tangent of <code>y/x</code> (in radians), |
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|
2903 but uses the signs of both parameters to find the |
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|
2904 quadrant of the result. |
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diff
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|
2905 (It also handles correctly the case of <code>x</code> being zero.) |
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|
2906 |
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changeset
|
2907 |
566
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changeset
|
2908 |
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|
2909 |
642
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|
2910 <h4 heading><a name="Math.ceil" href="#Math.ceil"><code>Math.ceil (x)</code></a></h4> |
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|
2911 |
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|
2912 <p> |
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|
2913 Returns the smallest integral value larger than or equal to <code>x</code>. |
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|
2914 |
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|
2915 |
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|
2916 |
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|
2917 |
642
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|
2918 <h4 heading><a name="Math.cos" href="#Math.cos"><code>Math.cos (x)</code></a></h4> |
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|
2919 |
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|
2920 <p> |
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|
2921 Returns the cosine of <code>x</code> (assumed to be in radians). |
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|
2922 |
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|
2923 |
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|
2924 |
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|
2925 |
642
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|
2926 <h4 heading><a name="Math.deg" href="#Math.deg"><code>Math.deg (x)</code></a></h4> |
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|
2927 |
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|
2928 <p> |
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|
2929 Converts the angle <code>x</code> from radians to degrees. |
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|
2930 |
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|
2931 |
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|
2932 |
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|
2933 |
642
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|
2934 <h4 heading><a name="Math.exp" href="#Math.exp"><code>Math.exp (x)</code></a></h4> |
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|
2935 |
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|
2936 <p> |
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|
2937 Returns the value <em>e<sup>x</sup></em> |
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|
2938 (where <code>e</code> is the base of natural logarithms). |
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|
2939 |
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changeset
|
2940 |
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|
2941 |
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2942 |
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2943 <h4 heading><a name="Math.floor" href="#Math.floor"><code>Math.floor (x)</code></a></h4> |
371
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2944 |
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|
2945 <p> |
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2946 Returns the largest integral value smaller than or equal to <code>x</code>. |
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|
2947 |
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|
2948 |
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|
2949 |
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|
2950 |
642
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2951 <h4 heading><a name="Math.fmod" href="#Math.fmod"><code>Math.fmod (x, y)</code></a></h4> |
371
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2952 |
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|
2953 <p> |
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2954 Returns the remainder of the division of <code>x</code> by <code>y</code> |
566
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2955 that rounds the quotient towards zero. |
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2956 |
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|
2957 |
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Number and Math documentation and minor changes
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|
2958 |
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2959 |
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2960 <h4 heading><a name="Math.huge" href="#Math.huge"><code>Math.huge</code></a></h4> |
566
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2961 |
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2962 <p> |
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2963 A value larger than any other numerical value. |
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2964 |
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|
2965 |
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Number and Math documentation and minor changes
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|
2966 |
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2967 |
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2968 <h4 heading><a name="Math.log" href="#Math.log"><code>Math.log (x [, base])</code></a></h4> |
371
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2969 |
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2970 <p> |
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2971 Returns the logarithm of <code>x</code> in the given base. |
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2972 The default for <code>base</code> is <em>e</em> |
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2973 (so that the function returns the natural logarithm of <code>x</code>). |
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|
2974 |
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|
2975 |
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|
2976 |
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|
2977 |
642
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2978 <h4 heading><a name="Math.max" href="#Math.max"><code>Math.max (x, ···)</code></a></h4> |
371
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|
2979 |
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|
2980 <p> |
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2981 Returns the argument with the maximum value, |
566
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2982 according to the Lua operator <code><</code>. |
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|
2983 |
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565
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|
2984 |
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Number and Math documentation and minor changes
Franklin Schmidt <fschmidt@gmail.com>
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565
diff
changeset
|
2985 |
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|
2986 |
642
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|
2987 <h4 heading><a name="Math.max_integer" href="#Math.max_integer"><code>Math.max_integer</code></a></h4> |
566
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2988 <p> |
371
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2989 An integer with the maximum value for an integer. |
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|
2990 |
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|
2991 |
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|
2992 |
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|
2993 |
642
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2994 <h4 heading><a name="Math.min" href="#Math.min"><code>Math.min (x, ···)</code></a></h4> |
371
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|
2995 |
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|
2996 <p> |
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|
2997 Returns the argument with the minimum value, |
566
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2998 according to the Lua operator <code><</code>. |
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|
2999 |
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|
3000 |
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|
3001 |
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|
3002 |
642
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|
3003 <h4 heading><a name="Math.min_integer" href="#Math.min_integer"><code>Math.min_integer</code></a></h4> |
566
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3004 <p> |
371
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|
3005 An integer with the minimum value for an integer. |
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|
3006 |
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|
3007 |
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|
3008 |
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|
3009 |
642
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|
3010 <h4 heading><a name="Math.modf" href="#Math.modf"><code>Math.modf (x)</code></a></h4> |
371
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|
3011 |
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|
3012 <p> |
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|
3013 Returns the integral part of <code>x</code> and the fractional part of <code>x</code>. |
566
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|
3014 |
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565
diff
changeset
|
3015 |
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Number and Math documentation and minor changes
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diff
changeset
|
3016 |
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|
3017 |
642
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|
3018 <h4 heading><a name="Math.pi" href="#Math.pi"><code>Math.pi</code></a></h4> |
371
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|
3019 |
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|
3020 <p> |
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|
3021 The value of <em>π</em>. |
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|
3022 |
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|
3023 |
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changeset
|
3024 |
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|
3025 |
642
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|
3026 <h4 heading><a name="Math.rad" href="#Math.rad"><code>Math.rad (x)</code></a></h4> |
371
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|
3027 |
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|
3028 <p> |
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|
3029 Converts the angle <code>x</code> from degrees to radians. |
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|
3030 |
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diff
changeset
|
3031 |
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diff
changeset
|
3032 |
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|
3033 |
642
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|
3034 <h4 heading><a name="Math.random" href="#Math.random"><code>Math.random ([m [, n])</code></a></h4> |
371
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|
3035 |
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changeset
|
3036 |
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|
3037 <p> |
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|
3038 When called without arguments, |
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|
3039 returns a pseudo-random float with uniform distribution |
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|
3040 in the range <em>[0,1)</em>. |
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|
3041 When called with two integers <code>m</code> and <code>n</code>, |
566
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3042 <code>Math.random</code> returns a pseudo-random integer |
371
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|
3043 with uniform distribution in the range <em>[m, n]</em>. |
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3044 (The value <em>m-n</em> cannot be negative and must fit in a Luan integer.) |
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3045 The call <code>Math.random(n)</code> is equivalent to <code>Math.random(1,n)</code>. |
371
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|
3046 |
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|
3047 |
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|
3048 <p> |
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|
3049 This function is an interface to the underling |
566
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3050 pseudo-random generator function provided by Java. |
371
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|
3051 No guarantees can be given for its statistical properties. |
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|
3052 |
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|
3053 |
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|
3054 |
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|
3055 |
642
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3056 <h4 heading><a name="Math.sin" href="#Math.sin"><code>Math.sin (x)</code></a></h4> |
371
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|
3057 |
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changeset
|
3058 <p> |
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|
3059 Returns the sine of <code>x</code> (assumed to be in radians). |
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|
3060 |
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changeset
|
3061 |
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diff
changeset
|
3062 |
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changeset
|
3063 |
642
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3064 <h4 heading><a name="Math.sqrt" href="#Math.sqrt"><code>Math.sqrt (x)</code></a></h4> |
371
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|
3065 |
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changeset
|
3066 <p> |
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|
3067 Returns the square root of <code>x</code>. |
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3068 (You can also use the expression <code>x^0.5</code> to compute this value.) |
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3069 |
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|
3070 |
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|
3071 |
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|
3072 |
642
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3073 <h4 heading><a name="Math.tan" href="#Math.tan"><code>Math.tan (x)</code></a></h4> |
371
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3074 |
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3075 <p> |
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|
3076 Returns the tangent of <code>x</code> (assumed to be in radians). |
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3077 |
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|
3078 |
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diff
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|
3079 |
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diff
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|
3080 |
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3081 |
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3082 |
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3083 |
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3084 |
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3085 <h2>6.8 – <a name="6.8">Input and Output Facilities</a></h2> |
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3086 |
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3087 <p> |
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3088 The I/O library provides two different styles for file manipulation. |
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3089 The first one uses implicit file handles; |
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3090 that is, there are operations to set a default input file and a |
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3091 default output file, |
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3092 and all input/output operations are over these default files. |
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3093 The second style uses explicit file handles. |
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3094 |
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3095 |
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3096 <p> |
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3097 When using implicit file handles, |
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3098 all operations are supplied by table <a name="pdf-io"><code>io</code></a>. |
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3099 When using explicit file handles, |
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|
3100 the operation <a href="#pdf-io.open"><code>io.open</code></a> returns a file handle |
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3101 and then all operations are supplied as methods of the file handle. |
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3102 |
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|
3103 |
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3104 <p> |
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3105 The table <code>io</code> also provides |
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3106 three predefined file handles with their usual meanings from C: |
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3107 <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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|
3108 The I/O library never closes these files. |
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3109 |
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3110 |
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3111 <p> |
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|
3112 Unless otherwise stated, |
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3113 all I/O functions return <b>nil</b> on failure |
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3114 (plus an error message as a second result and |
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3115 a system-dependent error code as a third result) |
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3116 and some value different from <b>nil</b> on success. |
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3117 On non-POSIX systems, |
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3118 the computation of the error message and error code |
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|
3119 in case of errors |
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|
3120 may be not thread safe, |
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|
3121 because they rely on the global C variable <code>errno</code>. |
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|
3122 |
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|
3123 |
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3124 <p> |
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|
3125 <hr><h3><a name="pdf-io.close"><code>io.close ([file])</code></a></h3> |
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|
3126 |
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|
3127 |
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3128 <p> |
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|
3129 Equivalent to <code>file:close()</code>. |
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3130 Without a <code>file</code>, closes the default output file. |
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|
3131 |
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|
3132 |
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3133 |
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|
3134 |
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3135 <p> |
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|
3136 <hr><h3><a name="pdf-io.flush"><code>io.flush ()</code></a></h3> |
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|
3137 |
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|
3138 |
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|
3139 <p> |
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|
3140 Equivalent to <code>io.output():flush()</code>. |
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|
3141 |
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diff
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|
3142 |
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|
3143 |
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|
3144 |
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|
3145 <p> |
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|
3146 <hr><h3><a name="pdf-io.input"><code>io.input ([file])</code></a></h3> |
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|
3147 |
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|
3148 |
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|
3149 <p> |
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|
3150 When called with a file name, it opens the named file (in text mode), |
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|
3151 and sets its handle as the default input file. |
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|
3152 When called with a file handle, |
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|
3153 it simply sets this file handle as the default input file. |
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|
3154 When called without parameters, |
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|
3155 it returns the current default input file. |
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|
3156 |
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|
3157 |
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|
3158 <p> |
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|
3159 In case of errors this function raises the error, |
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|
3160 instead of returning an error code. |
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|
3161 |
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|
3162 |
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3163 |
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3164 |
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3165 <p> |
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|
3166 <hr><h3><a name="pdf-io.lines"><code>io.lines ([filename ···])</code></a></h3> |
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3167 |
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3168 |
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3169 <p> |
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3170 Opens the given file name in read mode |
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3171 and returns an iterator function that |
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3172 works like <code>file:lines(···)</code> over the opened file. |
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3173 When the iterator function detects the end of file, |
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3174 it returns no values (to finish the loop) and automatically closes the file. |
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3175 |
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|
3176 |
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3177 <p> |
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3178 The call <code>io.lines()</code> (with no file name) is equivalent |
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3179 to <code>io.input():lines("*l")</code>; |
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3180 that is, it iterates over the lines of the default input file. |
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3181 In this case it does not close the file when the loop ends. |
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|
3182 |
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|
3183 |
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3184 <p> |
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3185 In case of errors this function raises the error, |
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3186 instead of returning an error code. |
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3187 |
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3188 |
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|
3189 |
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3190 |
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3191 <p> |
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|
3192 <hr><h3><a name="pdf-io.open"><code>io.open (filename [, mode])</code></a></h3> |
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parents:
diff
changeset
|
3193 |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3194 |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
3195 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3196 This function opens a file, |
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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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|
3197 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
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|
3198 It returns a new file handle, |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
3199 or, in case of errors, <b>nil</b> plus an error message. |
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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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|
3200 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3201 |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3202 <p> |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
3203 The <code>mode</code> string can be any of the following: |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3204 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3205 <ul> |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
3206 <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
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parents:
diff
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|
3207 <li><b>"<code>w</code>": </b> write mode;</li> |
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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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|
3208 <li><b>"<code>a</code>": </b> append mode;</li> |
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add manual.html as copy of Lua 5.3 Reference Manual
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parents:
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|
3209 <li><b>"<code>r+</code>": </b> update mode, all previous data is preserved;</li> |
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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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|
3210 <li><b>"<code>w+</code>": </b> update mode, all previous data is erased;</li> |
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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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|
3211 <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>
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|
3212 writing is only allowed at the end of file.</li> |
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diff
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|
3213 </ul><p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3214 The <code>mode</code> string can also have a '<code>b</code>' at the end, |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3215 which is needed in some systems to open the file in binary mode. |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3216 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3217 |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3218 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3219 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3220 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
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|
3221 <hr><h3><a name="pdf-io.output"><code>io.output ([file])</code></a></h3> |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3222 |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3223 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3224 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3225 Similar to <a href="#pdf-io.input"><code>io.input</code></a>, but operates over the default output file. |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3226 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3227 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3228 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3229 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3230 <p> |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3231 <hr><h3><a name="pdf-io.popen"><code>io.popen (prog [, mode])</code></a></h3> |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
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diff
changeset
|
3232 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3233 |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3234 <p> |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3235 This function is system dependent and is not available |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3236 on all platforms. |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3237 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3238 |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3239 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3240 Starts program <code>prog</code> in a separated process and returns |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3241 a file handle that you can use to read data from this program |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3242 (if <code>mode</code> is <code>"r"</code>, the default) |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3243 or to write data to this program |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3244 (if <code>mode</code> is <code>"w"</code>). |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3245 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3246 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3247 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3248 |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3249 <p> |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
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|
3250 <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
|
3251 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3252 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3253 <p> |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3254 Equivalent to <code>io.input():read(···)</code>. |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3255 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3256 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3257 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3258 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3259 <p> |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3260 <hr><h3><a name="pdf-io.tmpfile"><code>io.tmpfile ()</code></a></h3> |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3261 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3262 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3263 <p> |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3264 Returns a handle for a temporary file. |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3265 This file is opened in update mode |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3266 and it is automatically removed when the program ends. |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3267 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3268 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3269 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3270 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3271 <p> |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3272 <hr><h3><a name="pdf-io.type"><code>io.type (obj)</code></a></h3> |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3273 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3274 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3275 <p> |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3276 Checks whether <code>obj</code> is a valid file handle. |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3277 Returns the string <code>"file"</code> if <code>obj</code> is an open file handle, |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3278 <code>"closed file"</code> if <code>obj</code> is a closed file handle, |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3279 or <b>nil</b> if <code>obj</code> is not a file handle. |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3280 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3281 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3282 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3283 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3284 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3285 <hr><h3><a name="pdf-io.write"><code>io.write (···)</code></a></h3> |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3286 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3287 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3288 <p> |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3289 Equivalent to <code>io.output():write(···)</code>. |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3290 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3291 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3292 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3293 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3294 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3295 <hr><h3><a name="pdf-file:close"><code>file:close ()</code></a></h3> |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3296 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3297 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3298 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3299 Closes <code>file</code>. |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3300 Note that files are automatically closed when |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3301 their handles are garbage collected, |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3302 but that takes an unpredictable amount of time to happen. |
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add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3303 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3304 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3305 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3306 When closing a file handle created with <a href="#pdf-io.popen"><code>io.popen</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
|
3307 <a href="#pdf-file:close"><code>file:close</code></a> returns the same values |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3308 returned by <a href="#pdf-os.execute"><code>os.execute</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
|
3309 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3310 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3311 |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3312 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3313 <p> |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3314 <hr><h3><a name="pdf-file:flush"><code>file:flush ()</code></a></h3> |
e01cddba3433
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3315 |
e01cddba3433
add manual.html as copy of Lua 5.3 Reference Manual
Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3316 |
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Franklin Schmidt <fschmidt@gmail.com>
parents:
diff
changeset
|
3317 <p> |
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|
3318 Saves any written data to <code>file</code>. |
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|
3319 |
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diff
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|
3320 |
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diff
changeset
|
3321 |
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diff
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|
3322 |
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|
3323 <p> |
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|
3324 <hr><h3><a name="pdf-file:lines"><code>file:lines (···)</code></a></h3> |
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|
3325 |
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|
3326 |
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|
3327 <p> |
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|
3328 Returns an iterator function that, |
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|
3329 each time it is called, |
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|
3330 reads the file according to the given formats. |
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|
3331 When no format is given, |
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|
3332 uses "<code>l</code>" as a default. |
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|
3333 As an example, the construction |
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|
3334 |
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|
3335 <pre> |
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|
3336 for c in file:lines(1) do <em>body</em> end |
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|
3337 </pre><p> |
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|
3338 will iterate over all characters of the file, |
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|
3339 starting at the current position. |
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|
3340 Unlike <a href="#pdf-io.lines"><code>io.lines</code></a>, this function does not close the file |
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|
3341 when the loop ends. |
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|
3342 |
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|
3343 |
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|
3344 <p> |
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|
3345 In case of errors this function raises the error, |
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|
3346 instead of returning an error code. |
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|
3347 |
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|
3348 |
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diff
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|
3349 |
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|
3350 |
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|
3351 <p> |
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|
3352 <hr><h3><a name="pdf-file:read"><code>file:read (···)</code></a></h3> |
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|
3353 |
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|
3354 |
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|
3355 <p> |
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|
3356 Reads the file <code>file</code>, |
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|
3357 according to the given formats, which specify what to read. |
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|
3358 For each format, |
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|
3359 the function returns a string or a number with the characters read, |
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|
3360 or <b>nil</b> if it cannot read data with the specified format. |
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|
3361 (In this latter case, |
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diff
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|
3362 the function does not read subsequent formats.) |
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|
3363 When called without formats, |
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|
3364 it uses a default format that reads the next line |
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|
3365 (see below). |
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|
3366 |
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|
3367 |
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|
3368 <p> |
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|
3369 The available formats are |
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|
3370 |
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|
3371 <ul> |
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|
3372 |
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|
3373 <li><b>"<code>n</code>": </b> |
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|
3374 reads a numeral and returns it as a float or an integer, |
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|
3375 following the lexical conventions of Lua. |
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diff
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|
3376 (The numeral may have leading spaces and a sign.) |
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diff
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|
3377 This format always reads the longest input sequence that |
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diff
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|
3378 is a valid prefix for a number; |
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parents:
diff
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|
3379 if that prefix does not form a valid number |
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diff
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|
3380 (e.g., an empty string, "<code>0x</code>", or "<code>3.4e-</code>"), |
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diff
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|
3381 it is discarded and the function returns <b>nil</b>. |
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|
3382 </li> |
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diff
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|
3383 |
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|
3384 <li><b>"<code>i</code>": </b> |
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|
3385 reads an integral number and returns it as an integer. |
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|
3386 </li> |
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diff
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|
3387 |
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diff
changeset
|
3388 <li><b>"<code>a</code>": </b> |
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|
3389 reads the whole file, starting at the current position. |
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parents:
diff
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|
3390 On end of file, it returns the empty string. |
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|
3391 </li> |
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diff
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|
3392 |
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|
3393 <li><b>"<code>l</code>": </b> |
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diff
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|
3394 reads the next line skipping the end of line, |
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diff
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|
3395 returning <b>nil</b> on end of file. |
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|
3396 This is the default format. |
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parents:
diff
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|
3397 </li> |
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Franklin Schmidt <fschmidt@gmail.com>
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diff
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|
3398 |
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diff
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|
3399 <li><b>"<code>L</code>": </b> |
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diff
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|
3400 reads the next line keeping the end-of-line character (if present), |
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parents:
diff
changeset
|
3401 returning <b>nil</b> on end of file. |
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diff
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|
3402 </li> |
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diff
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|
3403 |
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|
3404 <li><b><em>number</em>: </b> |
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|
3405 reads a string with up to this number of bytes, |
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diff
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|
3406 returning <b>nil</b> on end of file. |
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changeset
|
3407 If <code>number</code> is zero, |
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|
3408 it reads nothing and returns an empty string, |
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diff
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|
3409 or <b>nil</b> on end of file. |
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diff
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|
3410 </li> |
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diff
changeset
|
3411 |
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diff
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|
3412 </ul><p> |
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|
3413 The formats "<code>l</code>" and "<code>L</code>" should be used only for text files. |
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|
3414 |
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changeset
|
3415 |
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diff
changeset
|
3416 |
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changeset
|
3417 |
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|
3418 <p> |
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|
3419 <hr><h3><a name="pdf-file:seek"><code>file:seek ([whence [, offset]])</code></a></h3> |
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|
3420 |
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diff
changeset
|
3421 |
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changeset
|
3422 <p> |
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|
3423 Sets and gets the file position, |
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changeset
|
3424 measured from the beginning of the file, |
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diff
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|
3425 to the position given by <code>offset</code> plus a base |
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|
3426 specified by the string <code>whence</code>, as follows: |
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|
3427 |
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changeset
|
3428 <ul> |
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|
3429 <li><b>"<code>set</code>": </b> base is position 0 (beginning of the file);</li> |
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|
3430 <li><b>"<code>cur</code>": </b> base is current position;</li> |
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|
3431 <li><b>"<code>end</code>": </b> base is end of file;</li> |
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|
3432 </ul><p> |
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|
3433 In case of success, <code>seek</code> returns the final file position, |
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|
3434 measured in bytes from the beginning of the file. |
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|
3435 If <code>seek</code> fails, it returns <b>nil</b>, |
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changeset
|
3436 plus a string describing the error. |
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changeset
|
3437 |
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|
3438 |
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changeset
|
3439 <p> |
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|
3440 The default value for <code>whence</code> is <code>"cur"</code>, |
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|
3441 and for <code>offset</code> is 0. |
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3442 Therefore, the call <code>file:seek()</code> returns the current |
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3443 file position, without changing it; |
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3444 the call <code>file:seek("set")</code> sets the position to the |
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|
3445 beginning of the file (and returns 0); |
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|
3446 and the call <code>file:seek("end")</code> sets the position to the |
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|
3447 end of the file, and returns its size. |
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|
3448 |
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|
3449 |
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diff
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|
3450 |
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|
3451 |
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|
3452 <p> |
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|
3453 <hr><h3><a name="pdf-file:setvbuf"><code>file:setvbuf (mode [, size])</code></a></h3> |
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|
3454 |
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|
3455 |
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|
3456 <p> |
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3457 Sets the buffering mode for an output file. |
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3458 There are three available modes: |
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|
3459 |
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|
3460 <ul> |
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|
3461 |
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|
3462 <li><b>"<code>no</code>": </b> |
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3463 no buffering; the result of any output operation appears immediately. |
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3464 </li> |
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|
3465 |
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|
3466 <li><b>"<code>full</code>": </b> |
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|
3467 full buffering; output operation is performed only |
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3468 when the buffer is full or when |
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|
3469 you explicitly <code>flush</code> the file (see <a href="#pdf-io.flush"><code>io.flush</code></a>). |
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3470 </li> |
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|
3471 |
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3472 <li><b>"<code>line</code>": </b> |
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3473 line buffering; output is buffered until a newline is output |
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3474 or there is any input from some special files |
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3475 (such as a terminal device). |
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|
3476 </li> |
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|
3477 |
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|
3478 </ul><p> |
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|
3479 For the last two cases, <code>size</code> |
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|
3480 specifies the size of the buffer, in bytes. |
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|
3481 The default is an appropriate size. |
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|
3482 |
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|
3483 |
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|
3484 |
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diff
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|
3485 |
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|
3486 <p> |
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|
3487 <hr><h3><a name="pdf-file:write"><code>file:write (···)</code></a></h3> |
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|
3488 |
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diff
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|
3489 |
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diff
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|
3490 <p> |
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|
3491 Writes the value of each of its arguments to <code>file</code>. |
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|
3492 The arguments must be strings or numbers. |
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|
3493 |
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|
3494 |
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|
3495 <p> |
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|
3496 In case of success, this function returns <code>file</code>. |
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|
3497 Otherwise it returns <b>nil</b> plus a string describing the error. |
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|
3498 |
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diff
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|
3499 |
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|
3500 |
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|
3501 |
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|
3502 |
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|
3503 |
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|
3504 |
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|
3505 <h2>6.9 – <a name="6.9">Operating System Facilities</a></h2> |
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|
3506 |
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|
3507 <p> |
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|
3508 This library is implemented through table <a name="pdf-os"><code>os</code></a>. |
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|
3509 |
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|
3510 |
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|
3511 <p> |
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|
3512 <hr><h3><a name="pdf-os.clock"><code>os.clock ()</code></a></h3> |
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|
3513 |
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diff
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|
3514 |
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|
3515 <p> |
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|
3516 Returns an approximation of the amount in seconds of CPU time |
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|
3517 used by the program. |
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|
3518 |
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diff
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|
3519 |
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diff
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|
3520 |
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diff
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|
3521 |
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|
3522 <p> |
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|
3523 <hr><h3><a name="pdf-os.date"><code>os.date ([format [, time]])</code></a></h3> |
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|
3524 |
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|
3525 |
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|
3526 <p> |
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|
3527 Returns a string or a table containing date and time, |
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|
3528 formatted according to the given string <code>format</code>. |
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|
3529 |
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|
3530 |
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|
3531 <p> |
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|
3532 If the <code>time</code> argument is present, |
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|
3533 this is the time to be formatted |
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|
3534 (see the <a href="#pdf-os.time"><code>os.time</code></a> function for a description of this value). |
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|
3535 Otherwise, <code>date</code> formats the current time. |
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|
3536 |
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|
3537 |
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|
3538 <p> |
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|
3539 If <code>format</code> starts with '<code>!</code>', |
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|
3540 then the date is formatted in Coordinated Universal Time. |
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|
3541 After this optional character, |
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|
3542 if <code>format</code> is the string "<code>*t</code>", |
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|
3543 then <code>date</code> returns a table with the following fields: |
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|
3544 <code>year</code> (four digits), <code>month</code> (1–12), <code>day</code> (1–31), |
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|
3545 <code>hour</code> (0–23), <code>min</code> (0–59), <code>sec</code> (0–61), |
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|
3546 <code>wday</code> (weekday, Sunday is 1), |
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3547 <code>yday</code> (day of the year), |
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|
3548 and <code>isdst</code> (daylight saving flag, a boolean). |
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|
3549 This last field may be absent |
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|
3550 if the information is not available. |
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|
3551 |
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|
3552 |
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|
3553 <p> |
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|
3554 If <code>format</code> is not "<code>*t</code>", |
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|
3555 then <code>date</code> returns the date as a string, |
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|
3556 formatted according to the same rules as the ISO C function <code>strftime</code>. |
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|
3557 |
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|
3558 |
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|
3559 <p> |
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|
3560 When called without arguments, |
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|
3561 <code>date</code> returns a reasonable date and time representation that depends on |
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|
3562 the host system and on the current locale |
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|
3563 (that is, <code>os.date()</code> is equivalent to <code>os.date("%c")</code>). |
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|
3564 |
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changeset
|
3565 |
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|
3566 <p> |
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|
3567 On non-POSIX systems, |
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|
3568 this function may be not thread safe |
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|
3569 because of its reliance on C function <code>gmtime</code> and C function <code>localtime</code>. |
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|
3570 |
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|
3571 |
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diff
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|
3572 |
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|
3573 |
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|
3574 <p> |
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|
3575 <hr><h3><a name="pdf-os.difftime"><code>os.difftime (t2, t1)</code></a></h3> |
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|
3576 |
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diff
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|
3577 |
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|
3578 <p> |
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|
3579 Returns the difference, in seconds, |
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|
3580 from time <code>t1</code> to time <code>t2</code> |
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|
3581 (where the times are values returned by <a href="#pdf-os.time"><code>os.time</code></a>). |
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|
3582 In POSIX, Windows, and some other systems, |
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|
3583 this value is exactly <code>t2</code><em>-</em><code>t1</code>. |
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|
3584 |
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|
3585 |
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|
3586 |
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|
3587 |
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|
3588 <p> |
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|
3589 <hr><h3><a name="pdf-os.execute"><code>os.execute ([command])</code></a></h3> |
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|
3590 |
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diff
changeset
|
3591 |
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|
3592 <p> |
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|
3593 This function is equivalent to the ISO C function <code>system</code>. |
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|
3594 It passes <code>command</code> to be executed by an operating system shell. |
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|
3595 Its first result is <b>true</b> |
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3596 if the command terminated successfully, |
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|
3597 or <b>nil</b> otherwise. |
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|
3598 After this first result |
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3599 the function returns a string plus a number, |
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|
3600 as follows: |
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|
3601 |
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|
3602 <ul> |
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|
3603 |
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|
3604 <li><b>"<code>exit</code>": </b> |
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|
3605 the command terminated normally; |
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|
3606 the following number is the exit status of the command. |
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|
3607 </li> |
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|
3608 |
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|
3609 <li><b>"<code>signal</code>": </b> |
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|
3610 the command was terminated by a signal; |
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|
3611 the following number is the signal that terminated the command. |
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|
3612 </li> |
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|
3613 |
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|
3614 </ul> |
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|
3615 |
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|
3616 <p> |
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|
3617 When called without a <code>command</code>, |
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3618 <code>os.execute</code> returns a boolean that is true if a shell is available. |
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|
3619 |
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|
3620 |
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diff
changeset
|
3621 |
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|
3622 |
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|
3623 <p> |
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|
3624 <hr><h3><a name="pdf-os.exit"><code>os.exit ([code [, close]])</code></a></h3> |
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|
3625 |
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diff
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|
3626 |
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|
3627 <p> |
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|
3628 Calls the ISO C function <code>exit</code> to terminate the host program. |
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|
3629 If <code>code</code> is <b>true</b>, |
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|
3630 the returned status is <code>EXIT_SUCCESS</code>; |
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|
3631 if <code>code</code> is <b>false</b>, |
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|
3632 the returned status is <code>EXIT_FAILURE</code>; |
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|
3633 if <code>code</code> is a number, |
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|
3634 the returned status is this number. |
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3635 The default value for <code>code</code> is <b>true</b>. |
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|
3636 |
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diff
changeset
|
3637 |
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changeset
|
3638 <p> |
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|
3639 If the optional second argument <code>close</code> is true, |
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|
3640 closes the Lua state before exiting. |
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|
3641 |
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|
3642 |
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|
3643 |
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|
3644 |
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|
3645 <p> |
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|
3646 <hr><h3><a name="pdf-os.getenv"><code>os.getenv (varname)</code></a></h3> |
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|
3647 |
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|
3648 |
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|
3649 <p> |
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|
3650 Returns the value of the process environment variable <code>varname</code>, |
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|
3651 or <b>nil</b> if the variable is not defined. |
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|
3652 |
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diff
changeset
|
3653 |
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diff
changeset
|
3654 |
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diff
changeset
|
3655 |
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changeset
|
3656 <p> |
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|
3657 <hr><h3><a name="pdf-os.remove"><code>os.remove (filename)</code></a></h3> |
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|
3658 |
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|
3659 |
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changeset
|
3660 <p> |
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|
3661 Deletes the file (or empty directory, on POSIX systems) |
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|
3662 with the given name. |
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|
3663 If this function fails, it returns <b>nil</b>, |
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|
3664 plus a string describing the error and the error code. |
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|
3665 |
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diff
changeset
|
3666 |
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changeset
|
3667 |
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changeset
|
3668 |
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changeset
|
3669 <p> |
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|
3670 <hr><h3><a name="pdf-os.rename"><code>os.rename (oldname, newname)</code></a></h3> |
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|
3671 |
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changeset
|
3672 |
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changeset
|
3673 <p> |
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|
3674 Renames file or directory named <code>oldname</code> to <code>newname</code>. |
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3675 If this function fails, it returns <b>nil</b>, |
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changeset
|
3676 plus a string describing the error and the error code. |
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changeset
|
3677 |
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changeset
|
3678 |
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changeset
|
3679 |
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changeset
|
3680 |
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|
3681 <p> |
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|
3682 <hr><h3><a name="pdf-os.setlocale"><code>os.setlocale (locale [, category])</code></a></h3> |
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|
3683 |
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diff
changeset
|
3684 |
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changeset
|
3685 <p> |
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|
3686 Sets the current locale of the program. |
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|
3687 <code>locale</code> is a system-dependent string specifying a locale; |
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|
3688 <code>category</code> is an optional string describing which category to change: |
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|
3689 <code>"all"</code>, <code>"collate"</code>, <code>"ctype"</code>, |
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|
3690 <code>"monetary"</code>, <code>"numeric"</code>, or <code>"time"</code>; |
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3691 the default category is <code>"all"</code>. |
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3692 The function returns the name of the new locale, |
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|
3693 or <b>nil</b> if the request cannot be honored. |
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|
3694 |
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|
3695 |
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3696 <p> |
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|
3697 If <code>locale</code> is the empty string, |
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|
3698 the current locale is set to an implementation-defined native locale. |
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|
3699 If <code>locale</code> is the string "<code>C</code>", |
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3700 the current locale is set to the standard C locale. |
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|
3701 |
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|
3702 |
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|
3703 <p> |
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|
3704 When called with <b>nil</b> as the first argument, |
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|
3705 this function only returns the name of the current locale |
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|
3706 for the given category. |
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|
3707 |
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|
3708 |
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|
3709 <p> |
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3710 This function may be not thread safe |
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3711 because of its reliance on C function <code>setlocale</code>. |
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|
3712 |
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|
3713 |
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|
3714 |
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|
3715 |
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|
3716 <p> |
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|
3717 <hr><h3><a name="pdf-os.time"><code>os.time ([table])</code></a></h3> |
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|
3718 |
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|
3719 |
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|
3720 <p> |
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|
3721 Returns the current time when called without arguments, |
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diff
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|
3722 or a time representing the date and time specified by the given table. |
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|
3723 This table must have fields <code>year</code>, <code>month</code>, and <code>day</code>, |
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|
3724 and may have fields |
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|
3725 <code>hour</code> (default is 12), |
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|
3726 <code>min</code> (default is 0), |
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|
3727 <code>sec</code> (default is 0), |
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|
3728 and <code>isdst</code> (default is <b>nil</b>). |
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|
3729 For a description of these fields, see the <a href="#pdf-os.date"><code>os.date</code></a> function. |
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|
3730 |
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|
3731 |
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|
3732 <p> |
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|
3733 The returned value is a number, whose meaning depends on your system. |
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|
3734 In POSIX, Windows, and some other systems, |
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|
3735 this number counts the number |
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|
3736 of seconds since some given start time (the "epoch"). |
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|
3737 In other systems, the meaning is not specified, |
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|
3738 and the number returned by <code>time</code> can be used only as an argument to |
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|
3739 <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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|
3740 |
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|
3741 |
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diff
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|
3742 |
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diff
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|
3743 |
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|
3744 <p> |
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|
3745 <hr><h3><a name="pdf-os.tmpname"><code>os.tmpname ()</code></a></h3> |
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|
3746 |
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diff
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|
3747 |
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|
3748 <p> |
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|
3749 Returns a string with a file name that can |
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|
3750 be used for a temporary file. |
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|
3751 The file must be explicitly opened before its use |
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|
3752 and explicitly removed when no longer needed. |
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|
3753 |
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|
3754 |
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|
3755 <p> |
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diff
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|
3756 On POSIX systems, |
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diff
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|
3757 this function also creates a file with that name, |
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|
3758 to avoid security risks. |
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diff
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|
3759 (Someone else might create the file with wrong permissions |
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|
3760 in the time between getting the name and creating the file.) |
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|
3761 You still have to open the file to use it |
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|
3762 and to remove it (even if you do not use it). |
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|
3763 |
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diff
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|
3764 |
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|
3765 <p> |
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diff
changeset
|
3766 When possible, |
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|
3767 you may prefer to use <a href="#pdf-io.tmpfile"><code>io.tmpfile</code></a>, |
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|
3768 which automatically removes the file when the program ends. |
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|
3769 |
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diff
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|
3770 |
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diff
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|
3771 |
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diff
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|
3772 |
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diff
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|
3773 |
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diff
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|
3774 |
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|
3775 |
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|
3776 <h2>6.10 – <a name="6.10">The Debug Library</a></h2> |
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|
3777 |
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|
3778 <p> |
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|
3779 This library provides |
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|
3780 the functionality of the debug interface (<a href="#4.9">§4.9</a>) to Lua programs. |
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|
3781 You should exert care when using this library. |
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|
3782 Several of its functions |
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|
3783 violate basic assumptions about Lua code |
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|
3784 (e.g., that variables local to a function |
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|
3785 cannot be accessed from outside; |
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|
3786 that userdata metatables cannot be changed by Lua code; |
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|
3787 that Lua programs do not crash) |
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|
3788 and therefore can compromise otherwise secure code. |
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|
3789 Moreover, some functions in this library may be slow. |
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|
3790 |
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|
3791 |
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|
3792 <p> |
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|
3793 All functions in this library are provided |
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|
3794 inside the <a name="pdf-debug"><code>debug</code></a> table. |
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3795 All functions that operate over a thread |
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|
3796 have an optional first argument which is the |
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|
3797 thread to operate over. |
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|
3798 The default is always the current thread. |
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|
3799 |
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|
3800 |
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3801 <p> |
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|
3802 <hr><h3><a name="pdf-debug.debug"><code>debug.debug ()</code></a></h3> |
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|
3803 |
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|
3804 |
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|
3805 <p> |
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|
3806 Enters an interactive mode with the user, |
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3807 running each string that the user enters. |
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3808 Using simple commands and other debug facilities, |
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|
3809 the user can inspect global and local variables, |
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|
3810 change their values, evaluate expressions, and so on. |
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3811 A line containing only the word <code>cont</code> finishes this function, |
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|
3812 so that the caller continues its execution. |
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3813 |
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|
3814 |
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|
3815 <p> |
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3816 Note that commands for <code>debug.debug</code> are not lexically nested |
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3817 within any function and so have no direct access to local variables. |
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|
3818 |
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diff
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|
3819 |
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diff
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|
3820 |
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|
3821 |
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|
3822 <p> |
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|
3823 <hr><h3><a name="pdf-debug.gethook"><code>debug.gethook ([thread])</code></a></h3> |
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|
3824 |
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diff
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|
3825 |
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|
3826 <p> |
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3827 Returns the current hook settings of the thread, as three values: |
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|
3828 the current hook function, the current hook mask, |
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|
3829 and the current hook count |
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|
3830 (as set by the <a href="#pdf-debug.sethook"><code>debug.sethook</code></a> function). |
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|
3831 |
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|
3832 |
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|
3833 |
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|
3834 |
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|
3835 <p> |
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|
3836 <hr><h3><a name="pdf-debug.getinfo"><code>debug.getinfo ([thread,] f [, what])</code></a></h3> |
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|
3837 |
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|
3838 |
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|
3839 <p> |
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|
3840 Returns a table with information about a function. |
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|
3841 You can give the function directly |
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3842 or you can give a number as the value of <code>f</code>, |
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|
3843 which means the function running at level <code>f</code> of the call stack |
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|
3844 of the given thread: |
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|
3845 level 0 is the current function (<code>getinfo</code> itself); |
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|
3846 level 1 is the function that called <code>getinfo</code> |
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3847 (except for tail calls, which do not count on the stack); |
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3848 and so on. |
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|
3849 If <code>f</code> is a number larger than the number of active functions, |
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|
3850 then <code>getinfo</code> returns <b>nil</b>. |
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|
3851 |
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diff
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|
3852 |
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|
3853 <p> |
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|
3854 The returned table can contain all the fields returned by <a href="#lua_getinfo"><code>lua_getinfo</code></a>, |
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|
3855 with the string <code>what</code> describing which fields to fill in. |
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parents:
diff
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|
3856 The default for <code>what</code> is to get all information available, |
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3857 except the table of valid lines. |
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|
3858 If present, |
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diff
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|
3859 the option '<code>f</code>' |
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|
3860 adds a field named <code>func</code> with the function itself. |
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|
3861 If present, |
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|
3862 the option '<code>L</code>' |
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|
3863 adds a field named <code>activelines</code> with the table of |
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|
3864 valid lines. |
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diff
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|
3865 |
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|
3866 |
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|
3867 <p> |
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|
3868 For instance, the expression <code>debug.getinfo(1,"n").name</code> returns |
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|
3869 a table with a name for the current function, |
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|
3870 if a reasonable name can be found, |
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diff
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|
3871 and the expression <code>debug.getinfo(print)</code> |
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|
3872 returns a table with all available information |
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|
3873 about the <a href="#pdf-print"><code>print</code></a> function. |
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|
3874 |
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diff
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|
3875 |
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|
3876 |
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diff
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|
3877 |
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diff
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|
3878 <p> |
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|
3879 <hr><h3><a name="pdf-debug.getlocal"><code>debug.getlocal ([thread,] f, local)</code></a></h3> |
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|
3880 |
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|
3881 |
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|
3882 <p> |
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|
3883 This function returns the name and the value of the local variable |
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|
3884 with index <code>local</code> of the function at level <code>f</code> of the stack. |
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|
3885 This function accesses not only explicit local variables, |
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|
3886 but also parameters, temporaries, etc. |
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|
3887 |
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|
3888 |
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|
3889 <p> |
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|
3890 The first parameter or local variable has index 1, and so on, |
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|
3891 following the order that they are declared in the code, |
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|
3892 counting only the variables that are active |
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|
3893 in the current scope of the function. |
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|
3894 Negative indices refer to vararg parameters; |
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|
3895 -1 is the first vararg parameter. |
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|
3896 The function returns <b>nil</b> if there is no variable with the given index, |
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|
3897 and raises an error when called with a level out of range. |
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|
3898 (You can call <a href="#pdf-debug.getinfo"><code>debug.getinfo</code></a> to check whether the level is valid.) |
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|
3899 |
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|
3900 |
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changeset
|
3901 <p> |
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|
3902 Variable names starting with '<code>(</code>' (open parenthesis) |
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|
3903 represent variables with no known names |
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|
3904 (internal variables such as loop control variables, |
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|
3905 and variables from chunks saved without debug information). |
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|
3906 |
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|
3907 |
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|
3908 <p> |
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|
3909 The parameter <code>f</code> may also be a function. |
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|
3910 In that case, <code>getlocal</code> returns only the name of function parameters. |
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|
3911 |
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|
3912 |
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|
3913 |
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changeset
|
3914 |
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|
3915 <p> |
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|
3916 <hr><h3><a name="pdf-debug.getmetatable"><code>debug.getmetatable (value)</code></a></h3> |
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|
3917 |
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|
3918 |
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|
3919 <p> |
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|
3920 Returns the metatable of the given <code>value</code> |
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|
3921 or <b>nil</b> if it does not have a metatable. |
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|
3922 |
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changeset
|
3923 |
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|
3924 |
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|
3925 |
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|
3926 <p> |
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|
3927 <hr><h3><a name="pdf-debug.getregistry"><code>debug.getregistry ()</code></a></h3> |
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|
3928 |
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changeset
|
3929 |
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|
3930 <p> |
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|
3931 Returns the registry table (see <a href="#4.5">§4.5</a>). |
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|
3932 |
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diff
changeset
|
3933 |
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diff
changeset
|
3934 |
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diff
changeset
|
3935 |
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|
3936 <p> |
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|
3937 <hr><h3><a name="pdf-debug.getupvalue"><code>debug.getupvalue (f, up)</code></a></h3> |
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|
3938 |
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|
3939 |
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|
3940 <p> |
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|
3941 This function returns the name and the value of the upvalue |
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3942 with index <code>up</code> of the function <code>f</code>. |
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3943 The function returns <b>nil</b> if there is no upvalue with the given index. |
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|
3944 |
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|
3945 |
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|
3946 <p> |
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3947 Variable names starting with '<code>(</code>' (open parenthesis) |
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|
3948 represent variables with no known names |
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|
3949 (variables from chunks saved without debug information). |
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|
3950 |
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|
3951 |
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diff
changeset
|
3952 |
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diff
changeset
|
3953 |
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|
3954 <p> |
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|
3955 <hr><h3><a name="pdf-debug.getuservalue"><code>debug.getuservalue (u)</code></a></h3> |
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|
3956 |
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diff
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|
3957 |
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|
3958 <p> |
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3959 Returns the Lua value associated to <code>u</code>. |
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3960 If <code>u</code> is not a userdata, |
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3961 returns <b>nil</b>. |
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|
3962 |
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diff
changeset
|
3963 |
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diff
changeset
|
3964 |
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diff
changeset
|
3965 |
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|
3966 <p> |
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3967 <hr><h3><a name="pdf-debug.sethook"><code>debug.sethook ([thread,] hook, mask [, count])</code></a></h3> |
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|
3968 |
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|
3969 |
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|
3970 <p> |
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3971 Sets the given function as a hook. |
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|
3972 The string <code>mask</code> and the number <code>count</code> describe |
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|
3973 when the hook will be called. |
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|
3974 The string mask may have any combination of the following characters, |
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|
3975 with the given meaning: |
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|
3976 |
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|
3977 <ul> |
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|
3978 <li><b>'<code>c</code>': </b> the hook is called every time Lua calls a function;</li> |
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|
3979 <li><b>'<code>r</code>': </b> the hook is called every time Lua returns from a function;</li> |
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|
3980 <li><b>'<code>l</code>': </b> the hook is called every time Lua enters a new line of code.</li> |
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|
3981 </ul><p> |
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|
3982 Moreover, |
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|
3983 with a <code>count</code> different from zero, |
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|
3984 the hook is called also after every <code>count</code> instructions. |
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|
3985 |
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diff
changeset
|
3986 |
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diff
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|
3987 <p> |
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|
3988 When called without arguments, |
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|
3989 <a href="#pdf-debug.sethook"><code>debug.sethook</code></a> turns off the hook. |
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|
3990 |
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diff
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|
3991 |
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|
3992 <p> |
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|
3993 When the hook is called, its first parameter is a string |
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|
3994 describing the event that has triggered its call: |
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|
3995 <code>"call"</code> (or <code>"tail call"</code>), |
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|
3996 <code>"return"</code>, |
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3997 <code>"line"</code>, and <code>"count"</code>. |
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|
3998 For line events, |
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|
3999 the hook also gets the new line number as its second parameter. |
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|
4000 Inside a hook, |
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|
4001 you can call <code>getinfo</code> with level 2 to get more information about |
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|
4002 the running function |
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|
4003 (level 0 is the <code>getinfo</code> function, |
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|
4004 and level 1 is the hook function). |
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|
4005 |
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|
4006 |
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|
4007 |
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|
4008 |
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|
4009 <p> |
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|
4010 <hr><h3><a name="pdf-debug.setlocal"><code>debug.setlocal ([thread,] level, local, value)</code></a></h3> |
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|
4011 |
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|
4012 |
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|
4013 <p> |
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|
4014 This function assigns the value <code>value</code> to the local variable |
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|
4015 with index <code>local</code> of the function at level <code>level</code> of the stack. |
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|
4016 The function returns <b>nil</b> if there is no local |
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|
4017 variable with the given index, |
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|
4018 and raises an error when called with a <code>level</code> out of range. |
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|
4019 (You can call <code>getinfo</code> to check whether the level is valid.) |
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|
4020 Otherwise, it returns the name of the local variable. |
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|
4021 |
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|
4022 |
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|
4023 <p> |
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|
4024 See <a href="#pdf-debug.getlocal"><code>debug.getlocal</code></a> for more information about |
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|
4025 variable indices and names. |
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|
4026 |
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|
4027 |
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changeset
|
4028 |
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|
4029 |
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|
4030 <p> |
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|
4031 <hr><h3><a name="pdf-debug.setmetatable"><code>debug.setmetatable (value, table)</code></a></h3> |
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|
4032 |
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|
4033 |
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|
4034 <p> |
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|
4035 Sets the metatable for the given <code>value</code> to the given <code>table</code> |
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|
4036 (which can be <b>nil</b>). |
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|
4037 Returns <code>value</code>. |
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|
4038 |
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|
4039 |
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|
4040 |
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|
4041 |
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|
4042 <p> |
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|
4043 <hr><h3><a name="pdf-debug.setupvalue"><code>debug.setupvalue (f, up, value)</code></a></h3> |
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|
4044 |
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changeset
|
4045 |
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|
4046 <p> |
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|
4047 This function assigns the value <code>value</code> to the upvalue |
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|
4048 with index <code>up</code> of the function <code>f</code>. |
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|
4049 The function returns <b>nil</b> if there is no upvalue |
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|
4050 with the given index. |
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|
4051 Otherwise, it returns the name of the upvalue. |
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|
4052 |
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|
4053 |
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changeset
|
4054 |
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changeset
|
4055 |
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|
4056 <p> |
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|
4057 <hr><h3><a name="pdf-debug.setuservalue"><code>debug.setuservalue (udata, value)</code></a></h3> |
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|
4058 |
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changeset
|
4059 |
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|
4060 <p> |
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4061 Sets the given <code>value</code> as |
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4062 the Lua value associated to the given <code>udata</code>. |
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4063 <code>udata</code> must be a full userdata. |
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4064 |
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|
4065 |
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4066 <p> |
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4067 Returns <code>udata</code>. |
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4068 |
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4069 |
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4070 |
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4071 |
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4072 <p> |
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4073 <hr><h3><a name="pdf-debug.traceback"><code>debug.traceback ([thread,] [message [, level]])</code></a></h3> |
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4074 |
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4075 |
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4076 <p> |
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4077 If <code>message</code> is present but is neither a string nor <b>nil</b>, |
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4078 this function returns <code>message</code> without further processing. |
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4079 Otherwise, |
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4080 it returns a string with a traceback of the call stack. |
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4081 The optional <code>message</code> string is appended |
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4082 at the beginning of the traceback. |
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4083 An optional <code>level</code> number tells at which level |
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4084 to start the traceback |
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4085 (default is 1, the function calling <code>traceback</code>). |
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4086 |
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4087 |
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4088 |
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4089 |
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4090 <p> |
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4091 <hr><h3><a name="pdf-debug.upvalueid"><code>debug.upvalueid (f, n)</code></a></h3> |
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4092 |
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4093 |
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4094 <p> |
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4095 Returns a unique identifier (as a light userdata) |
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4096 for the upvalue numbered <code>n</code> |
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4097 from the given function. |
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|
4098 |
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4099 |
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4100 <p> |
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4101 These unique identifiers allow a program to check whether different |
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4102 closures share upvalues. |
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4103 Lua closures that share an upvalue |
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4104 (that is, that access a same external local variable) |
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4105 will return identical ids for those upvalue indices. |
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|
4106 |
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|
4107 |
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|
4108 |
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|
4109 |
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4110 <p> |
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4111 <hr><h3><a name="pdf-debug.upvaluejoin"><code>debug.upvaluejoin (f1, n1, f2, n2)</code></a></h3> |
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4112 |
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|
4113 |
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4114 <p> |
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4115 Make the <code>n1</code>-th upvalue of the Lua closure <code>f1</code> |
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4116 refer to the <code>n2</code>-th upvalue of the Lua closure <code>f2</code>. |
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4117 |
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4118 |
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4119 |
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4120 |
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4121 |
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4122 |
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4123 |
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4124 <h1>7 – <a name="7">Lua Standalone</a></h1> |
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4125 |
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4126 <p> |
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4127 Although Lua has been designed as an extension language, |
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4128 to be embedded in a host C program, |
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4129 it is also frequently used as a standalone language. |
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4130 An interpreter for Lua as a standalone language, |
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4131 called simply <code>lua</code>, |
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4132 is provided with the standard distribution. |
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4133 The standalone interpreter includes |
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4134 all standard libraries, including the debug library. |
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4135 Its usage is: |
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|
4136 |
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4137 <pre> |
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4138 lua [options] [script [args]] |
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4139 </pre><p> |
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|
4140 The options are: |
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|
4141 |
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|
4142 <ul> |
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4143 <li><b><code>-e <em>stat</em></code>: </b> executes string <em>stat</em>;</li> |
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4144 <li><b><code>-l <em>mod</em></code>: </b> "requires" <em>mod</em>;</li> |
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4145 <li><b><code>-i</code>: </b> enters interactive mode after running <em>script</em>;</li> |
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4146 <li><b><code>-v</code>: </b> prints version information;</li> |
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4147 <li><b><code>-E</code>: </b> ignores environment variables;</li> |
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4148 <li><b><code>--</code>: </b> stops handling options;</li> |
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4149 <li><b><code>-</code>: </b> executes <code>stdin</code> as a file and stops handling options.</li> |
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4150 </ul><p> |
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|
4151 After handling its options, <code>lua</code> runs the given <em>script</em>. |
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4152 When called without arguments, |
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4153 <code>lua</code> behaves as <code>lua -v -i</code> |
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4154 when the standard input (<code>stdin</code>) is a terminal, |
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4155 and as <code>lua -</code> otherwise. |
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4156 |
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4157 |
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4158 <p> |
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4159 When called without option <code>-E</code>, |
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4160 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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4161 (or <a name="pdf-LUA_INIT"><code>LUA_INIT</code></a> if the versioned name is not defined) |
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4162 before running any argument. |
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4163 If the variable content has the format <code>@<em>filename</em></code>, |
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4164 then <code>lua</code> executes the file. |
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4165 Otherwise, <code>lua</code> executes the string itself. |
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4166 |
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4167 |
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4168 <p> |
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4169 When called with option <code>-E</code>, |
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4170 besides ignoring <code>LUA_INIT</code>, |
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4171 Lua also ignores |
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4172 the values of <code>LUA_PATH</code> and <code>LUA_CPATH</code>, |
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4173 setting the values of |
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4174 <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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4175 with the default paths defined in <code>luaconf.h</code>. |
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4176 |
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4177 |
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4178 <p> |
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4179 All options are handled in order, except <code>-i</code> and <code>-E</code>. |
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4180 For instance, an invocation like |
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4181 |
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4182 <pre> |
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4183 $ lua -e'a=1' -e 'print(a)' script.lua |
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4184 </pre><p> |
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4185 will first set <code>a</code> to 1, then print the value of <code>a</code>, |
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4186 and finally run the file <code>script.lua</code> with no arguments. |
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4187 (Here <code>$</code> is the shell prompt. Your prompt may be different.) |
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4188 |
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4189 |
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4190 <p> |
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4191 Before running any code, |
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4192 <code>lua</code> collects all command-line arguments |
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4193 in a global table called <code>arg</code>. |
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4194 The script name goes to index 0, |
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4195 the first argument after the script name goes to index 1, |
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4196 and so on. |
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4197 Any arguments before the script name |
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4198 (that is, the interpreter name plus its options) |
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4199 go to negative indices. |
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4200 For instance, in the call |
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4201 |
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4202 <pre> |
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|
4203 $ lua -la b.lua t1 t2 |
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4204 </pre><p> |
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4205 the table is like this: |
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|
4206 |
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4207 <pre> |
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4208 arg = { [-2] = "lua", [-1] = "-la", |
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4209 [0] = "b.lua", |
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4210 [1] = "t1", [2] = "t2" } |
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4211 </pre><p> |
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4212 If there is no script in the call, |
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4213 the interpreter name goes to index 0, |
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4214 followed by the other arguments. |
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4215 For instance, the call |
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|
4216 |
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|
4217 <pre> |
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4218 $ lua -e "print(arg[1])" |
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4219 </pre><p> |
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4220 will print "<code>-e</code>". |
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4221 If there is a script, |
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4222 the script is called with parameters |
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|
4223 <code>arg[1]</code>, ···, <code>arg[#arg]</code>. |
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4224 (Like all chunks in Lua, |
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|
4225 the script is compiled as a vararg function.) |
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|
4226 |
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|
4227 |
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|
4228 <p> |
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4229 In interactive mode, |
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4230 Lua repeatedly prompts and waits for a line. |
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4231 After reading a line, |
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4232 Lua first try to interpret the line as an expression. |
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4233 If it succeeds, it prints its value. |
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4234 Otherwise, it interprets the line as a statement. |
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4235 If you write an incomplete statement, |
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4236 the interpreter waits for its completion |
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4237 by issuing a different prompt. |
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|
4238 |
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|
4239 |
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|
4240 <p> |
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|
4241 In case of unprotected errors in the script, |
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4242 the interpreter reports the error to the standard error stream. |
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4243 If the error object is not a string but |
429
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428
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4244 has a metamethod <code>__to_string</code>, |
371
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4245 the interpreter calls this metamethod to produce the final message. |
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|
4246 Otherwise, the interpreter converts the error object to a string |
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4247 and adds a stack traceback to it. |
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|
4248 |
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|
4249 |
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|
4250 <p> |
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4251 When finishing normally, |
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4252 the interpreter closes its main Lua state |
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|
4253 (see <a href="#lua_close"><code>lua_close</code></a>). |
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4254 The script can avoid this step by |
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|
4255 calling <a href="#pdf-os.exit"><code>os.exit</code></a> to terminate. |
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|
4256 |
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|
4257 |
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|
4258 <p> |
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|
4259 To allow the use of Lua as a |
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|
4260 script interpreter in Unix systems, |
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|
4261 the standalone interpreter skips |
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4262 the first line of a chunk if it starts with <code>#</code>. |
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|
4263 Therefore, Lua scripts can be made into executable programs |
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4264 by using <code>chmod +x</code> and the <code>#!</code> form, |
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|
4265 as in |
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|
4266 |
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|
4267 <pre> |
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|
4268 #!/usr/local/bin/lua |
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|
4269 </pre><p> |
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|
4270 (Of course, |
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|
4271 the location of the Lua interpreter may be different in your machine. |
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|
4272 If <code>lua</code> is in your <code>PATH</code>, |
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|
4273 then |
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|
4274 |
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|
4275 <pre> |
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|
4276 #!/usr/bin/env lua |
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|
4277 </pre><p> |
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|
4278 is a more portable solution.) |
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|
4279 |
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|
4280 |
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|
4281 |
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|
4282 <h1>8 – <a name="8">Incompatibilities with the Previous Version</a></h1> |
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|
4283 |
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|
4284 <p> |
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|
4285 Here we list the incompatibilities that you may find when moving a program |
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4286 from Lua 5.2 to Lua 5.3. |
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4287 You can avoid some incompatibilities by compiling Lua with |
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4288 appropriate options (see file <code>luaconf.h</code>). |
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4289 However, |
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|
4290 all these compatibility options will be removed in the future. |
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|
4291 |
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|
4292 |
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|
4293 <p> |
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|
4294 Lua versions can always change the C API in ways that |
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4295 do not imply source-code changes in a program, |
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4296 such as the numeric values for constants |
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4297 or the implementation of functions as macros. |
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4298 Therefore, |
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|
4299 you should not assume that binaries are compatible between |
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|
4300 different Lua versions. |
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|
4301 Always recompile clients of the Lua API when |
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4302 using a new version. |
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4303 |
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4304 |
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4305 <p> |
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|
4306 Similarly, Lua versions can always change the internal representation |
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4307 of precompiled chunks; |
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|
4308 precompiled chunks are not compatible between different Lua versions. |
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|
4309 |
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|
4310 |
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|
4311 <p> |
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|
4312 The standard paths in the official distribution may |
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|
4313 change between versions. |
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|
4314 |
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|
4315 |
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|
4316 |
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|
4317 <h2>8.1 – <a name="8.1">Changes in the Language</a></h2> |
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|
4318 <ul> |
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|
4319 |
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|
4320 <li> |
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|
4321 The main difference between Lua 5.2 and Lua 5.3 is the |
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|
4322 introduction of an integer subtype for numbers. |
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|
4323 Although this change should not affect "normal" computations, |
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|
4324 some computations |
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|
4325 (mainly those that involve some kind of overflow) |
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|
4326 can give different results. |
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|
4327 |
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|
4328 |
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|
4329 <p> |
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|
4330 You can fix these differences by forcing a number to be a float |
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|
4331 (in Lua 5.2 all numbers were float), |
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4332 in particular writing constants with an ending <code>.0</code> |
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|
4333 or using <code>x = x + 0.0</code> to convert a variable. |
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|
4334 (This recommendation is only for a quick fix |
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|
4335 for an occasional incompatibility; |
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|
4336 it is not a general guideline for good programming. |
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|
4337 For good programming, |
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|
4338 use floats where you need floats |
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|
4339 and integers where you need integers.) |
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|
4340 </li> |
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|
4341 |
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|
4342 <li> |
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|
4343 The conversion of a float to a string now adds a <code>.0</code> suffix |
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|
4344 to the result if it looks like an integer. |
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|
4345 (For instance, the float 2.0 will be printed as <code>2.0</code>, |
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|
4346 not as <code>2</code>.) |
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|
4347 You should always use an explicit format |
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|
4348 when you need a specific format for numbers. |
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|
4349 |
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|
4350 |
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|
4351 <p> |
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|
4352 (Formally this is not an incompatibility, |
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diff
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|
4353 because Lua does not specify how numbers are formatted as strings, |
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parents:
diff
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|
4354 but some programs assumed a specific format.) |
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|
4355 </li> |
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|
4356 |
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|
4357 <li> |
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|
4358 The generational mode for the garbage collector was removed. |
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|
4359 (It was an experimental feature in Lua 5.2.) |
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|
4360 </li> |
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diff
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|
4361 |
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|
4362 </ul> |
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|
4363 |
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|
4364 |
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|
4365 |
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|
4366 |
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|
4367 <h2>8.2 – <a name="8.2">Changes in the Libraries</a></h2> |
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|
4368 <ul> |
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|
4369 |
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|
4370 <li> |
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|
4371 The <code>bit32</code> library has been deprecated. |
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|
4372 It is easy to require a compatible external library or, |
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diff
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|
4373 better yet, to replace its functions with appropriate bitwise operations. |
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|
4374 (Keep in mind that <code>bit32</code> operates on 32-bit integers, |
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|
4375 while the bitwise operators in standard Lua operate on 64-bit integers.) |
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|
4376 </li> |
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diff
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|
4377 |
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|
4378 <li> |
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|
4379 The Table library now respects metamethods |
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diff
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|
4380 for setting and getting elements. |
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parents:
diff
changeset
|
4381 </li> |
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parents:
diff
changeset
|
4382 |
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|
4383 <li> |
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diff
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|
4384 The <a href="#pdf-ipairs"><code>ipairs</code></a> iterator now respects metamethods and |
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diff
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|
4385 its <code>__ipairs</code> metamethod has been deprecated. |
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diff
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|
4386 </li> |
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diff
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|
4387 |
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|
4388 <li> |
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diff
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|
4389 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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parents:
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|
4390 For compatibility, Lua will continue to ignore this character. |
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parents:
diff
changeset
|
4391 </li> |
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parents:
diff
changeset
|
4392 |
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Franklin Schmidt <fschmidt@gmail.com>
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|
4393 <li> |
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|
4394 The following functions were deprecated in the mathematical library: |
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diff
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|
4395 <code>atan2</code>, <code>cosh</code>, <code>sinh</code>, <code>tanh</code>, <code>pow</code>, |
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parents:
diff
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|
4396 <code>frexp</code>, and <code>ldexp</code>. |
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diff
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|
4397 You can replace <code>math.pow(x,y)</code> with <code>x^y</code>; |
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parents:
diff
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|
4398 you can replace <code>math.atan2</code> with <code>math.atan</code>, |
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parents:
diff
changeset
|
4399 which now accepts one or two parameters; |
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parents:
diff
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|
4400 you can replace <code>math.ldexp(x,exp)</code> with <code>x * 2.0^exp</code>. |
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|
4401 For the other operations, |
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parents:
diff
changeset
|
4402 you can either use an external library or |
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parents:
diff
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|
4403 implement them in Lua. |
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parents:
diff
changeset
|
4404 </li> |
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changeset
|
4405 |
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|
4406 <li> |
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|
4407 The searcher for C loaders used by <a href="#pdf-require"><code>require</code></a> |
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|
4408 changed the way it handles versioned names. |
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|
4409 Now, the version should come after the module name |
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|
4410 (as is usual in most other tools). |
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|
4411 For compatibility, that searcher still tries the old format |
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|
4412 if it cannot find an open function according to the new style. |
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|
4413 (Lua 5.2 already worked that way, |
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|
4414 but it did not document the change.) |
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changeset
|
4415 </li> |
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changeset
|
4416 |
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|
4417 </ul> |
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changeset
|
4418 |
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|
4419 |
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changeset
|
4420 |
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changeset
|
4421 |
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|
4422 <h2>8.3 – <a name="8.3">Changes in the API</a></h2> |
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|
4423 |
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|
4424 |
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|
4425 <ul> |
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|
4426 |
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|
4427 <li> |
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|
4428 Continuation functions now receive as parameters what they needed |
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|
4429 to get through <code>lua_getctx</code>, |
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changeset
|
4430 so <code>lua_getctx</code> has been removed. |
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changeset
|
4431 Adapt your code accordingly. |
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changeset
|
4432 </li> |
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4433 |
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4434 <li> |
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4435 Function <a href="#lua_dump"><code>lua_dump</code></a> has an extra parameter, <code>strip</code>. |
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4436 Use 0 as the value of this parameter to get the old behavior. |
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4437 </li> |
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|
4438 |
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|
4439 <li> |
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|
4440 Functions to inject/project unsigned integers |
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4441 (<code>lua_pushunsigned</code>, <code>lua_tounsigned</code>, <code>lua_tounsignedx</code>, |
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4442 <code>luaL_checkunsigned</code>, <code>luaL_optunsigned</code>) |
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4443 were deprecated. |
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4444 Use their signed equivalents with a type cast. |
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|
4445 </li> |
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|
4446 |
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|
4447 <li> |
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|
4448 Macros to project non-default integer types |
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4449 (<code>luaL_checkint</code>, <code>luaL_optint</code>, <code>luaL_checklong</code>, <code>luaL_optlong</code>) |
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4450 were deprecated. |
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4451 Use their equivalent over <a href="#lua_Integer"><code>lua_Integer</code></a> with a type cast |
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|
4452 (or, when possible, use <a href="#lua_Integer"><code>lua_Integer</code></a> in your code). |
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|
4453 </li> |
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|
4454 |
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4455 </ul> |
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|
4456 |
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4457 |
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4458 |
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|
4459 |
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|
4460 <h1>9 – <a name="9">The Complete Syntax of Lua</a></h1> |
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4461 |
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|
4462 <p> |
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4463 Here is the complete syntax of Lua in extended BNF. |
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4464 As usual in extended BNF, |
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4465 {A} means 0 or more As, |
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|
4466 and [A] means an optional A. |
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4467 (For operator precedences, see <a href="#3.4.8">§3.4.8</a>; |
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4468 for a description of the terminals |
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|
4469 Name, Numeral, |
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|
4470 and LiteralString, see <a href="#3.1">§3.1</a>.) |
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|
4471 |
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|
4472 |
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|
4473 |
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|
4474 |
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|
4475 <pre> |
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|
4476 |
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|
4477 chunk ::= block |
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|
4478 |
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|
4479 block ::= {stat} [retstat] |
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|
4480 |
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|
4481 stat ::= ‘<b>;</b>’ | |
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|
4482 varlist ‘<b>=</b>’ explist | |
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4483 functioncall | |
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|
4484 label | |
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|
4485 <b>break</b> | |
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|
4486 <b>goto</b> Name | |
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4487 <b>do</b> block <b>end</b> | |
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|
4488 <b>while</b> exp <b>do</b> block <b>end</b> | |
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4489 <b>repeat</b> block <b>until</b> exp | |
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4490 <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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|
4491 <b>for</b> Name ‘<b>=</b>’ exp ‘<b>,</b>’ exp [‘<b>,</b>’ exp] <b>do</b> block <b>end</b> | |
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|
4492 <b>for</b> namelist <b>in</b> explist <b>do</b> block <b>end</b> | |
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4493 <b>function</b> funcname funcbody | |
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4494 <b>local</b> <b>function</b> Name funcbody | |
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4495 <b>local</b> namelist [‘<b>=</b>’ explist] |
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|
4496 |
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|
4497 retstat ::= <b>return</b> [explist] [‘<b>;</b>’] |
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4498 |
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|
4499 label ::= ‘<b>::</b>’ Name ‘<b>::</b>’ |
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|
4500 |
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4501 funcname ::= Name {‘<b>.</b>’ Name} [‘<b>:</b>’ Name] |
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|
4502 |
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|
4503 varlist ::= var {‘<b>,</b>’ var} |
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|
4504 |
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|
4505 var ::= Name | prefixexp ‘<b>[</b>’ exp ‘<b>]</b>’ | prefixexp ‘<b>.</b>’ Name |
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|
4506 |
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4507 namelist ::= Name {‘<b>,</b>’ Name} |
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|
4508 |
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4509 explist ::= exp {‘<b>,</b>’ exp} |
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|
4510 |
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|
4511 exp ::= <b>nil</b> | <b>false</b> | <b>true</b> | Numeral | LiteralString | ‘<b>...</b>’ | functiondef | |
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4512 prefixexp | tableconstructor | exp binop exp | unop exp |
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4513 |
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|
4514 prefixexp ::= var | functioncall | ‘<b>(</b>’ exp ‘<b>)</b>’ |
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|
4515 |
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4516 functioncall ::= prefixexp args | prefixexp ‘<b>:</b>’ Name args |
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4517 |
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4518 args ::= ‘<b>(</b>’ [explist] ‘<b>)</b>’ | tableconstructor | LiteralString |
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4519 |
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4520 functiondef ::= <b>function</b> funcbody |
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4521 |
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4522 funcbody ::= ‘<b>(</b>’ [parlist] ‘<b>)</b>’ block <b>end</b> |
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4523 |
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4524 parlist ::= namelist [‘<b>,</b>’ ‘<b>...</b>’] | ‘<b>...</b>’ |
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4525 |
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4526 tableconstructor ::= ‘<b>{</b>’ [fieldlist] ‘<b>}</b>’ |
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4527 |
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4528 fieldlist ::= field {fieldsep field} [fieldsep] |
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4529 |
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4530 field ::= ‘<b>[</b>’ exp ‘<b>]</b>’ ‘<b>=</b>’ exp | Name ‘<b>=</b>’ exp | exp |
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4531 |
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4532 fieldsep ::= ‘<b>,</b>’ | ‘<b>;</b>’ |
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4533 |
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|
4534 binop ::= ‘<b>+</b>’ | ‘<b>-</b>’ | ‘<b>*</b>’ | ‘<b>/</b>’ | ‘<b>//</b>’ | ‘<b>^</b>’ | ‘<b>%</b>’ | |
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4535 ‘<b>&</b>’ | ‘<b>~</b>’ | ‘<b>|</b>’ | ‘<b>>></b>’ | ‘<b><<</b>’ | ‘<b>..</b>’ | |
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4536 ‘<b><</b>’ | ‘<b><=</b>’ | ‘<b>></b>’ | ‘<b>>=</b>’ | ‘<b>==</b>’ | ‘<b>~=</b>’ | |
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4537 <b>and</b> | <b>or</b> |
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4538 |
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4539 unop ::= ‘<b>-</b>’ | <b>not</b> | ‘<b>#</b>’ | ‘<b>~</b>’ |
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4540 |
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|
4541 </pre> |
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|
4542 |
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4543 <p> |
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4544 |
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4545 |
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4546 |
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4547 |
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4548 |
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4550 |
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4551 |
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4552 <HR> |
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4553 <SMALL CLASS="footer"> |
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4554 Last update: |
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4555 Fri Jan 16 00:58:20 BRST 2015 |
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4556 </SMALL> |
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4557 <!-- |
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4558 Last change: minor edit |
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4559 --> |
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4560 |
372 | 4561 </div> |
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4562 |
391
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4563 </body> |
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4564 </html> |
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4565 <% |
386
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