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MUC: Don't unconditionally broadcast presence with role="none" Detailed explanation in de607875d4bd. A presence with role="none" (which is always type="unavailable") should only be broadcast if available presence was previously broadcast for that occupant.
author Matthew Wild <mwild1@gmail.com>
date Thu, 12 Mar 2020 14:13:22 +0000
parent 9939:3a7f822f6edd
child 11000:d9aae4734f38
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1
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2 # Prosody Coding Style Guide
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3
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4 This style guides lists the coding conventions used in the
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5 [Prosody](https://prosody.im/) project. It is based heavily on the [style guide used by the LuaRocks project](https://github.com/luarocks/lua-style-guide).
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6
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7 ## Indentation and formatting
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8
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9 * Prosody code is indented with tabs at the start of the line, a single
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10 tab per logical indent level:
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11
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12 ```lua
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13 for i, pkg in ipairs(packages) do
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14 for name, version in pairs(pkg) do
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15 if name == searched then
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16 print(version);
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17 end
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18 end
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19 end
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20 ```
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21
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22 Tab width is configurable in editors, so never assume a particular width.
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23 Specically this means you should not mix tabs and spaces, or use tabs for
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24 alignment of items at different indentation levels.
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25
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26 * Use LF (Unix) line endings.
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27
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28 ## Comments
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29
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30 * Comments are encouraged where necessary to explain non-obvious code.
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31
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32 * In general comments should be used to explain 'why', not 'how'
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33
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34 ### Comment tags
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35
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36 A comment may be prefixed with one of the following tags:
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37
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38 * **FIXME**: Indicates a serious problem with the code that should be addressed
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39 * **TODO**: Indicates an open task, feature request or code restructuring that
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40 is primarily of interest to developers (otherwise it should be in the
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41 issue tracker).
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42 * **COMPAT**: Must be used on all code that is present only for backwards-compatibility,
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43 and may be removed one day. For example code that is added to support old
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44 or buggy third-party software or dependencies.
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45
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46 **Example:**
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47
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48 ```lua
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49 -- TODO: implement method
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50 local function something()
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51 -- FIXME: check conditions
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52 end
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53
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54 ```
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55
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56 ## Variable names
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57
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58 * Variable names with larger scope should be more descriptive than those with
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59 smaller scope. One-letter variable names should be avoided except for very
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60 small scopes (less than ten lines) or for iterators.
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61
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62 * `i` should be used only as a counter variable in for loops (either numeric for
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63 or `ipairs`).
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64
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65 * Prefer more descriptive names than `k` and `v` when iterating with `pairs`,
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66 unless you are writing a function that operates on generic tables.
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67
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68 * Use `_` for ignored variables (e.g. in for loops:)
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69
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70 ```lua
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71 for _, item in ipairs(items) do
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72 do_something_with_item(item);
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73 end
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74 ```
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75
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76 * Generally all identifiers (variables and function names) should use `snake_case`,
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77 i.e. lowercase words joined by `_`.
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78
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79 ```lua
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80 -- bad
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81 local OBJEcttsssss = {}
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82 local thisIsMyObject = {}
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83 local c = function()
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84 -- ...stuff...
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85 end
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86
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87 -- good
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88 local this_is_my_object = {};
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89
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90 local function do_that_thing()
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91 -- ...stuff...
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92 end
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93 ```
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94
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95 > **Rationale:** The standard library uses lowercase APIs, with `joinedlowercase`
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96 names, but this does not scale too well for more complex APIs. `snake_case`
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97 tends to look good enough and not too out-of-place along side the standard
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98 APIs.
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99
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100 ```lua
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101 for _, name in pairs(names) do
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102 -- ...stuff...
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103 end
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104 ```
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105
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106 * Prefer using `is_` when naming boolean functions:
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107
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108 ```lua
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109 -- bad
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110 local function evil(alignment)
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111 return alignment < 100
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112 end
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113
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114 -- good
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115 local function is_evil(alignment)
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116 return alignment < 100;
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117 end
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118 ```
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119
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120 * `UPPER_CASE` is to be used sparingly, with "constants" only.
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121
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122 > **Rationale:** "Sparingly", since Lua does not have real constants. This
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123 notation is most useful in libraries that bind C libraries, when bringing over
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124 constants from C.
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125
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126 * Do not use uppercase names starting with `_`, they are reserved by Lua.
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127
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128 ## Tables
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129
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130 * When creating a table, prefer populating its fields all at once, if possible:
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131
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132 ```lua
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133 local player = { name = "Jack", class = "Rogue" };
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134 ```
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135
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136 * Items should be separated by commas. If there are many items, put each
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137 key/value on a separate line and use a semi-colon after each item (including
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138 the last one):
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139
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140 ```lua
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141 local player = {
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142 name = "Jack";
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143 class = "Rogue";
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144 }
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145 ```
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146
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147 > **Rationale:** This makes the structure of your tables more evident at a glance.
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148 Trailing semi-colons make it quicker to add new fields and produces shorter diffs.
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149
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150 * Use plain `key` syntax whenever possible, use `["key"]` syntax when using names
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151 that can't be represented as identifiers and avoid mixing representations in
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152 a declaration:
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153
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154 ```lua
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155 local mytable = {
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156 ["1394-E"] = val1;
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157 ["UTF-8"] = val2;
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158 ["and"] = val2;
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159 }
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160 ```
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161
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162 ## Strings
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163
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164 * Use `"double quotes"` for strings; use `'single quotes'` when writing strings
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165 that contain double quotes.
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166
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167 ```lua
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168 local name = "Prosody";
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169 local sentence = 'The name of the program is "Prosody"';
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170 ```
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171
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172 > **Rationale:** Double quotes are used as string delimiters in a larger number of
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173 programming languages. Single quotes are useful for avoiding escaping when
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174 using double quotes in literals.
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175
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176 ## Line lengths
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177
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178 * There are no hard or soft limits on line lengths. Line lengths are naturally
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179 limited by using one statement per line. If that still produces lines that are
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180 too long (e.g. an expression that produces a line over 256-characters long,
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181 for example), this means the expression is too complex and would do better
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182 split into subexpressions with reasonable names.
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183
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184 > **Rationale:** No one works on VT100 terminals anymore. If line lengths are a proxy
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185 for code complexity, we should address code complexity instead of using line
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186 breaks to fit mind-bending statements over multiple lines.
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187
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188 ## Function declaration syntax
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189
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190 * Prefer function syntax over variable syntax. This helps differentiate between
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191 named and anonymous functions.
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192
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193 ```lua
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194 -- bad
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195 local nope = function(name, options)
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196 -- ...stuff...
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197 end
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198
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199 -- good
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200 local function yup(name, options)
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201 -- ...stuff...
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202 end
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203 ```
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204
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205 * Perform validation early and return as early as possible.
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206
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207 ```lua
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208 -- bad
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209 local function is_good_name(name, options, arg)
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210 local is_good = #name > 3
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211 is_good = is_good and #name < 30
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212
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213 -- ...stuff...
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214
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215 return is_good
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216 end
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217
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218 -- good
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219 local function is_good_name(name, options, args)
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220 if #name < 3 or #name > 30 then
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221 return false;
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222 end
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223
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224 -- ...stuff...
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225
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226 return true;
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227 end
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228 ```
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229
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230 ## Function calls
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231
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232 * Even though Lua allows it, generally you should not omit parentheses
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233 for functions that take a unique string literal argument.
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234
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235 ```lua
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236 -- bad
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237 local data = get_data"KRP"..tostring(area_number)
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238 -- good
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239 local data = get_data("KRP"..tostring(area_number));
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240 local data = get_data("KRP")..tostring(area_number);
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241 ```
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242
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243 > **Rationale:** It is not obvious at a glace what the precedence rules are
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244 when omitting the parentheses in a function call. Can you quickly tell which
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245 of the two "good" examples in equivalent to the "bad" one? (It's the second
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246 one).
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247
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248 * You should not omit parenthesis for functions that take a unique table
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249 argument on a single line. You may do so for table arguments that span several
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250 lines.
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251
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252 ```lua
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253 local an_instance = a_module.new {
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254 a_parameter = 42;
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255 another_parameter = "yay";
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256 }
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257 ```
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258
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259 > **Rationale:** The use as in `a_module.new` above occurs alone in a statement,
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260 so there are no precedence issues.
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261
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262 ## Table attributes
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263
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264 * Use dot notation when accessing known properties.
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265
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266 ```lua
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267 local luke = {
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268 jedi = true;
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269 age = 28;
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270 }
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271
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272 -- bad
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273 local is_jedi = luke["jedi"]
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274
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275 -- good
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276 local is_jedi = luke.jedi;
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277 ```
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278
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279 * Use subscript notation `[]` when accessing properties with a variable or if using a table as a list.
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280
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281 ```lua
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282 local vehicles = load_vehicles_from_disk("vehicles.dat")
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283
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284 if vehicles["Porsche"] then
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285 porsche_handler(vehicles["Porsche"]);
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286 vehicles["Porsche"] = nil;
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287 end
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288 for name, cars in pairs(vehicles) do
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289 regular_handler(cars);
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290 end
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291 ```
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292
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293 > **Rationale:** Using dot notation makes it clearer that the given key is meant
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294 to be used as a record/object field.
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295
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296 ## Functions in tables
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297
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298 * When declaring modules and classes, declare functions external to the table definition:
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299
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300 ```lua
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301 local my_module = {};
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302
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303 function my_module.a_function(x)
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304 -- code
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305 end
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306 ```
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307
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308 * When declaring metatables, declare function internal to the table definition.
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309
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310 ```lua
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311 local version_mt = {
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312 __eq = function(a, b)
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313 -- code
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314 end;
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315 __lt = function(a, b)
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316 -- code
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317 end;
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318 }
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319 ```
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320
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321 > **Rationale:** Metatables contain special behavior that affect the tables
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322 they're assigned (and are used implicitly at the call site), so it's good to
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323 be able to get a view of the complete behavior of the metatable at a glance.
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324
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325 This is not as important for objects and modules, which usually have way more
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326 code, and which don't fit in a single screen anyway, so nesting them inside
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327 the table does not gain much: when scrolling a longer file, it is more evident
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328 that `check_version` is a method of `Api` if it says `function Api:check_version()`
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329 than if it says `check_version = function()` under some indentation level.
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330
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331 ## Variable declaration
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332
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333 * Always use `local` to declare variables.
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334
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335 ```lua
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336 -- bad
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337 superpower = get_superpower()
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338
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339 -- good
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340 local superpower = get_superpower();
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341 ```
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342
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343 > **Rationale:** Not doing so will result in global variables to avoid polluting
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344 the global namespace.
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345
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346 ## Variable scope
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347
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348 * Assign variables with the smallest possible scope.
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349
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350 ```lua
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351 -- bad
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352 local function good()
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353 local name = get_name()
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354
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355 test()
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356 print("doing stuff..")
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357
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358 --...other stuff...
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359
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360 if name == "test" then
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361 return false
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362 end
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363
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364 return name
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365 end
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366
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367 -- good
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368 local bad = function()
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369 test();
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370 print("doing stuff..");
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371
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372 --...other stuff...
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373
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374 local name = get_name();
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375
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376 if name == "test" then
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377 return false;
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378 end
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379
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380 return name;
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381 end
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382 ```
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383
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384 > **Rationale:** Lua has proper lexical scoping. Declaring the function later means that its
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385 scope is smaller, so this makes it easier to check for the effects of a variable.
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386
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387 ## Conditional expressions
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388
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389 * False and nil are falsy in conditional expressions. Use shortcuts when you
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390 can, unless you need to know the difference between false and nil.
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391
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392 ```lua
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393 -- bad
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394 if name ~= nil then
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395 -- ...stuff...
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396 end
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397
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398 -- good
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399 if name then
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400 -- ...stuff...
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401 end
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402 ```
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403
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404 * Avoid designing APIs which depend on the difference between `nil` and `false`.
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405
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406 * Use the `and`/`or` idiom for the pseudo-ternary operator when it results in
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407 more straightforward code. When nesting expressions, use parentheses to make it
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408 easier to scan visually:
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409
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410 ```lua
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411 local function default_name(name)
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412 -- return the default "Waldo" if name is nil
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413 return name or "Waldo";
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414 end
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415
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416 local function brew_coffee(machine)
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417 return (machine and machine.is_loaded) and "coffee brewing" or "fill your water";
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418 end
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419 ```
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420
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421 Note that the `x and y or z` as a substitute for `x ? y : z` does not work if
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422 `y` may be `nil` or `false` so avoid it altogether for returning booleans or
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423 values which may be nil.
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424
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425 ## Blocks
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426
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427 * Use single-line blocks only for `then return`, `then break` and `function return` (a.k.a "lambda") constructs:
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428
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Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
429 ```lua
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
430 -- good
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
431 if test then break end
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
432
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
433 -- good
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
434 if not ok then return nil, "this failed for this reason: " .. reason end
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
435
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
436 -- good
9939
3a7f822f6edd doc/coding_style: apply consistent semi-colon usage
marc0s <marcos@tenak.net>
parents: 9900
diff changeset
437 use_callback(x, function(k) return k.last end);
9858
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
438
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
439 -- good
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
440 if test then
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
441 return false
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
442 end
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
443
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
444 -- bad
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
445 if test < 1 and do_complicated_function(test) == false or seven == 8 and nine == 10 then do_other_complicated_function() end
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
446
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
447 -- good
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
448 if test < 1 and do_complicated_function(test) == false or seven == 8 and nine == 10 then
9939
3a7f822f6edd doc/coding_style: apply consistent semi-colon usage
marc0s <marcos@tenak.net>
parents: 9900
diff changeset
449 do_other_complicated_function();
3a7f822f6edd doc/coding_style: apply consistent semi-colon usage
marc0s <marcos@tenak.net>
parents: 9900
diff changeset
450 return false;
9858
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
451 end
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
452 ```
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
453
9900
f2104b36f673 doc/coding_style: The codebase uses semicolons
Kim Alvefur <zash@zash.se>
parents: 9899
diff changeset
454 * Separate statements onto multiple lines. Use semicolons as statement terminators.
9858
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
455
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
456 ```lua
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
457 -- bad
9900
f2104b36f673 doc/coding_style: The codebase uses semicolons
Kim Alvefur <zash@zash.se>
parents: 9899
diff changeset
458 local whatever = "sure"
f2104b36f673 doc/coding_style: The codebase uses semicolons
Kim Alvefur <zash@zash.se>
parents: 9899
diff changeset
459 a = 1 b = 2
9858
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
460
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
461 -- good
9900
f2104b36f673 doc/coding_style: The codebase uses semicolons
Kim Alvefur <zash@zash.se>
parents: 9899
diff changeset
462 local whatever = "sure";
f2104b36f673 doc/coding_style: The codebase uses semicolons
Kim Alvefur <zash@zash.se>
parents: 9899
diff changeset
463 a = 1;
f2104b36f673 doc/coding_style: The codebase uses semicolons
Kim Alvefur <zash@zash.se>
parents: 9899
diff changeset
464 b = 2;
9858
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
465 ```
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
466
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
467 ## Spacing
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
468
9899
8c831c76fc94 doc/coding_style: Trim trailing whitespace
Kim Alvefur <zash@zash.se>
parents: 9898
diff changeset
469 * Use a space after `--`.
9858
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
470
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
471 ```lua
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
472 --bad
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
473 -- good
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
474 ```
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
475
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
476 * Always put a space after commas and between operators and assignment signs:
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
477
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
478 ```lua
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
479 -- bad
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
480 local x = y*9
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
481 local numbers={1,2,3}
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
482 numbers={1 , 2 , 3}
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
483 numbers={1 ,2 ,3}
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
484 local strings = { "hello"
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
485 , "Lua"
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
486 , "world"
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
487 }
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
488 dog.set( "attr",{
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
489 age="1 year",
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
490 breed="Bernese Mountain Dog"
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
491 })
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
492
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
493 -- good
9939
3a7f822f6edd doc/coding_style: apply consistent semi-colon usage
marc0s <marcos@tenak.net>
parents: 9900
diff changeset
494 local x = y * 9;
3a7f822f6edd doc/coding_style: apply consistent semi-colon usage
marc0s <marcos@tenak.net>
parents: 9900
diff changeset
495 local numbers = {1, 2, 3};
9858
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
496 local strings = {
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
497 "hello";
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
498 "Lua";
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
499 "world";
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
500 }
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
501 dog.set("attr", {
9939
3a7f822f6edd doc/coding_style: apply consistent semi-colon usage
marc0s <marcos@tenak.net>
parents: 9900
diff changeset
502 age = "1 year";
3a7f822f6edd doc/coding_style: apply consistent semi-colon usage
marc0s <marcos@tenak.net>
parents: 9900
diff changeset
503 breed = "Bernese Mountain Dog";
3a7f822f6edd doc/coding_style: apply consistent semi-colon usage
marc0s <marcos@tenak.net>
parents: 9900
diff changeset
504 });
9858
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
505 ```
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
506
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
507 * Indent tables and functions according to the start of the line, not the construct:
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
508
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
509 ```lua
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
510 -- bad
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
511 local my_table = {
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
512 "hello",
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
513 "world",
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
514 }
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
515 using_a_callback(x, function(...)
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
516 print("hello")
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
517 end)
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
518
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
519 -- good
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
520 local my_table = {
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
521 "hello";
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
522 "world";
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
523 }
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
524 using_a_callback(x, function(...)
9939
3a7f822f6edd doc/coding_style: apply consistent semi-colon usage
marc0s <marcos@tenak.net>
parents: 9900
diff changeset
525 print("hello");
9858
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
526 end)
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
527 ```
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
528
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
529 > **Rationale:** This keep indentation levels aligned at predictable places. You don't
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
530 need to realign the entire block if something in the first line changes (such as
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
531 replacing `x` with `xy` in the `using_a_callback` example above).
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
532
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
533 * The concatenation operator gets a pass for avoiding spaces:
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
534
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
535 ```lua
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
536 -- okay
9939
3a7f822f6edd doc/coding_style: apply consistent semi-colon usage
marc0s <marcos@tenak.net>
parents: 9900
diff changeset
537 local message = "Hello, "..user.."! This is your day # "..day.." in our platform!";
9858
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
538 ```
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
539
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
540 > **Rationale:** Being at the baseline, the dots already provide some visual spacing.
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
541
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
542 * No spaces after the name of a function in a declaration or in its arguments:
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
543
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
544 ```lua
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
545 -- bad
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
546 local function hello ( name, language )
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
547 -- code
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
548 end
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
549
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
550 -- good
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
551 local function hello(name, language)
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
552 -- code
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
553 end
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
554 ```
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
555
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
556 * Add blank lines between functions:
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
557
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
558 ```lua
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
559 -- bad
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
560 local function foo()
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
561 -- code
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
562 end
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
563 local function bar()
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
564 -- code
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
565 end
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
566
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
567 -- good
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
568 local function foo()
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
569 -- code
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
570 end
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
571
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
572 local function bar()
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
573 -- code
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
574 end
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
575 ```
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
576
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parents:
diff changeset
577 * Avoid aligning variable declarations:
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
578
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
579 ```lua
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
580 -- bad
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
581 local a = 1
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
582 local long_identifier = 2
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
583
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
584 -- good
9939
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marc0s <marcos@tenak.net>
parents: 9900
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585 local a = 1;
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marc0s <marcos@tenak.net>
parents: 9900
diff changeset
586 local long_identifier = 2;
9858
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Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
587 ```
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
588
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
589 > **Rationale:** This produces extra diffs which add noise to `git blame`.
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
590
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
591 * Alignment is occasionally useful when logical correspondence is to be highlighted:
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
592
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
593 ```lua
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
594 -- okay
9939
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parents: 9900
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595 sys_command(form, UI_FORM_UPDATE_NODE, "a", FORM_NODE_HIDDEN, false);
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parents: 9900
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596 sys_command(form, UI_FORM_UPDATE_NODE, "sample", FORM_NODE_VISIBLE, false);
9858
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diff changeset
597 ```
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
598
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Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
599 ## Typing
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
600
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
601 * In non-performance critical code, it can be useful to add type-checking assertions
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
602 for function arguments:
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
603
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
604 ```lua
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
605 function manif.load_manifest(repo_url, lua_version)
9939
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606 assert(type(repo_url) == "string");
3a7f822f6edd doc/coding_style: apply consistent semi-colon usage
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607 assert(type(lua_version) == "string" or not lua_version);
9858
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608
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
609 -- ...
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
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610 end
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
611 ```
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
612
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
613 * Use the standard functions for type conversion, avoid relying on coercion:
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
614
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
615 ```lua
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
616 -- bad
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Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
617 local total_score = review_score .. ""
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Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
618
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
619 -- good
9939
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620 local total_score = tostring(review_score);
9858
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diff changeset
621 ```
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
622
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
623 ## Errors
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
624
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
625 * Functions that can fail for reasons that are expected (e.g. I/O) should
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
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parents:
diff changeset
626 return `nil` and a (string) error message on error, possibly followed by other
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
627 return values such as an error code.
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
628
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
629 * On errors such as API misuse, an error should be thrown, either with `error()`
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
630 or `assert()`.
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
631
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
632 ## Modules
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
633
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Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
634 Follow [these guidelines](http://hisham.hm/2014/01/02/how-to-write-lua-modules-in-a-post-module-world/) for writing modules. In short:
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Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
635
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
636 * Always require a module into a local variable named after the last component of the module’s full name.
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
637
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Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
638 ```lua
9939
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639 local bar = require("foo.bar"); -- requiring the module
9858
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diff changeset
640
9939
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diff changeset
641 bar.say("hello"); -- using the module
9858
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parents:
diff changeset
642 ```
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
643
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
644 * Don’t rename modules arbitrarily:
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
645
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
646 ```lua
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
647 -- bad
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
648 local skt = require("socket")
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
649 ```
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
650
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
651 > **Rationale:** Code is much harder to read if we have to keep going back to the top
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
652 to check how you chose to call a module.
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
653
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
654 * Start a module by declaring its table using the same all-lowercase local
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parents:
diff changeset
655 name that will be used to require it. You may use an LDoc comment to identify
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
656 the whole module path.
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
657
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
658 ```lua
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
659 --- @module foo.bar
9939
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660 local bar = {};
9858
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diff changeset
661 ```
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
662
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Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
663 * Try to use names that won't clash with your local variables. For instance, don't
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
664 name your module something like “size”.
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
665
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Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
666 * Use `local function` to declare _local_ functions only: that is, functions
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
667 that won’t be accessible from outside the module.
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
668
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Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
669 That is, `local function helper_foo()` means that `helper_foo` is really local.
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
670
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Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
671 * Public functions are declared in the module table, with dot syntax:
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
672
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Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
673 ```lua
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
674 function bar.say(greeting)
9939
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parents: 9900
diff changeset
675 print(greeting);
9858
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diff changeset
676 end
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
677 ```
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
678
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
679 > **Rationale:** Visibility rules are made explicit through syntax.
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
680
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
681 * Do not set any globals in your module and always return a table in the end.
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
682
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
683 * If you would like your module to be used as a function, you may set the
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
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parents:
diff changeset
684 `__call` metamethod on the module table instead.
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
685
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
686 > **Rationale:** Modules should return tables in order to be amenable to have their
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
687 contents inspected via the Lua interactive interpreter or other tools.
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
688
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
689 * Requiring a module should cause no side-effect other than loading other
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
690 modules and returning the module table.
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
691
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
692 * A module should not have state. If a module needs configuration, turn
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
693 it into a factory. For example, do not make something like this:
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
694
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
695 ```lua
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
696 -- bad
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
697 local mp = require "MessagePack"
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
698 mp.set_integer("unsigned")
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
699 ```
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
700
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
701 and do something like this instead:
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
702
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
703 ```lua
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
704 -- good
9939
3a7f822f6edd doc/coding_style: apply consistent semi-colon usage
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diff changeset
705 local messagepack = require("messagepack");
3a7f822f6edd doc/coding_style: apply consistent semi-colon usage
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parents: 9900
diff changeset
706 local mpack = messagepack.new({integer = "unsigned"});
9858
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parents:
diff changeset
707 ```
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
708
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
709 * The invocation of require may omit parentheses around the module name:
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
710
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
711 ```lua
9939
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diff changeset
712 local bla = require "bla";
9858
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parents:
diff changeset
713 ```
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
714
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
715 ## Metatables, classes and objects
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
716
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Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
717 If creating a new type of object that has a metatable and methods, the
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Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
718 metatable and methods table should be separate, and the metatable name
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
719 should end with `_mt`.
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
720
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
721 ```lua
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
722 local mytype_methods = {};
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
723 local mytype_mt = { __index = mytype_methods };
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
724
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
725 function mytype_methods:add_new_thing(thing)
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
726 end
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
727
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
728 local function new()
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
729 return setmetatable({}, mytype_mt);
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
730 end
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
731
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
732 return { new = new };
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
733 ```
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
734
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
735 * Use the method notation when invoking methods:
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
736
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
737 ```
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
738 -- bad
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
739 my_object.my_method(my_object)
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
740
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
741 -- good
9939
3a7f822f6edd doc/coding_style: apply consistent semi-colon usage
marc0s <marcos@tenak.net>
parents: 9900
diff changeset
742 my_object:my_method();
9858
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
743 ```
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
744
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
745 > **Rationale:** This makes it explicit that the intent is to use the function as a method.
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
746
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
747 * Do not rely on the `__gc` metamethod to release resources other than memory.
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
748 If your object manage resources such as files, add a `close` method to their
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
749 APIs and do not auto-close via `__gc`. Auto-closing via `__gc` would entice
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
750 users of your module to not close resources as soon as possible. (Note that
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
751 the standard `io` library does not follow this recommendation, and users often
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
752 forget that not closing files immediately can lead to "too many open files"
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
753 errors when the program runs for a while.)
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
754
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
755 > **Rationale:** The garbage collector performs automatic *memory* management,
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
756 dealing with memory only. There is no guarantees as to when the garbage
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
757 collector will be invoked, and memory pressure does not correlate to pressure
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
758 on other resources.
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
759
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
760 ## File structure
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
761
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
762 * Lua files should be named in all lowercase.
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
763
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
764 * Tests should be in a top-level `spec` directory. Prosody uses
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
765 [Busted](http://olivinelabs.com/busted/) for testing.
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
766
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
767 ## Static checking
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
768
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
769 All code should pass [luacheck](https://github.com/mpeterv/luacheck) using
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
770 the `.luacheckrc` provided in the Prosody repository, and using miminal
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
771 inline exceptions.
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
772
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
773 * luacheck warnings of class 211, 212, 213 (unused variable, argument or loop
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
774 variable) may be ignored, if the unused variable was added explicitly: for
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
775 example, sometimes it is useful, for code understandability, to spell out what
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
776 the keys and values in a table are, even if you're only using one of them.
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
777 Another example is a function that needs to follow a given signature for API
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
778 reasons (e.g. a callback that follows a given format) but doesn't use some of
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
779 its arguments; it's better to spell out in the argument what the API the
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
780 function implements is, instead of adding `_` variables.
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
781
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
782 ```
9939
3a7f822f6edd doc/coding_style: apply consistent semi-colon usage
marc0s <marcos@tenak.net>
parents: 9900
diff changeset
783 local foo, bar = some_function(); --luacheck: ignore 212/foo
3a7f822f6edd doc/coding_style: apply consistent semi-colon usage
marc0s <marcos@tenak.net>
parents: 9900
diff changeset
784 print(bar);
9858
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
785 ```
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
786
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
787 * luacheck warning 542 (empty if branch) can also be ignored, when a sequence
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
788 of `if`/`elseif`/`else` blocks implements a "switch/case"-style list of cases,
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
789 and one of the cases is meant to mean "pass". For example:
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
790
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
791 ```lua
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
792 if warning >= 600 and warning <= 699 then
9939
3a7f822f6edd doc/coding_style: apply consistent semi-colon usage
marc0s <marcos@tenak.net>
parents: 9900
diff changeset
793 print("no whitespace warnings");
9858
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
794 elseif warning == 542 then --luacheck: ignore 542
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
795 -- pass
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
796 else
9939
3a7f822f6edd doc/coding_style: apply consistent semi-colon usage
marc0s <marcos@tenak.net>
parents: 9900
diff changeset
797 print("got a warning: "..warning);
9858
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
798 end
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
799 ```
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
800
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
801 > **Rationale:** This avoids writing negated conditions in the final fallback
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
802 case, and it's easy to add another case to the construct without having to
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
803 edit the fallback.
54147de1d1b1 doc/coding_style.{txt,md}: Update coding style guide
Matthew Wild <mwild1@gmail.com>
parents:
diff changeset
804