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STYLE.LUA(9) Kernel Developer's Manual STYLE.LUA(9)


style.luaFreeBSD lua file style guide


This file specifies the preferred style for lua source files in the FreeBSD source tree. Many of the style rules are implicit in the examples. Be careful to check the examples before assuming that style.lua is silent on an issue.

The copyright header should be a series of single-line comments. Use the single-line comment style for every line in a multi-line comment.

After any copyright header, there is a blank line, and the $FreeBSD$ comment for non-C/C++ source files.

The preferred method of including other files and modules is with (name), such as:

-- $FreeBSD: releng/12.2/share/man/man9/style.lua.9 333419 2018-05-09 16:52:28Z kevans $

config = require("config");
menu = require("menu");
password = require("password");
-- One blank line following the module require block

() is generally avoided.

Indentation and wrapping should match the guidelines provided by style(9). Do note that it is ok to wrap much earlier than 80 columns if readability would otherwise suffer.

Where possible, (...) is preferred to (s, ...). This is applicable to objects with methods. String are a commonly-used example of objects with methods.

Testing for nil should be done explicitly, rather than as a boolean expression. Single-line conditional statements and loops should be avoided.

local variables should be preferred to global variables in module scope. internal_underscores tend to be preferred for variable identifiers, while camelCase tends to be preferred for function identifiers.

If a table definition spans multiple lines, then the final value in the table should include the optional terminating comma. For example:

-- No terminating comma needed for trivial table definitions
local trivial_table = {1, 2, 3, 4}

local complex_table = {
		id = "foo",
		func = foo_function, -- Trailing comma preferred
		id = "bar",
		func = bar_function,
	},	-- Trailing comma preferred

This reduces the chance for errors to be introduced when modifying more complex tables.

Multiple local variables should not be declared initialized on a single line. Lines containing multiple variable declarations without initialization are ok. Lines containing multiple variable declarations initialized to a single function call returning a tuple with the same number of values is also ok.

Initialization be done at declaration time as appropriate.




This manual page is inspired from the same source as style(9) manual page in FreeBSD.

February 25, 2018 Debian