Lua

Homepage: Lua
Package manager: LuaRocks
Opinionated code formatter: StyLua

Installing Link to heading

sudo apt update
sudo apt install lua5.4 luarocks

Learning Link to heading

What is `.busted` file? Link to heading

Configuration file for Busted framework.

What is Busted? Link to heading

busted is a unit testing framework with a focus on being easy to use

What is `*.rockspec` file? Link to heading

Rockspec format describes a Lua package (or Lua rock) that can be installed using LuaRocks.

What is a table? Link to heading

Data structure that represents arrays, dictionaries, and other complex data structures.

Comparison:

	Lua	Python	JavaScript
Keys	Any type except `nil` (including other tables)	Immutable types (e.g., strings, numbers, tuples)	Strings or symbols
Values	Any type	Any type	Any type
Definition syntax	`local x = {a = 1, b = 2, c = 3}`	`x = {'a': 1, 'b': 2, 'c': 3}`	`const x = {a: 1, b: 2, c: 3};`
Set value syntax	`x.d = 4` or `x['d'] = 4`	`x['d'] = 4`	`x.d = 4;` or `x['d'] = 4`
Get value syntax	`x.d` or `x['d']`	`x['d']`	`x.d;` or `x['d']`

What is `local M = {}`? Link to heading

local M = {} is a pattern to create and manage a module in Lua, providing encapsulation and a clear structure for defining and exporting functionality.

How it works: initializes an empty table M that will be used to collect functions and variables that will be a part of the module’s interface. local ensures that M is scoped to the module file, preventing it from being accessed globally. This is good practice to avoid polluting the global namespace and potential name conflicts.

M table is returned at the end of the script.

-- <moduleName>.lua
local M = {}

function M.sayHello()
 print("Hello, world!")
end

local function privateFunction()
 -- This function is not added to M and remains private to the module
end

return M

-- main.lua
require('<moduleName>').sayHello()
-- Hello, world!
require('<moduleName>').privateFunction()
-- stdin:1: attempt to call a nil value (field 'privateFunction')
-- stack traceback:
--        stdin:1: in main chunk
--        [C]: in ?