Lua Code Generator

Lua is a lightweight scripting language embedded in many applications. It powers game modding in Roblox and World of Warcraft, game development in Love2D, macOS automation in Hammerspoon, web server scripting in Nginx via OpenResty, and server-side scripting in Redis. Its tiny size and clean C API make it easy to embed in any application.

Lua has no built-in class keyword. Classes are created using tables and metatables. Setting __index on a metatable allows table instances to inherit methods from a parent table. The pattern local MyClass = {} MyClass.__index = MyClass is the foundation of Lua OOP. When you call instance:method(), Lua looks up "method" in the instance table first, then follows __index to the class table.

Lua 5.1 is the base for LuaJIT and Roblox Luau. Lua 5.2 removed the old module system and added bitwise library. Lua 5.3 added native integers and bitwise operators. Lua 5.4 added to-be-closed variables, a generational garbage collector, and a cleaner integer/float split. Each version introduced small breaking changes to the standard library.

LuaJIT is a Just-In-Time compiler for Lua 5.1 that compiles Lua to native machine code at runtime. It is significantly faster than the standard interpreter and is used in game engines, Redis 7+, and high-performance web servers. LuaJIT also provides the FFI library for calling C functions directly from Lua without writing C bindings.

Coroutines are cooperative concurrency primitives in Lua. A coroutine can suspend itself with coroutine.yield() and be resumed later with coroutine.resume(). Only one coroutine runs at a time. coroutine.wrap() creates a coroutine and returns an iterator function that resumes it each time it is called, making it easy to use coroutines in for loops as producers.

Lua uses pcall() (protected call) instead of try/catch blocks. pcall(f, arg1, arg2) calls f with the given arguments and returns true plus any return values on success, or false plus an error message on failure. xpcall() adds a message handler function for stack traces. error() raises an error with a message and optional level number indicating which call in the stack is reported as the error source.

All variables in Lua are global by default unless declared with the local keyword. Global variables are stored in the _G table and are accessible from any scope. Local variables exist only within their enclosing block and are faster to access because the VM resolves them by index rather than hash lookup. Best practice is to always use local for variables unless you explicitly need global access.

Use require("modulename") to load a Lua file. Lua searches package.path for a matching filename (typically modulename.lua). require caches results so the file is executed only once even if required multiple times. For simple single-file inclusion without caching, dofile("path/to/file.lua") re-executes the file every time it is called and returns its return value directly.