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Advanced Lua Programming

Master complex Lua techniques for high-performance Roblox game development

Course Contents

Advanced Lua Concepts

Metatables are Lua's powerful mechanism for customizing object behavior. They allow you to define how objects respond to operations like addition, indexing, and comparison.

metatables.lua
-- Create a custom vector type with operator overloading
local Vector = {}
Vector.__index = Vector

function Vector.new(x, y)
  return setmetatable({x = x or 0, y = y or 0}, Vector)
end

function Vector:__add(other)
  return Vector.new(self.x + other.x, self.y + other.y)
end

function Vector:__mul(scalar)
  return Vector.new(self.x * scalar, self.y * scalar)
end

function Vector:magnitude()
  return math.sqrt(self.x * self.x + self.y * self.y)
end

-- Create and operate on vectors
local v1 = Vector.new(3, 4)
local v2 = Vector.new(1, 2)
local v3 = v1 + v2 -- Uses __add metamethod
local v4 = v3 * 2  -- Uses __mul metamethod

print("Metatable magic: " .. v4:magnitude())

Common Metamethods

  • __index: Controls access to missing keys in tables
  • __newindex: Controls writing to missing keys
  • __add, __sub, __mul, __div: Arithmetic operations
  • __eq, __lt, __le: Comparison operations
  • __call: Calling a table like a function