Lua Class Class

--[[

class.lua
Version: 1.0.3

Author: MegaLoler
Email: megaloler9000@gmail.com

Contains functions for easily defining and instantiating classes in Lua.

First make sure you have this in your code:
require("class.lua")

Define a new class with the newClass() function:
NewClass = newClass()

Instantiate an new instance of the class with the new() method:
newInstance = NewClass:new()

Add methods to the class like this:
function NewClass:newMethod()
    print("New method")
end

Call methods of an instance of a class like this:
newInstance:newMethod() -- prints "New method"

Add a constructor to the class like this:
function NewClass:init()
    print("New instance created")
end

newInstance2 = NewClass:new() -- prints "New instance created"

Use constructor parameters like this:
function NewClass:init(par)
    print("New instance: " .. par)
end

newInstance3 = NewClass:new("hello") -- prints "New instance: hello"

Create subclasses like this:
Subclass = newClass(NewClass)

subclassInstance = Subclass:new("hi") -- prints "New instance: hi"

Get the class of an instance like this:
subclassInstance:getClass()

Get the superclass of an instance like this:
subclassInstance:getSuperClass()

Call a method of a superclass that has been overridden in its subclass like this:
subclassInstance:getSuperClass():originalMethod()

--]]

function newClass(parent)
    local class = {} -- Method table
    if Class then -- Class class doesn't inherit from anything
        setmetatable(class, {__index = parent or Class}) -- Inherit from parent, Class by default
    end
    return class
end

Class = newClass() -- Create Class class

function Class:new(...) -- Class constructor
    local instance = setmetatable({}, {__index = self})
    instance:init(...)
    return instance
end

function Class:init() -- Instance constructor
end

function Class:getClass()  -- Returns the class of an instance
    if Class == self then return nil end
    return getmetatable(self).__index
end

function Class:getSuperClass()  -- Returns the superclass of an instance
    return self:getClass():getClass()
end