-- functions.lua
function class(classname, super)
    local superType = type(super)
    local cls


    if superType ~= "function" and superType ~= "table" then
        superType = nil
        super = nil
    end

    if superType == "function" or (super and super.__ctype == 1) then
        -- inherited from native C++ Object
 

        cls = {}

        if superType == "table" then
            -- copy fields from super
            for k,v in pairs(super) do cls[k] = v end
            cls.__create = super.__create
            cls.super    = super
        else
            cls.__create = super
            cls.ctor = function() end
 

        end

        cls.__cname = classname
        cls.__ctype = 1

        function cls.new(...)
            local instance = cls.__create(...)
            -- copy fields from class to native object
            for k,v in pairs(cls) do instance[k] = v end
            instance.class = cls
            instance:ctor(...)
            
 
return instance
        end

    else
        -- inherited from Lua Object
        if super then
            cls = {}
            setmetatable(cls, {__index = super})
            cls.super = super
        else
            cls = {ctor = function() end}
        end

        cls.__cname = classname
        cls.__ctype = 2 -- lua
        cls.__index = cls

        function cls.new(...)
            local instance = setmetatable({}, cls)
            instance.class = cls
            instance:ctor(...)
            return instance
        end
    end

    return cls
end

- 兩個類組合

1、建立class room 只需要require functuins.lua 即可

require "functions"
local room = class("room")

function room:ctor(room_id)
    -- 需要的變數
    local success, room_sink_creator = pcall(require, "room_sink") 
    if success then
        self.sink = room_sink_creator.new(self) -- 把self傳入
    end
end

-- 這裡就可以呼叫 self.sink:function
function room:test_sink_func()
    if self.sink and self.sink.func then
        self.sink:func()
    end
end
function room:func()
　　print("room func call")
end

2、建立class room_sink

require "functions"

local room_sink = class("room_sink")

function room_sink:ctor(room)
    self.room = room
    -- 其他資料    
end

function room_sink:func()
    print("room_sink func() call")
end

-- 這裡可以呼叫 room裡的方法
function room_sink:test_room_func()
     self.room:func()   
end

這裡建立了兩個類 room 和 room_sink，這裡有一個很特殊的地方，room可以呼叫room_sink 的方法，同時room_sink 也可以呼叫room的方法。(這裡room和room_sink 並不是繼承關係 而是組合)

- 繼承

1、建立基類 room

require "functions"
local room = class("room")

function room:ctor(room_id)
    -- 需要的變數
    self.room_id = room_id
end

function room:func()
　　print("room func call")
end

2、建立派生類

require "functions"

local room = require "room"
local room_sink = class("room_sink", room)

function room_sink:ctor(room)
    self.room = room
    -- 其他資料    
end

-- 重寫基類方法
function room_sink:func()
    print("room_sink func() call")
end