lua 面向对象笔记 继承 和 组合

-- 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

- 两个类组合

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

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

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

-- 这里就可以调用 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、创建class room_sink 

require "functions"

local room_sink = class("room_sink")

function room_sink:ctor(room)
    self.room = room
    -- 其他数据    
end

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

-- 这里可以调用 room里的方法
function room_sink:test_room_func()
     self.room:func()   
end

这里创建了两个类 room 和 room_sink，这里有一个很特殊的地方，room可以调用room_sink 的方法，同时room_sink 也可以调用room的方法。(这里room和room_sink 并不是继承关系 而是组合)

- 继承

1、创建基类 room

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

function room:ctor(room_id)
    -- 需要的变量
    self.room_id = room_id
end

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

2、创建派生类

require "functions"

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

function room_sink:ctor(room)
    self.room = room
    -- 其他数据    
end

-- 重写基类方法
function room_sink:func()
    print("room_sink func() call")
end