lua实现多继承

http://my.oschina.net/u/156466/blog/401576
local class1 = {}
function class1:new()
    local obj = {}
    setmetatable(obj, {__index= class1})
    return obj
end

function class1:print1()
    print("class1:print()")
end

function class1:print2()
    print("class1:print()")
end

local class2 = {}
function class2:new()
    local obj = {}
    setmetatable(obj, {__index= class2})
    return obj
end

function class2:print2()
    print("class2:print()")
end

local class3 = {}
function class3:new()
    local obj = {}
    setmetatable(obj, {__index= class3})
    return obj
end

function class3:print2()
    print("class3:print()")
end

function class3:print3()
    print("class3:print()")
end

function super(k, list)
    for i,v in ipairs(list) do
        local ret = v[k]
        if ret then
            return ret
        end
    end
end

local class = {}
function class:new(...)
    local obj = {}
    -- local  base = {class1, class2}
    local base = {...};
    --t为调用的对象,k为方法名
    setmetatable(class, {__index= function(t,k) return super(k, base) end})
    setmetatable(obj, {__index = class})
    return obj
end

local c = class:new(class2,class1,class3);
-- c:print1();
c:print2();
-- c:print3();