Window = {}

Window.prototype = {x = , y = , width = , height = }

Window.mt = {}

function Window.new(o)

    setmetatable(o, Window.mt)

    return o

end

--[[Window.mt.__index = function (table, key)

    return Window.prototype[key]

end--]]

Window.mt.__index = Window.prototype--当我们想不通过调用__index metamethod来访问一个表，我们可以使用rawget函数，

w = Window.new{x = , y = }

print(w.width)