rawget是為了繞過__index而出現的，直接點，就是讓__index方法的重寫無效。(我這裡用到"重寫"二字，可能不太對，希望能得到糾正)

Window = {}

Window.prototype = {x = 0 ,y = 0 ,width = 100 ,height = 100,}
Window.mt = {}
function Window.new(o)
	setmetatable(o ,Window.mt)
	return o
end
Window.mt.__index = function (t ,key)
	return 1000
end
Window.mt.__newindex = function (table ,key ,value)
	if key == "wangbin" then
		rawset(table ,"wangbin" ,"yes,i am")
	end
end
w = Window.new{x = 10 ,y = 20}
print(rawget(w ,w.wangbin))
 

但是rawset呢，起什麼作用呢?我們再來執行一段程式碼。

Window = {}
Window.prototype = {x = 0 ,y = 0 ,width = 100 ,height = 100,}
Window.mt = {}
function Window.new(o)
	setmetatable(o ,Window.mt)
	return o
end
Window.mt.__index = function (t ,key)
	return 1000
end
Window.mt.__newindex = function (table ,key ,value)
	table.key = "yes,i am"
end
w = Window.new{x = 10 ,y = 20}
w.wangbin = "55"