[Lua]用__index/__newindex来限制访问

网友问了一个问题,说对象A在内部可以修改HP.外部对象只能访问对象A的HP,不能修改.

这东西其实可以用__index和__newindex来实现.

__index指向对象A,这样就可以访问;

__newindex重写,修改hp的话,就禁止.就可以完成他的需求.

下面给出简单的代码:

复制代码function cannotModifyHp(object) local proxy = {} local mt = { __index = object, __newindex = function(t,k,v) if k ~= "hp" then object[k] = v end end } setmetatable(proxy,mt) return proxy end object = {hp = 10,age = 11} function object.sethp(self,newhp) self.hp = newhp end o = cannotModifyHp(object) o.hp = 100 print(o.hp) o:sethp(111) print(o.hp) object:sethp(100) print(o.hp)

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
function cannotModifyHp(object)
    local proxy = {}
    local mt = {
    	__index = object,
	__newindex = function(t,k,v)
	    if k ~= "hp" then
		object[k] = v
	    end
	end
    }
    setmetatable(proxy,mt)
    return proxy
end

object = {hp = 10,age = 11}
function object.sethp(self,newhp)
	self.hp = newhp
end

o = cannotModifyHp(object)

o.hp = 100
print(o.hp)

o:sethp(111)
print(o.hp)

object:sethp(100)
print(o.hp)

PS:

好长时间没写过lua了,都快忘了