在尝试创建一个非常简单的类继承时,所有对象似乎都在共享相同的值
这是我的代码的简化:
--Generic class
Object = {}
function Object:new (type,id,name)
o = {}
self.type = type or "none"
self.id = id or 0
self.name = name or "noname"
self.direction = "down"
self.animations = {}
self.animations.stack = {}
self.animations.idle = {}
self.animations.idle[self.direction] = {}
setmetatable(o, self)
self.__index = self
return o
end
function Object:draw(x,y)
local img = self.animations.idle["down"][0]
print("drawing " ..self.name.." as "..img)
end
function Object:setimg(img)
self.animations.idle["down"][0] = img
end
Player = Object:new()
-- Player class
function Player:new(id,name)
local o = self
o.id = id or 0
o.name = name or "noname"
o.collision = {}
o.collision.type = "player"
return o
end
function Player:move(x,y)
print("moving to ",x,y)
end
-- Testing
blockimg = "block.png"
grassimg = "grass.png"
plyrimg = "player.png"
block = Object:new("solid",1,"block")
block:setimg(blockimg)
grass = Object:new("floor",3,"grass")
grass:setimg(grassimg)
player = Player:new(1, "plyr1")
player:setimg(plyrimg)
block:draw() -- >drawing grass as player.png
grass:draw() -- >drawing grass as player.png
player:draw()-- >drawing plyr1 as player.png
由于玩家:setimg是最后一次调用,所有“对象”都以plyrimg结束,因此它们不是唯一的
答案 0 :(得分:2)
每次创建新的Object实例时,此函数都会在共享Object表上创建或覆盖属性。
function Object:new (type,id,name)
o = {}
self.type = type or "none"
self.id = id or 0
self.name = name or "noname"
self.direction = "down"
self.animations = {}
self.animations.stack = {}
self.animations.idle = {}
self.animations.idle[self.direction] = {}
setmetatable(o, self)
self.__index = self
return o
end
如果您希望它们是唯一的,则需要在每个新实例上创建这些属性。否则,Object:setimg
将查找索引链以查找animations
,并将图像放在共享属性中。
function Object:new (type,id,name)
local o = {}
-- ...
o.animations = {} -- Or in Player:new
-- ...
self.__index = self
return setmetatable(o, self)
end
答案 1 :(得分:0)
如果您只是将自己传递给构造函数,则可以避免很多问题。我通常会定义这样的类:
local class={x=0,y=0}
local _class={__index=Class}
-- I like prefixing metatables with _, but that's just a personal thing
class.new(x, y)
return setmetatable({x=x, y=y}, _class)
end
class:print() print(self.x, self.y) end
class.sub(sub) return getmetatable(sub)==_class end
这假设类要么在自己的文件中,要么在do
块中,以保持局部变量对除了类及其闭包之外的任何内容隐藏。
您可以在github上的lua文档中阅读更多相关内容。