Calling ':Destroy()' method in a child class doesn't do anything

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#1

Hi this is my first time creating game using OOP approach and i have stumble across this problem that i can’t find the solution in dev forum.

so lets say that i have a class called Object:

local Object = {}
Object.__index = Object


function Object.new(Name,Health)
	local NewObject = setmetatable(
		{
			Name = Name,
			Health = Health,
			Died = "create a signal using signal module"
			
		},Object)
	
	return NewObject
end

function Object:Destroy()
	setmetatable(self,nil)
	self = nil
	print(self) -- it print nil
end


return Object

and a child class called Tree:

local Object = require(script.Parent.Object)

local Tree = {}
Tree.__index = Tree
setmetatable(Tree,Object)

function Tree.new()
	local NewTree = setmetatable(Object.new("Tree",5),Tree)
	return NewTree
end

function Tree:OnDied()
	-- do some animation or something
	self:Destroy()
	print(self) -- doesn't print nil
end


return Tree

as i mentioned above when i called the method “:Destroy()” from that child class it doesn’t print nil, can anyone explain to me what’s happening here? or you can suggest me other approach.

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#2

That’s because self is the Tree module not the Object module and you have set the self = nil on the Object module, so it wont replicate on the Tree module unless if you have done it on a local/server script like this:

local Tree = require(script.Tree)
local object = require(script.Object)

local newTree = object.new("Tree", 5)
newTree:Destroy()

Or you can just do something like this on the Tree module since what your doing is a module script to module script.

function Tree:OnDied()
	self = self:Destroy()
	print(self) -- should definitely return a nil because you are not returning anything.
end

I don’t know how I can explain it to you properly of why it’s not printing a nil on your code, all I am saying is that you already have set the metatable on the Tree.new() so it wont replicate everything on the table like setting the self:Destroy() of course its not gonna print nil.

#3

alright so why is this:

local Tree = require(script.Tree)
local object = require(script.Object)

local newTree = object.new("Tree", 5)
newTree:Destroy()
print(newTree) -- print empty table instead of nil

to be more clear i want to delete unused metatable after the instance inside that metatable destroyed so it wouldn’t caused memory leaks. why i want it to be nil? because there is other module script called object manager that hold reference to objects.

#4

You could try :Remove() instead of :Destroy()

#5

If you really want to remove all the data on the module why not just do it on the same module:

function Tree:OnDied()
	for key, _ in self do
		self[key] = nil -- this will print {} after the for loop ends
	end
	self = nil -- or just set it to nil
end
#6

Huh. Renaming the function won’t change anything.

#8

That’s off topic, it does not matter what type of function name you use as long as you understand what the function does.

#12

i just dont want to copy paste the same function to other module script such as: Log,Rock,Grass,etc.

#14

Why not just do something like this:

local Object = require(script.Parent.Object)
local Tree = {}

function Tree.new()
	local self = Object.new("Tree", 5)
	
	function self:OnDied()
		self:Destroy()
	end
	
	return self
end

return Tree

Still works the same way

#15

Their reply was irrelevant, this is regarding a custom Destroy() method for a custom class implementation.

1 Like