What is self? (in the simplest explanation)

[coo1ifyy]

Hello everybody,

I want to know what self is, and I want it in a simple explanation since most explainations are really complicated and don’t make sense to me. I know that it is used in a Module, but that’s it.

[Inkthirsty]

self is used within modules to easily run other functions

[coo1ifyy]

Can I have an example?

aaaaaaaaaaaaaaaaaaaaaaaaaa

[Vanniris (Vanni)]

Self is used in Object Oriented Programming to define the object a method is referred to as its first parameter.

When you call Instance:Destroy(), you’re not inserting any parameters. Within the Destroy method, self is defined as the Instance you’re calling the method on.

Instance:Destroy()

-- Destroy:
function x()
	self.Parent = nil
	-- self is the Instance you called the method on
	return x
end

-- it's the same as in:
x.Destroy(Instance)

function x.Destroy(Instance)
	Instance.Parent = nil
	return x.Destroy
end

Except, Instance is a class, so you can’t name it that way. I’m on mobile so I don’t care.

[mniao]

On the most simple level, self is what the function was called on if the function has :, of course this is combined with __index to basically create classes.

local something = {}

function something:ChangeSomethingOnSomething()
    print(self == something)
    self.someValue = 5
end

[Vanniris (Vanni)]

Just think self as “myself”. When I do the function (method) on myself… I declare my value as this…

[coo1ifyy]

@mniao

print(self == something)

While I was testing out @mniao’s script, that printed true, so would that mean self equals the module?

[coo1ifyy]

So that would mean, Destroy’s function is kind of like this?

function Instance:Destroy()
   self.Parent = nil
end

thisisainstance:Destroy() -- thisisainstance gets parented to nil

---

Because,

function anythingthatwascalledhere:A()
   -- self == anythingthatwascalledhere
end

[mniao]

Yes, on that case we’re only using a table so self is always gonna be equal to it, but here’s how you would normally use self.

local class = {}
class.__index = class --if nothing is found under the table then search on class table

function class.new()
    local self = setmetatable({}, class) --create a new table and set the new table's metatable to class
    return self
end

function class:ChangeSomethingOnSomething()
    print(self == class) --false if called on newObject
    self.someValue = 5
end

local newObject = class.new()
newObject:ChangeSomethingOnSomething()
--[[
Since newObject doesn't have a function called "ChangeSomethingOnSomething",
it will instead search on class, on which case self will be equal to newObject inside the function since
that's what we called the function on.
]]

[anon81993163]

self is self. Referring to the own scope of the table. self by default is nil, until it is moved in a specific table context/scope. Use cases involve interacting with “siblings” in the table.

-- This is the table
local randomTable = {}

-- Function Foo, which prints the param it gets
function randomTable:Foo(message) -- implicit self = randomTable, sugar syntax
    print(message)
end

-- Function Bar, calls self:Foo("Bar!"), subsequently printing "Bar!"
function randomTable:Bar()
    self:Foo("Bar!")
end

-- Calling the function Bar
randomTable:Bar()

[coo1ifyy]

I’ll mark this as the solution, since it was the one that started making me understand what self is. Thanks everyone who helped!