What is self used for?

Help and Feedback Scripting Support
#1

So I was expermenting with Luau and I created this script below:

type car = {speed:number, model:string, dimensions:number, safe:boolean}

local honda = {speed=42, model="civic", dimensions=43, safe=true}
local truck = {speed=34, model="mack", dimensions=58, safe=false}

local car = {}

function car:GetSpeed(self)
	self.speed = 40
	return self.speed
end

print(car:GetSpeed(honda))

The topic of my concern is the function. So self is highlighted, meaning its special, but to me its just looks like any old param. If I replace “self” with “foo” or “bar”. The same results will print out aka 40.

#2

self is the first argument passed when relating to Object Oriented Programming

#3

self is an implicit parameter that is passed when you use the : notation to call functions on tables.

so

a:b(...)

is sugar for

a.b(a, ...)

and

function a:b(...)

end

is sugar for

function a.b(self, ...)

end

The implicit parameter doesn’t have to be called self though, and when using : you don’t pass it in yourself.

#5

So if I do that function,

function car:GetSpeed()
	self.speed = 40
	return self.speed
end

So what I am getting is that no parameter = self?

#6

function car:GetSpeed() is the same as function car.GetSpeed(self).

It is implicit.

#7

So the above code will work right? ^ ^ ^

#8

Test it, and you will see

tl;dr yes

#9

Quick unrelated question: Can you use Luau in plugins?

1 Like
#10

Sorry for the late response, yes. You can ONLY use Luau for plugins in fact.

Btw I bumped this because, I still am not sure what self is useful to?? I don’t see examples of anyone really using it. Can someone give some examples?