What is self and what does self do?

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#1

I keep seeing people use self, and Im very confused on why and how self works.

And what instances should I use self in?

#2
#3
#4

There are A LOT of this same exact question and A LOT of videos for it, although here is a simple explanation…
Lets say you have a function which prints something

local module = {}

function module.abc(...)
	print(...)
end

Now there is 2 ways to use this function

module.abc("a") --prints a

module:abc("a") --prints tableX000 and a

What is this supposed to do with self, and why does it print TableX0000,
Well, if you see the ways we called the function,
The first one was . which printed ONLY what you gave, the second one is : which printed what you gave + TableX0000

When using the : it passes self to the function, which in this case is the module (table) thats why it printed the table name.

This is just a simple explanation if you have any questions feel free to ask

#5

What is self though? what values does it hold / inherit

#6

Lets say you have a module to make card or something, for this you use metatables:

local car = {}
car.__index = car

function car.new(brand, color)
    local newCar = {}
    setmetatable(newCar, car)

    newCar.Brand = brand
    newCar.Color = color

    return newCar
end

return car

Now, in your reg script you would require the module script, then make a new car like this: carModule.new("Lamborghini", "Green")

Now you wanna make a function that you can call on your myCar variable to change the color, like this:
myCar:ChangeColor("Blue")

In this case in your module you’ll do something like this:

function car:ChangeColor(newColor)
    self.Color = newColor
end

So when you call the function on myCar variable, self will be myCar

Full module:

local car = {}
car.__index = car

function car.new(brand, color)
    local newCar = {}
    setmetatable(newCar, car)

    newCar.Brand = brand
    newCar.Color = color

    return newCar
end

function car:ChangeColor(newColor)
    self.Color = newColor
end

return car

Important note: self only exists within methods using the :functionName

Hopefully this cleared things up!

2 Likes
#7

Does car.__index = car make it so that anything that tries to check if a nil value “car” is avaliable, its parent would be in the table?

#8

No, this is used when you use metatables, it is a metamethod, it basically means that when ever you make a metatable like we did here:

That it will inherit all the indexes and functions from car.

For more information look up .__index and metamethods

#9

Im a bit confused, when should you use setmetatable, do you need to use it at the beginning of a script?

Does it connect two tables? and which one is the actual metatable?

So all of the values in the table?

Which one is the metatable? newCar or Car?

#10

newCar is the metatable, it has all the functions and items that car has + its own.

Here is a really great article on metatables and metamethods:

#11

No, but you can. You use setmetatable whenever you want to, well, create a new metatable. In our case we used it when making a newCar so that every new car has everything a car has aswell as it’s own things, and also we can do stuff like what we did with the :ChangeColor function.

Yes, as mentioned in the article I linked in my previous reply: you can think of a metatable, as a normal table that holds configurations/settings for another table that let’s you change the behaviour of that other table. In short, metatables help add more functionalities to a table.

@StarJ3M

1 Like
#12

in the example i gave, self is the module (table) so ANYTHING inside it will be as a “part” of self, if you have a number called abc then self.abc will return the same value and so on

#13

@StarJ3M, did you forget this topic?