Metatables/metamethods usage

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#1
  1. What do you want to achieve? An explanation on metatables/metamethods where could those be used, because i dont see a practical usage. Would be nice if you included some quick examples.
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#2

Metatables are complicated to use if you are new it.
We cant really explain in 3 lines how to use them.
So here this helped me a lot:

#3

They allow you to make classes, allow you to make your code look like hacker code, it makes your code look super complicated, they allow you to do weird things like this

name_of_a_table(some_arguments)

,

name_of_a_table + name_of_a_table

and much, much more…

It also helps make your code more organized, and clean.

It’s also really something you should know because some game dev studios on roblox will only hire you if you know oop, metatables, and everything like that.

I accidentally hit reply before I was done writing my reply!

#4

Okay, let’s say you wanted to work with Vectors and thought you wanted to make a game in the 4th dimension.

Roblox doesn’t have Vector4 so we can make one ourselves. Vector3 and Vector2 can be added, subtracted, divided, multiplied, tostringed. Now if we have to have out Vector4 to be able to do that too we.can

--Module
function Vector4._mul()
    -- Vector multiplication code goes here
end

-- Script

-- That means we can do something like this

local Vec = Vector4.new(1,2,3,4)

local ReturnVec = Vec * Vec

To put it simply

They may be mistakes Inthe code

#5

Here’s the truth I’ve come to about metatables. I find myself using them in very exclusive circumstances. Luau generally has alternatives, and you can mostly get by without them depending on your team’s code practices.

The concept to open with is that every table can have a metatable, and multiple tables can attach to the same metatable. Metatables perform tasks on other tables.

AngledAxis has listed some great resources to learn from, but here’s one more from the actual Lua website.

I’ll give you a relatively practical example of one being used by explaining how you can write custom classes in modules.

Let’s say that you’re making a game, and in that game you need to be able to create objects effectively that hold their properties and could reference one another. You would start by making a module.

local MyMod = {}
return MyMod

Ideally, you will need to be able to construct objects through this module, so we would write a constructor function.

local MyMod = {}
MyMod.__index = MyMod

MyMod.new = function(...)
	local ThisIndex = {}
	setmetatable(ThisIndex, MyMod)
	
	return ThisIndex
end

return MyMod

In the above code, we have wrote a very basic constructor. Here is what actually happens:

→ The __index metamethod, as an example, will be fired every time Lua tries to reach a nil value in a table. So, here we write __index to get MyMod for a nil index. This is helpful because MyMod will have our functions wrote into it. From your script, assigning a variable to your newly created object becomes as simple as local NewObj = MyMod.new(params) (provided MyMod module has been required).

→ We set a metatable for ThisIndex & MyMod so that a nil index on our object (possibly a future function we might write), will index MyMod as well, giving you access to all of the functions that you assign to it. This way you can have individual objects with their own unique properties and interactions, all in a very organized manner.

Here is a list of all meta-methods, for your general curiosity. Hopefully through this example you can think of certain ways that these would be useful. The best way to actually learn metatables is to hop into Studio and practice them. Some good resources have been posted in this thread.

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#6

it really does make your code look like a minecraft enchantment book

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#7

ok guys thank you for your replies ill check them out later in my free time