How do i use __newindex?

Help and Feedback Scripting Support
#1

Looked at other posts and ion really get it
i have this code

local BulletFolder = game.ReplicatedStorage.Bullets
local NormalBullet = BulletFolder.NormalBullet

local GunInformation = {
	["Glock_Test"] = {
		["Distance"] = 300,
		["Damage"] = 12,
		["MagSize"] = 14,
		["UsedBullet"] = NormalBullet
	},
	["Ak47_Test"] = {
		["Distance"] = 450,
		["Damage"] = 24,
		["MagSize"] = 30,
		["UsedBullet"] = NormalBullet
	}
}

GunInformation.GetInformation = function(Gun)
	if GunInformation[Gun.Name] then
		return GunInformation[Gun.Name]
	else
		return nil
	end
end



GunInformation.__index = GunInformation
return GunInformation

and i want to make it so instead of this

GunInformation.GetInformation = function(Gun)
	if GunInformation[Gun.Name] then
		return GunInformation[Gun.Name]
	else
		return nil
	end
end

its just this

GunInformation.GetInformation = function(Gun)
	return GunInformation[Gun.Name]
end

and have it so if its not a vaild “gun” then it will default to “Glock_Test”
no clue how to use __newindex for this as i OOP is still very confusing to me

#2

I’ll explain __newindex:

local meta = {
__newindex = function(self, index, value)
self[index] = value * 2
end
}
local tb = setmetatable({}, meta)
tb[1] = 1
print(tb[1]) -- > 2

__newindex is a function that can possibly modify a modification or a newly inserted value. In this case, we will set the index normally but multiply the value times to, hence the value * 2. When setting the index to 1 and the value to 1, the __newindex metamethod will interpret that before it’s actually set and will change the value, multiplying it by 2 before actually creating the new index.

In this case, you actually don’t want to use __newindex and you just want to use __index. This method can either be a separate table or function to return an index.

For your case, if you want to implement a default weapon, set this as your __index metamethod:

function(object, key)
return GunInformation.Glock_Test
end

but of course, you can just use an or operator:

local gun = GunInformation[Gun.Name] or GunInformation.Glock_Test

which I believe is the simpler option.

1 Like
#3

Oh, i got the indexes mixed up

I probably messed somethign up but i tried doign

-- Module

local GunInformation = {
	["Glock_Test"] = {
		["Distance"] = 300,
		["Damage"] = 12,
		["MagSize"] = 14,
		["UsedBullet"] = NormalBullet
	},
	["Ak47_Test"] = {
		["Distance"] = 450,
		["Damage"] = 24,
		["MagSize"] = 30,
		["UsedBullet"] = NormalBullet
	}
}

GunInformation.GetInformation = function(Gun)
	return GunInformation[Gun.Name]
end



GunInformation.__index = function(A, B)
	return "D"
end

return GunInformation

and

-- Server
local Thingy = require(game.ServerScriptService.GunInformation)
print(Thingy.GetInformation("d"))

it printed nil, no clue what i did wrong :smiley:

yeah but if i get some sort of information on whatever OOP is then maybe it will be less of a pain to understand?

#4

OOP or Object Oriented Programming is a type of programming that allows you to focus methods and variables around objects. Here’s an example of how to create an OOP car:

local manufacture = {}

function manufacture.new(carModel, carColor, carYear)
local car = {
Year = carYear,
Model = carModel,
Color = carColor
}
return car
end
return manufacture

This OOP car function does not contain any methods. Your code does not contain methods or objects that are created, so it is not OOP yet. I recommend researching OOP before you continue. though it might be a bit of a handful

#5

i’ve looked at many tutorials, explainations, ect.
None of it goes over the advanced stuff i see in big module scripts (it may of actually gone over some of it, but didnt go too deep into explaination about it) and stuff, plus with what ive seen from these said tutorials it doesn’t really seem too helpful
(noted that ive only seen __index used to do stuff like)
Module1

local Tr = {}

function Tr.new(Letter)
	local mtabel = setmetatable({}, Tr)
	mtabel["ChosenLetter"] = Letter
	return mtabel
end

function Tr:AddLetter(Letter)
	Tr["AddedLetter#" .. #Tr - 1] = Letter
end

Tr.__index = Tr
return Tr

Module2

local Fr = {}

function Fr.ChosenNumber(Number)
	local mTable = setmetatable({}, Fr)
	mTable["ChosenNumber"] = Number
	return mTable
end

Fr.__index = require(game.ReplicatedStorage.TrModule)
return Fr

tbh not even sure if i got those correct or not.
too lazy to do the server script forgot to add

#6

Do you really need to use metamethods for this? You can just opt for either returning the gun information dictionary or just

GunInformation.GetInformation = function(Gun)
	return GunInformation[Gun.Name] or GunInformation.Glock_Test
end

Where if GunInformation[Gun.Name] returns nil, the ternary operator will opt for the only value beside the or

#7

No, but im stingy and want to atleast do something with metamethods