I need help with detecting when a table changes

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#1

local Table = {
coins = 0,
gems = 0
}

How would i detect when the coins changes?

#2

Here’s a script that should help you:

local ReplicatedStorage = game:GetService("ReplicatedStorage")
local Coins = Instance.new("NumberValue")
local Gems = Instance.new("NumberValue")
local CurrencyFolder = Instance.new("Folder")

CurrencyFolder.Name = "CurrencyFolder"
CurrencyFolder.Parent = ReplicatedStorage

Coins.Value = 0
Coins.Name = "Coins"
Coins.Parent = ReplicatedStorage:WaitForChild("CurrencyFolder")

Gems.Value = 0
Gems.Name = "Gems"
Gems.Parent = ReplicatedStorage:WaitForChild("CurrencyFolder")

local Table = {
    Coins.Value;
    Gems.Value;
}

Coins.Changed:Connect(function(val)
    print(string.format("The coins value was changed to %s", val))
end)
#3

I have tried this however i am specifcally trying to do it through just a script, I heard about meta tables but just trying to find a simpler way.

#4

metatable's would work, however you cannot detect if a value is changed in them. Above is the simplest way to do it, you can even remove some code if you create the values manually.

#5

One way, without metatables is to define getter/setter functions. The purpose of these functions is to act as wrappers for table accesses & assignments.

local Stats = {
	Coins = 0,
	Gems = 0
}

local function GetStat(StatName)
	return Stats[StatName]
end

local function SetStat(StatName, StatValue)
	Stats[StatName] = StatValue
	return StatName
end

A metatable implementation would require the use of a proxy table, take a look at the following example.

local Stats = {Coins = 0, Gems = 0}
local StatsProxy = {}
setmetatable(StatsProxy, {__newindex = function(Table, Key, Value)
	if not Stats[Key] then return end
	Stats[Key] = Value
	print(Key.." stat changed to "..Value..".")
end})

StatsProxy.Coins = 5
print(Stats.Coins) --5

For further information about ‘proxy’ tables, check out the following resources.
https://www.lua.org/pil/13.4.4.html
https://www.lua.org/pil/13.4.5.html

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