Tables Acting as If They're Linked

Bug Reports Engine Bugs
#1

So recently, I encountered an odd issue which was breaking my game (Specifically my GCC game) - players were getting unusual amounts of potions, incorrect amount of candies, and more bugs were occurring.

After doing extensive research (8 hours of debugging and a case of Mountain Dew later), I found that tables now have an odd behavior that may/may not be intentional. If you set a table within a table from a variable that is set as a table, it acts as a pointer instead of a table.

Example:

[spoiler][code]template_playerdata = {
candy=0,
potions=0,
kills=0,
items={a=1,b=2,c=3}

playerdata = {}

game.Players.PlayerAdded:connnect(function(plr)
playerdata[tostring(plr.userId)] = template_playerdata
end)[/code][/spoiler]

Now, the previous behavior was that when you ran this code, each player would get a copy of the template player data that was a copy of the original. Now, the new behavior is that it acts as a pointer directly to the template player data instead of its own separate table. That means that if player 1 gets 10 candies, and player 2 joins after that event occurs, then player 2 will receive the player data of player 1.

I’m not sure if this is intentional or not, but it sure as heck is annoying (I had to write a function to make a copy of the table so it wouldn’t write to the original) - some clarification as to if this is the intended behavior or not would be greatly appreciated.

Thanks!

1 Like
#2

I agree that this should be documented. I always use a function called ‘DeepyCopy()’ to access my data in that kind of cases.

#3

That’s how Lua works.

Strings and numbers pass around the content of themselves, and everything else passes around pointers.

I’m pretty sure it is documented, give me a sec.

“A table is always anonymous. There is no fixed relationship between a variable which holds a table and the table itself.”

#4

[quote] That’s how Lua works.

Strings and numbers pass around the content of themselves, and everything else passes around pointers.

I’m pretty sure it is documented, give me a sec. [/quote]

This used to work a while back, but a recent update caused this behavior.

#5

[quote] That’s how Lua works.

Strings and numbers pass around the content of themselves, and everything else passes around pointers.

I’m pretty sure it is documented, give me a sec. [/quote]

This used to work a while back, but a recent update caused this behavior.[/quote]

That’s weird. Maybe you were doing something different?

#6

It’s always acted this way, I don’t know why you’re seeing something different now, regardless. I think that you should just be setting the table from within your function.

#7

Tables are memory locations. You need to set the contents of the table to a new memory location to get a new table.

#8

A simple way to make a new copy:

function copyTable(tab)
	return {unpack(tab)}
end
1 Like
#9

[quote] A simple way to make a new copy:

function copyTable(tab) return {unpack(tab)} end [/quote]

This only works with numerical indices.
It should be noted that any members of the table that are tables themselves will still be “linked”.

#10

[quote] A simple way to make a new copy:

function copyTable(tab) return {unpack(tab)} end [/quote]

This only works with numerical indices.
It should be noted that any members of the table that are tables themselves will still be “linked”.[/quote]

function duplicateTable(t)
local duplicate = {}
for key,value in pairs(t) do
duplicate[key] = value
end
return duplicate
end