Need help figuring out why a list is changing between scenes

[jade echo]

I have class that is shared between scenes through an intermediate object and it seems to be changing in between the Start and Awake callback functions of the object, and i'm not quite sure why.

In the screenshots, notice how in the pic where Awake is highlighted, in the watch window, MuseSensors has 6 items. In the pic where Start is highlighted, it only has 5.

@latent sable

The context is that I have a scene that has an object called Settings and Data (see screenshot)

That object uses this script SceneSettings, which references a static instance of the DataCompanionListener class.

In between the Awake and Start callbacks of SceneSettings, a list in the static instance of DataCompanionListener seems to change, and I don't know why. Any help figuring out why, and how I can stop that from happening, woudl be appreciated.

[latent sable]

Note that "the static instance of the DataCompanionListener class" isn't really a thing

There is no "static instance"

[jade echo]

sorry i misspoke

[latent sable]

there's a static reference variable that is pointing to instances that are very much in scenes

[jade echo]

yes it's a static variable, it's not being instantiated

but my point is

(and idk why this is the case), but the way it was written

scenesettings declares a datacompanionlistener variable

[latent sable]

You were saying this before:

datacomponentlistener is in that scene "directly" declared in the hierarchy. but in a different scene, it's declared a bit differently (illshow the unity editor screnshot one sec)
Can you show what you mean?

[jade echo]

however that isn't being used at all for anything, and instead a static refrence is ocntinually updated

[jade echo]

oh so like here in this scene, there is no datacompanionlistener object declared in the scene

[latent sable]

yeah...

[jade echo]

what i meant by this was just that in this scene, datacompanionlistener is accessed throguh scenesettings

[latent sable]

Well I don't see it "accessed" at all - but yeah it's odd. I would expect that if you have a static instance variable or property, it's essentially a singleton and everything should access it through that variable/property

I don't see any relation to the original question here though

[jade echo]

my core issue here is that there's a member in datacompanionlistener called musesensors

and it's modified between the awake and start callback functions of scenesettings

there's an item in there that gets removed from the end

and i can't figure out why

or how to prevent that

[latent sable]

Well for one are there any scene transitions going on?

if not, the only way that could be happening is if some code is doing it.

so just search the code for references to that list and see what's changing it

[jade echo]

it happens in the midst of a transition into the scene

[latent sable]

So we have to be careful here

let's make sure we're actually talking about the same instance of the script

It would be good to check the InstanceID of the DataCompanionListener in the debugger

[jade echo]

which script? scenesettings or datacompanionlistener?

[latent sable]

DataCompanionListener

[jade echo]

oh kk

[latent sable]

the one that owns the list

[jade echo]

one second

ok so

how do i find the instance id in the watch window?

it doesn't seem to be a property on the datacompanionlistener

[latent sable]

Should be called this

[jade echo]

i cannot find one

right i guess because the instance is null

[latent sable]

So uh

it looks to me like it's not ACTUALLY null

it's Unity's fake null

Which could/would partially explain the issue

[jade echo]

oh i did a thing accidentally btw

[latent sable]

This is what you see when an object was Destroy()ed

[jade echo]

i accidentally set one of those fields to the object id

oen sec

i right clicked and selected set as object id and idk why

one sec

[latent sable]

I think this is maybe a "Rider is doing something cool" thing

m_InstanceID is maybe an unmanaged C++ field

[jade echo]

ok so i fixed the oject id thing

can you explain how you mean by fake null?

[latent sable]

btw when you're in this view you can do DataCompanionListener.Instance.GetInstanceID() in the immediate mode command window thing in the debugger

[latent sable]

When you call Destroy() on a UnityEngine.Object in Unity the object gets marked as destroyed internally an then all your other code will see that myObject == null starts returning true

[latent sable]

even though the ferences are not actually null

[latent sable]

ok cool so now can you see if this instance ID is the same for the two debugger contexts

so we can see if we're even looking at the some object

[jade echo]

ohh kk

[latent sable]

right so we're maybe dealing with two completely different instances of the component here

[jade echo]

so like after SceneSettings.Awake, it invokes DataCompanionListener.Awake

and it looks like after Instance = this, in datacompanionlistener awake

the object is changing

[latent sable]

yeah that's expected

you're changing scenes

the copy of the object in the old scene will have been destroyed

now there's a new one in the new scene

I would start by looking at the two scenes in question and see if there is a DCL in each scene

(at edit time)

[jade echo]

i see ok. let me check soething

[latent sable]

And by the way if you're accessing DCL.Instance from the Awake function in SceneSettings, that can potentially be problematic for this exact reason

A good rule of thumb is to do "self init" in Awake, and then initialization that depends on other scripts being initialized in Start

[jade echo]

How do you mean?

[jade echo]

It looks like theres 2 separate dcl instances?

[latent sable]

yes, Presumably each of the scenes involved has one in it. Which scene are you transitioning from and which are you transitioning into?

[jade echo]

Also why is the list being changed in the second scene? I dont have any logic to remove from the list in question

I have some logic to add to it

[tranquil juniper]

Still not solved?

[jade echo]

A bit closer to the cause

But not quite there yet

[latent sable]

it isn't being changed

There are two lists

they have different contents

[jade echo]

Right but like i don't have any initialization logic for the lists

[tranquil juniper]

why isnt this stuff you need in many scenes in a scriptable object instead?

[jade echo]

I inherited the codebase

[latent sable]

They are likely just set up in the inspector in each scene

[jade echo]

Im trying to make as few changes as I can to fix bugs

[latent sable]

So again - I would just be looking for them in the two scenes and seeing how they are set up in the inspector

[tranquil juniper]

^ search the hierachy using t:MyType

[latent sable]

If the intent is that the list is the same everywhere - you could/should be using a prefab for the object that has this script on it

[jade echo]

First thank you so much for your help with this!!!!!!

[latent sable]

so that you can change it in one place without it getting out of sync

[jade echo]

The wonky thing is that the dcl instance isnt exposed directly in the second scene

[latent sable]

Alternatively - just set it up once in a "bootstrap" scene and make it DDOL

[latent sable]

Well it's coming from somewhere

so you need to figure out where

[jade echo]

So i wouldn't be able to change it from the inspector

[jade echo]

Yeah

[latent sable]

First I would take a closer look at the scene with the hierarchy search function

second I would put Debug.Log in Awake on DCL and see where it's getting instantiated from, if it is

[tranquil juniper]

what does that even mean, is the gameobject hidden or what?

or are you presuming

[jade echo]

The scene has a settings object. The settings object updates a static class

[latent sable]

It might help if you shared some of this code with us

Especially DataCompanionListener

[jade echo]

Its all closed source otherwise I'd link you the repo lol

[latent sable]

It looks to me like DCL is just a pretty standard singleton

It's just assigning itself as Instance when it's created

so the thing to do is figure out where it's being created. 95% of the time, it's just placed in the scene from the editor at edit time

if not, then it has to be getting instantiated from somewhere - hence the Awake Debug.Log suggestion from earlier

or using the debugger

[latent sable]

Like - in the debugger right here, you can look at the stack and see what is Instantiating the object

[tranquil juniper]

yes sounds like a singleton to me
you can even use this to locate where an object is in a scene easier
https://docs.unity3d.com/6000.2/Documentation/ScriptReference/AssetDatabase.GetAssetOrScenePath.html

or debug log with a context arg

[latent sable]

Lots of tools at your disposal here - so let us know when you track it down

[jade echo]

Ok!!!

Thank you

[jade echo]

The callstack window seems to be empty and the threading window doesn't shine any more light on the invoker of dcl hmm

[tranquil juniper]

Because Awake is called by native engine code

thats why we told you how to figure out where this component is...

[jade echo]

Ok so i've made some progress

I now have a more concerete question

Ok so like I have bunch of scenes that operate the same way

that take settings data from another object

dcl is part of that

i have this one object Muse Listener

That reused in like 20 different scenes

I need to add back in the 6th element hree in the inspector

but like can i do it once instead of ahving to modify every single instance where this is used?

[tranquil juniper]

A prefab is the solution

then you just edit the prefab asset/apply changes to it

[jade echo]

so it looks like there is a prefab of this particular asset

But the muselist is empty

so then am i boned lmao

if the prefab isn't being used anyway

like i need to go back to make changes to every single scene

wait i misspoke

[tranquil juniper]

you would need to add an instance of the prefab to the scenes yes and then update references to the new object

sucks that whoever made this before did not think ahead 😐

[jade echo]

this has made me want to tear my hair out i swear to god

lmao

is it possible to make same change in multiple places?

somehow

i know that messing with the underlying yaml is probably no no

but could i?

[tranquil juniper]

you can automate it with some code. you can open scenes, modify the scene, set it as dirty, save and close the scene

[jade echo]

To close the loop on this, I ended up figuring it out

I just had to make the same change to modify the list in 26 different places

Nothing more complicated than that

but ughhhh

[latent sable]

While you did this I hope you switched everything to use a prefab

so when you need to change the list again you only need to do it in one place

[jade echo]

I didn't

But i should've

I needed to make a quick and dirty fix because my collaborator was waiting