ObservableList custom inspector Editor no longer reactive

[thestonefox]

Steps to reproduce

• Add a GameObjectObservableList
• Add a listener to the Added event
• Add a listener to the Removed event
• Populate the Elements collection with 1 GameObject

Run the scene

• Set the Elements collection size to 0
• Set the Elements collection size to 1
• Populate the element with a GameObject

Expected behavior

It should fire the Removed event when the collection size changes to 0 It should fire the Added event when the collection size changes to 1

Current behavior

No events are fired

[thestonefox]

Doing a git bisect shows a change in malimbe has caused the issue

https://github.com/ExtendRealityLtd/Malimbe/commit/e4cbe1093f40eccb4b7de86358e8f55e833daafe

merged into Zinnia at https://github.com/ExtendRealityLtd/Zinnia.Unity/commit/614f1bfa1066409283a79a3122aebb01d9cf5f0c

[thestonefox]

The line in Malimbe InspectorEditor.cs

if (changeCheckScope.changed
                        && Application.isPlaying
                        && (!(targetObject is Behaviour behaviour) || behaviour.isActiveAndEnabled)
                        && ChangeHandlerMethodInfos.Count > 0)

Removing && ChangeHandlerMethodInfos.Count > 0 fixes the issue.

I believe this was the only actual change in the Malimbe commit (everything else is just reversing the order of the check)

But I believe the Malimbe commit is specifically to add that offending check, so just removing it isn't the solution.

[thestonefox]

Ok so wrapping

ApplyModifiedProperty(property, ChangeHandlerMethodInfos.Count > 0);

like

else if (changeCheckScope.changed)
{
    BeforeChange(property);
    ApplyModifiedProperty(property, ChangeHandlerMethodInfos.Count > 0);
    AfterChange(property);
}

Seems to fix the issue.

From dumping out some info though, it seems that the ObsList when changed has a ChangeHandlerMethodInfos.Count of 0 which is why the main chunk of code doesn't actually run.

So I'm confused as to why the above does fix it as each of those methods simply does a foreach on the ChangeHandlerMethodInfos but as proved they are both 0 so wouldn't actually do anything anyway?

[thestonefox]

Could this actually be an issue in the Zinnia ObservableListEditor perhaps where it's not assigning change handlers so Malimbe generated code can't pick up on it?

[bddckr]

Could this actually be an issue in the Zinnia ObservableListEditor perhaps where it's not assigning change handlers so Malimbe generated code can't pick up on it?

The change handlers are looked up in the superclass, not in this Zinnia subclass of the editor. The subclass just overrides (and adds to) some of the superclass' methods. None of those is doing the actual handler lookup.

It could very well be the subclass, but probably not for the reason of change handler lookups.

[bddckr]

else if (changeCheckScope.changed)
{
    BeforeChange(property);
    ApplyModifiedProperty(property, ChangeHandlerMethodInfos.Count > 0);
    AfterChange(property);
}

Seems to fix the issue.

The subclass ObservableListEditor doesn't care about the ChangeHandlerMethodInfos, which is why it seems like this change doesn't actually change any logic.

It's the fact that the subclass' Before/AfterChange methods are called that is fixing it. I believe this is the fix we're looking for.

[thestonefox]

Fixed with https://github.com/ExtendRealityLtd/Zinnia.Unity/pull/403