Feature Request Request for VisualElement OnDestroy or OnRemoved event

Hi,

I think that it would be a good thing to add a OnDestroy or OnRemoed event on the VisualElement class.
Here is the reason why.

Imagine you have a simple integerField field with a UndoRecord:

Code (CSharp):

1. var integerField = new IntegerField("test Int");
2. integerField.isDelayed = true;
3. integerField.value = exampleObject.testInt;
4. integerField.RegisterValueChangedCallback(c => {
5.                
6.    Undo.RecordObject(exampleObject, exampleObject.name);
7.    exampleObject.testInt = c.newValue;
8.                
9. });

If possible I would like to add a undoRedoCallBack that updates the value:

Code (CSharp):

1. Undo.undoRedoPerformed += () => {
2.    integerField.value = exampleObject.testInt;
3. };

But what if the integerField is an element in a list where you can add and remove elements. I don't want the undoredoCallback to update an intergerField that is no longer displayed.
So it would be great if I could do something around the lines of:

Code (CSharp):

1. Undo.UndoRedoCallback updateValue = () => {
2.   integerField.value = exampleObject.testInt;
3. };
4. Undo.undoRedoPerformed += updateValue;
5. integerField.onRemove += () => { Undo.undoRedoPerformed -= updateValue; };

Please do let me know if I am overcomplicating things and if there is a simpler solution to make a correctly functioning undoredo value field without binding (I can't use binding because I am using abstract/generic classes and therefore its too complicated to get the object propertyPath of each property, I prefer setting the values manually)

Thank you for your time

 

Does this help?
https://forum.unity.com/threads/event-call-when-a-visualelement-is-removed.701102/#post-4781339

 

Thank you!
This works great:

Code (CSharp):

1.  integerField.RegisterCallback<DetachFromPanelEvent>(c => { Undo.undoRedoPerformed -= updateValue; });

I guess I should have read the UIElements Event documentation more attentively:
https://docs.unity3d.com/2019.1/Documentation/Manual/UIE-Events-Reference.html