Shift Handler?.UpdateValue to happen after all PropertyChanged events have fired

[PureWeen]

Currently our Handler?.UpdateValue call fires during the top call here from BindableObject

This means that sometimes the Handler will have a premature vision of the world. The Handler update should fire after as many of the PropertyChanged events have settled as possible.

For example it leads to issues like this

#5586

The Parent on the FormattedText is set inside the BP.OnPropertyChanged which fires after the Handler?.UpdateValue fires. So anything the BP.OnPropertyChanged changes will now have to re-propagate.

[antonfirsov]

@PureWeen should we consider bringing other events which fire in OnPropertyChanged after property.PropertyChanged or are we fine with a minimal solution that pushes Handler?.UpdateValue after all the other events?

Is this issue mostly about validation whether such a minimal change breaks something?

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PS: Actually, firing Handler?.UpdateValue outside of OnPropertyChanged may lead to side-effects, since derived custom properties are also calling into OnPropertyChanged and may expect Handler?.UpdateValue to execute as an effect. Should we just exchange the order of property.PropertyChanged and OnPropertyChanged ?

[ghost]

We've moved this issue to the Backlog milestone. This means that it is not going to be worked on for the coming release. We will reassess the backlog following the current release and consider this item at that time. To learn more about our issue management process and to have better expectation regarding different types of issues you can read our Triage Process.

[PureWeen]

Related
#22347

I think we could clean up 22347 once we conceive of how we want this to work.

We should probably move the handler update code to fire about here

maui/src/Controls/src/Core/BindableObject.cs

Line 645 in 28e9cbb

}

The difficulty comes with maintaining behavior when users manually call OnPropertyChanged