Add remapping extensions for core

[PureWeen]

Description of Change

This PR adds a set of extension methods that we can use to ReMap mapper delegates inside core. This models the remapping mechanisms that we've already added to controls. Various scenarios come up where we just want to inject some additional logic into a subclassed handler but we still want the code from the base handler to run. This also ensures that if the user has replaced logic at the ViewHandler level, it will continue to run.

TODO

• Extension methods need better naming, but I didn't want to lose the end result of API discussions.

Issues Fixed

#17665

[ghost]

Hi @PureWeen. We have added the "s/pr-needs-author-input" label to this issue, which indicates that we have an open question/action for you before we can take further action. This PRwill be closed automatically in 14 days if we do not hear back from you by then - please feel free to re-open it if you come back to this PR after that time.

[mattleibow]

I think this is much better - and I am 60% sure that changing the return type is both breaking but not really.

[mattleibow]

I wonder if this is breaking... I think methods can't be overloaded just by return type, so this may actually work. I'll test and report back.

[mattleibow]

There is an alternative that we could do and not have more extension methods:

public static IPropertyMapper Mapper = new()
{
    [nameof(Xxx)] = MapXxx,
}
.Remap(mapper =>
{
    mapper.ModifyMapping(xxx, yyy);
    mapper.ReplaceMapping(xxx, yyy);
});

[ghost]

Hi @PureWeen.
It seems you haven't touched this PR for the last two weeks. To avoid accumulating old PRs, we're marking it as stale. As a result, it will be closed if no further activity occurs within 4 days of this comment. You can learn more about our Issue Management Policies here.

[hartez]

Chill out, robot - we're thinking.

[spadapet]

I have this open PR:

• ScrollView content needs layout when ScrollView.InvalidateMeasure is called #17639

My PR might be blocked on this draft PR. But if mine is completed first, I'll comment here that its fix needs to be adjusted.