fix: prevent dupe calls

[tlambert03]

trying to fix the duplicate call thing mentioned in #544 (review)

[tlambert03]

ugh... this is just a real annoying problem.

1. in order to truly support the proper Optional[type] return annotation that @Czaki was going for in Allow to use Optional annotation in function return type for magicgui functions napari/napari#5595, magicgui needs to move from a simple type -> list[callback] map, to a much more complicated set[type] -> list[callback] map... and then when looking up a callback for a return type annotation, look for the first set[type] that is a superset of the return callback set.
2. that more complicated map makes everything more complicated:
   • it slows down callback lookup at runtime
   • it makes it much harder to undo type registration (e.g. in the type_registered context manager)

basically, this all just further emphasizes that the return_callback feature of register_type is far more complicated to do "correctly", and makes me want to deprecate the whole feature altogether as mentioned in #543 ...

I really don't know the best solution here.

[tlambert03]

one possibility here is just to temporarily go back to the previous behavior (that I absolutely thing was incorrect behavior) of calling callbacks registered for Type even when the return annotation of the @magicgui function is Optional[Type] (as mentioned in #541).

That's a big bummer, cause it's just obviously wrong behavior. @Czaki, what do you think here?

[Czaki]

Why not just check presence of callback in lust before append? Registration type should be rare operation and such list should be short.

[tlambert03]

Because if we're dealing with sets as keys you now have to check all keys for a subset match, remember which ones matched, etc...

[tlambert03]

It's not that it's not possible, it's just getting uglier and uglier for something that was an accidental "feature/bug" to begin with

[Czaki]

Because of type2callback return first callback list where superset is found this test will fail:

def test_proper_call():
    @magicgui
    def func(a: int, b: int) -> int:
        return a + b

    mock1 = Mock()
    mock2 = Mock()

    register_type(int, return_callback=mock1)
    register_type(Optional[int], return_callback=mock2)

    func(1, 2)

    mock2.assert_called_once()
    mock1.assert_called_once()

[tlambert03]

closing, see #546