Handle type guards properly in Receiver.filter()
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src/frequenz/channels/_receiver.py
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| # We need to use Any here because otherwise _Filter would have to deal with two | ||
| # different signatures. We can create two filter classes, one for regular functions | ||
| # and one for type guards, but then there is no way to tell at runtime which | ||
| # function is a type guard and which isn't to instantiate the correct class. | ||
| # Using Any here has no impact though, as thanks to the overloads, only the | ||
| # overloaded types will be accepted. | ||
| def filter( | ||
| self, filter_function: Callable[[ReceiverMessageT_co], Any], / | ||
| ) -> Receiver[Any]: |
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You don't need to change _Filter because TypeGuard is just another name for bool, with some additional semantic meaning. The type system knows assigning a TypeGuard value to a bool is fine.
| # We need to use Any here because otherwise _Filter would have to deal with two | |
| # different signatures. We can create two filter classes, one for regular functions | |
| # and one for type guards, but then there is no way to tell at runtime which | |
| # function is a type guard and which isn't to instantiate the correct class. | |
| # Using Any here has no impact though, as thanks to the overloads, only the | |
| # overloaded types will be accepted. | |
| def filter( | |
| self, filter_function: Callable[[ReceiverMessageT_co], Any], / | |
| ) -> Receiver[Any]: | |
| def filter( | |
| self, | |
| filter_function: ( | |
| Callable[[ReceiverMessageT_co], bool] | |
| | Callable[[ReceiverMessageT_co], TypeGuard[FilteredMessageT_co]] | |
| ), | |
| /, | |
| ) -> Receiver[ReceiverMessageT_co] | Receiver[FilteredMessageT_co]: |
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Interesting, I think what I tried was: filter_function: Callable[[ReceiverMessageT_co], bool | TypeGuard[FilteredMessageT_co]] and that didn't work.
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Updated. |
tests/test_broadcast.py
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| assert message == 8 | ||
| match message: | ||
| case int(): | ||
| assert message == 8 |
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Why is it necessary to have this check twice? (in line 267 and 270 ? assert message == 8 )
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I guess it could just be a pass inside the case, true. I just needed to put something :D
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I just changed the test to make sure the case int() is executed. mypy should verify this too thannks to the assert_never, but just in case.
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Thanks! Now it is clear for me why it was necessary :)
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Updated again. |
Now the `Receiver` type returned by `Receiver.filter()` will have the narrowed type when a `TypeGuard` is used. Signed-off-by: Leandro Lucarella <[email protected]>
Now the
Receivertype returned byReceiver.filter()will have the narrowed type when aTypeGuardis used.