[issue34498] Python 3.7 breaks on singledispatch_function.register(pseudo_type), which Python 3.6 accepted

Irit Katriel added the comment: Reproduced on 3.11. I've changed type because crash typically refers to segfault rather than an exception being raised. -- nosy: +iritkatriel type: crash -> behavior versions: +Python 3.10, Python 3.11, Python 3.9 -Python 3.7

[issue34498] Python 3.7 breaks on singledispatch_function.register(pseudo_type), which Python 3.6 accepted

Michael Selik added the comment: +1 for this use case. Until it's resolved, perhaps there should be a note in the singledispatch docs that types from the ``typing`` module should not be used? -- nosy: +selik ___ Python tracker

[issue34498] Python 3.7 breaks on singledispatch_function.register(pseudo_type), which Python 3.6 accepted

Change by Guido van Rossum : -- nosy: -gvanrossum ___ Python tracker ___ ___ Python-bugs-list mailing list Unsubscribe:

[issue34498] Python 3.7 breaks on singledispatch_function.register(pseudo_type), which Python 3.6 accepted

Sam Bishop added the comment: Would the enhancements to resolve this, by making singledispatch accept more things, also resolve the AssertionError from functools.singledispatch when passing it custom types, or should I raise this as a separate issue?

[issue34498] Python 3.7 breaks on singledispatch_function.register(pseudo_type), which Python 3.6 accepted

Ivan Levkivskyi added the comment: > Could we revert abstract types in `typing` to respond True to > `isinstance(..., type)` again? No, making them classes will cause significant performance penalty (I don't remember numbers now, but importing `typing` may be twice slower). Plus this will

[issue34498] Python 3.7 breaks on singledispatch_function.register(pseudo_type), which Python 3.6 accepted

Łukasz Langa added the comment: > I would say we could update the check in `functools` to accept more things. Could we revert abstract types in `typing` to respond True to `isinstance(..., type)` again? I don't want singledispatch, or any other library like it, to have to special-case

[issue34498] Python 3.7 breaks on singledispatch_function.register(pseudo_type), which Python 3.6 accepted

Change by Brett Cannon : -- nosy: +lukasz.langa ___ Python tracker ___ ___ Python-bugs-list mailing list Unsubscribe:

[issue34498] Python 3.7 breaks on singledispatch_function.register(pseudo_type), which Python 3.6 accepted

Ivan Levkivskyi added the comment: This is why we have 4 months of betas :-) On one hand making objects in `typing` module not classes was intentional, but on another hand this use case looks totally fine. I would say we could update the check in `functools` to accept more things. I am

[issue34498] Python 3.7 breaks on singledispatch_function.register(pseudo_type), which Python 3.6 accepted

Change by Serhiy Storchaka : -- nosy: +gvanrossum, levkivskyi ___ Python tracker ___ ___ Python-bugs-list mailing list Unsubscribe:

[issue34498] Python 3.7 breaks on singledispatch_function.register(pseudo_type), which Python 3.6 accepted

Michał Radwański added the comment: The change is not only in the added `isinstance` check: ~ $ python3.6 -q >>> import typing >>> isinstance(typing.Sequence, type) True >>> ~ $ python3.7 -q >>> import typing >>> isinstance(typing.Sequence, type) False >>> -- nosy: +enedil

[issue34498] Python 3.7 breaks on singledispatch_function.register(pseudo_type), which Python 3.6 accepted

New submission from Dutcho : In Python 3.6, the argument to the register() method of a single-dispatch function (i.e. a function decorated by @functools.singledispatch) can be a 'type-like' class (pseudo-type?) from e.g. the typing module that supports isinstance(). The below demonstrates