Issue 25830: _TypeAlias: Discrepancy between docstring and behavior (original) (raw)

Issue25830

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This issue has been migrated to GitHub: https://github.com/python/cpython/issues/70017

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process

Created on 2015-12-09 11:57 by flying sheep, last changed 2022-04-11 14:58 by admin. This issue is now closed.

Messages (4)
msg256154 - (view)	Author: (flying sheep) *	Date: 2015-12-09 11:57
_TypeAlias claims in its docstring that “It can be used in instance and subclass checks”, yet promptly contradicts itself if you try it: “Type aliases cannot be used with isinstance().” it would be useful to either document (and therefore bless) type_impl, or make it actually work with isinstance (probably by delegating to type_impl)
msg258776 - (view)	Author: Berker Peksag (berker.peksag) *	Date: 2016-01-21 22:36
Looks like the docstring is a bit misleading. ``isinstance(m, Match)`` behavior is already tested in the test suite: https://hg.python.org/cpython/file/default/Lib/test/test_typing.py#l1297
msg258778 - (view)	Author: Guido van Rossum (gvanrossum) *	Date: 2016-01-21 23:25
Actually isinstance() shouldn't be supported by most things in typing.py (except for those that mimic existing collection ABCs). Even issubclass() should be taken out according to the BDFL-delegate for PEP 484. See https://github.com/ambv/typehinting/issues/136
msg277560 - (view)	Author: Guido van Rossum (gvanrossum) *	Date: 2016-09-27 22:26
Fixed by 09cc43df4509.