https://github.com/python/cpython/commit/cfdf376e2a35878d48a1ad811e1664e92d6d30f1 commit: cfdf376e2a35878d48a1ad811e1664e92d6d30f1 branch: 3.13 author: Miss Islington (bot) <[email protected]> committer: sobolevn <[email protected]> date: 2024-09-01T18:19:56+03:00 summary:
[3.13] gh-91126: Docs and tests for slotted dataclasses with `__init_subclass__` (GH-123342) (#123568) gh-91126: Docs and tests for slotted dataclasses with `__init_subclass__` (GH-123342) (cherry picked from commit 75e72822a390df81ca11355d8e0aac88e4046c27) Co-authored-by: sobolevn <[email protected]> files: M Doc/library/dataclasses.rst M Lib/test/test_dataclasses/__init__.py diff --git a/Doc/library/dataclasses.rst b/Doc/library/dataclasses.rst index fcb5e8bad295a0..db1e6af530bdeb 100644 --- a/Doc/library/dataclasses.rst +++ b/Doc/library/dataclasses.rst @@ -185,10 +185,21 @@ Module contents - *slots*: If true (the default is ``False``), :attr:`~object.__slots__` attribute will be generated and new class will be returned instead of the original one. If :attr:`!__slots__` is already defined in the class, then :exc:`TypeError` - is raised. Calling no-arg :func:`super` in dataclasses using ``slots=True`` will result in - the following exception being raised: - ``TypeError: super(type, obj): obj must be an instance or subtype of type``. - The two-arg :func:`super` is a valid workaround. See :gh:`90562` for full details. + is raised. + + .. warning:: + Calling no-arg :func:`super` in dataclasses using ``slots=True`` + will result in the following exception being raised: + ``TypeError: super(type, obj): obj must be an instance or subtype of type``. + The two-arg :func:`super` is a valid workaround. + See :gh:`90562` for full details. + + .. warning:: + Passing parameters to a base class :meth:`~object.__init_subclass__` + when using ``slots=True`` will result in a :exc:`TypeError`. + Either use ``__init_subclass__`` with no parameters + or use default values as a workaround. + See :gh:`91126` for full details. .. versionadded:: 3.10 diff --git a/Lib/test/test_dataclasses/__init__.py b/Lib/test/test_dataclasses/__init__.py index ffb8bbe75c504f..260e0d74917181 100644 --- a/Lib/test/test_dataclasses/__init__.py +++ b/Lib/test/test_dataclasses/__init__.py @@ -3664,6 +3664,38 @@ class A(WithDictSlot): ... self.assertEqual(A().__dict__, {}) A() + @support.cpython_only + def test_slots_with_wrong_init_subclass(self): + # TODO: This test is for a kinda-buggy behavior. + # Ideally, it should be fixed and `__init_subclass__` + # should be fully supported in the future versions. + # See https://github.com/python/cpython/issues/91126 + class WrongSuper: + def __init_subclass__(cls, arg): + pass + + with self.assertRaisesRegex( + TypeError, + "missing 1 required positional argument: 'arg'", + ): + @dataclass(slots=True) + class WithWrongSuper(WrongSuper, arg=1): + pass + + class CorrectSuper: + args = [] + def __init_subclass__(cls, arg="default"): + cls.args.append(arg) + + @dataclass(slots=True) + class WithCorrectSuper(CorrectSuper): + pass + + # __init_subclass__ is called twice: once for `WithCorrectSuper` + # and once for `WithCorrectSuper__slots__` new class + # that we create internally. + self.assertEqual(CorrectSuper.args, ["default", "default"]) + class TestDescriptors(unittest.TestCase): def test_set_name(self): _______________________________________________ Python-checkins mailing list -- [email protected] To unsubscribe send an email to [email protected] https://mail.python.org/mailman3/lists/python-checkins.python.org/ Member address: [email protected]
