[3.13] gh-91126: Docs and tests for slotted dataclasses with `__init_… · python/cpython@cfdf376 (original) (raw)
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -185,10 +185,21 @@ Module contents | ||
| 185 | 185 | - *slots*: If true (the default is ``False``), :attr:`~object.__slots__` attribute |
| 186 | 186 | will be generated and new class will be returned instead of the original one. |
| 187 | 187 | If :attr:`!__slots__` is already defined in the class, then :exc:`TypeError` |
| 188 | - is raised. Calling no-arg :func:`super` in dataclasses using ``slots=True`` will result in | |
| 189 | - the following exception being raised: | |
| 190 | - ``TypeError: super(type, obj): obj must be an instance or subtype of type``. | |
| 191 | - The two-arg :func:`super` is a valid workaround. See :gh:`90562` for full details. | |
| 188 | + is raised. | |
| 189 | + | |
| 190 | + .. warning:: | |
| 191 | + Calling no-arg :func:`super` in dataclasses using ``slots=True`` | |
| 192 | + will result in the following exception being raised: | |
| 193 | + ``TypeError: super(type, obj): obj must be an instance or subtype of type``. | |
| 194 | + The two-arg :func:`super` is a valid workaround. | |
| 195 | + See :gh:`90562` for full details. | |
| 196 | + | |
| 197 | + .. warning:: | |
| 198 | + Passing parameters to a base class :meth:`~object.__init_subclass__` | |
| 199 | + when using ``slots=True`` will result in a :exc:`TypeError`. | |
| 200 | + Either use ``__init_subclass__`` with no parameters | |
| 201 | + or use default values as a workaround. | |
| 202 | + See :gh:`91126` for full details. | |
| 192 | 203 | |
| 193 | 204 | .. versionadded:: 3.10 |
| 194 | 205 |
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -3664,6 +3664,38 @@ class A(WithDictSlot): ... | ||
| 3664 | 3664 | self.assertEqual(A().__dict__, {}) |
| 3665 | 3665 | A() |
| 3666 | 3666 | |
| 3667 | +@support.cpython_only | |
| 3668 | +def test_slots_with_wrong_init_subclass(self): | |
| 3669 | +# TODO: This test is for a kinda-buggy behavior. | |
| 3670 | +# Ideally, it should be fixed and `__init_subclass__` | |
| 3671 | +# should be fully supported in the future versions. | |
| 3672 | +# See https://github.com/python/cpython/issues/91126 | |
| 3673 | +class WrongSuper: | |
| 3674 | +def __init_subclass__(cls, arg): | |
| 3675 | +pass | |
| 3676 | + | |
| 3677 | +with self.assertRaisesRegex( | |
| 3678 | +TypeError, | |
| 3679 | +"missing 1 required positional argument: 'arg'", | |
| 3680 | + ): | |
| 3681 | +@dataclass(slots=True) | |
| 3682 | +class WithWrongSuper(WrongSuper, arg=1): | |
| 3683 | +pass | |
| 3684 | + | |
| 3685 | +class CorrectSuper: | |
| 3686 | +args = [] | |
| 3687 | +def __init_subclass__(cls, arg="default"): | |
| 3688 | +cls.args.append(arg) | |
| 3689 | + | |
| 3690 | +@dataclass(slots=True) | |
| 3691 | +class WithCorrectSuper(CorrectSuper): | |
| 3692 | +pass | |
| 3693 | + | |
| 3694 | +# __init_subclass__ is called twice: once for `WithCorrectSuper` | |
| 3695 | +# and once for `WithCorrectSuper__slots__` new class | |
| 3696 | +# that we create internally. | |
| 3697 | +self.assertEqual(CorrectSuper.args, ["default", "default"]) | |
| 3698 | + | |
| 3667 | 3699 | |
| 3668 | 3700 | class TestDescriptors(unittest.TestCase): |
| 3669 | 3701 | def test_set_name(self): |