bpo-29581: Make ABCMeta.new pass **kwargs to type.new (#527) · python/cpython@bd583ef (original) (raw)
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bpo-29581: Make ABCMeta.__new__ pass **kwargs to type.__new__ (#527)
Many metaclasses in the standard library don't play nice with __init_subclass__. This bug makes ABCMeta in particular with __init_subclass__, which is an 80/20 solution for me personally. AFAICT, a general solution to this problem requires updating all metaclasses in the standard library to make sure they pass **kwargs to type.__new__, whereas this PR only fixes ABCMeta. For context, seehttps://bugs.python.org/issue29581. * added a test combining ABCMeta and __init_subclass__ * Added NEWS item
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3 files changed
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -129,8 +129,8 @@ class ABCMeta(type): | ||
| 129 | 129 | # external code. |
| 130 | 130 | _abc_invalidation_counter = 0 |
| 131 | 131 | |
| 132 | -def __new__(mcls, name, bases, namespace): | |
| 133 | -cls = super().__new__(mcls, name, bases, namespace) | |
| 132 | +def __new__(mcls, name, bases, namespace, **kwargs): | |
| 133 | +cls = super().__new__(mcls, name, bases, namespace, **kwargs) | |
| 134 | 134 | # Compute set of abstract method names |
| 135 | 135 | abstracts = {name |
| 136 | 136 | for name, value in namespace.items() |
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -404,5 +404,17 @@ class C(A, B): | ||
| 404 | 404 | self.assertEqual(B.counter, 1) |
| 405 | 405 | |
| 406 | 406 | |
| 407 | +class TestABCWithInitSubclass(unittest.TestCase): | |
| 408 | +def test_works_with_init_subclass(self): | |
| 409 | +saved_kwargs = {} | |
| 410 | +class ReceivesClassKwargs: | |
| 411 | +def __init_subclass__(cls, **kwargs): | |
| 412 | +super().__init_subclass__() | |
| 413 | +saved_kwargs.update(kwargs) | |
| 414 | +class Receiver(ReceivesClassKwargs, abc.ABC, x=1, y=2, z=3): | |
| 415 | +pass | |
| 416 | +self.assertEqual(saved_kwargs, dict(x=1, y=2, z=3)) | |
| 417 | + | |
| 418 | + | |
| 407 | 419 | if __name__ == "__main__": |
| 408 | 420 | unittest.main() |
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -761,6 +761,9 @@ Library | ||
| 761 | 761 | - Issue #24142: Reading a corrupt config file left configparser in an |
| 762 | 762 | invalid state. Original patch by Florian Höch. |
| 763 | 763 | |
| 764 | +- Issue #29581: ABCMeta.__new__ now accepts **kwargs, allowing abstract base | |
| 765 | + classes to use keyword parameters in __init_subclass__. Patch by Nate Soares. | |
| 766 | + | |
| 764 | 767 | Windows |
| 765 | 768 | ------- |
| 766 | 769 |