bpo-29581: bpo-29581: Make ABCMeta.__new__ pass **kwargs to type.__new__ (GH-527) (GH-1282)
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, see
https://bugs.python.org/issue29581.
* added a test combining ABCMeta and __init_subclass__
* Added NEWS item
(cherry picked from commit bd583ef9857d99f9145ad0bb2c4424cc0baa63fc)
* [3.6] bpo-29581: Make ABCMeta.__new__ pass **kwargs to type.__new__ (GH-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, see
https://bugs.python.org/issue29581.
* added a test combining ABCMeta and __init_subclass__
* Added NEWS item.
(cherry picked from commit bd583ef9857d99f9145ad0bb2c4424cc0baa63fc)
* **kwargs -> ``kwargs`` in attempts to fix the Travis build.
* Quote the **kwargs
diff --git a/Lib/abc.py b/Lib/abc.py
index 1cbf96a..43a34a0 100644
--- a/Lib/abc.py
+++ b/Lib/abc.py
@@ -129,8 +129,8 @@
# external code.
_abc_invalidation_counter = 0
- def __new__(mcls, name, bases, namespace):
- cls = super().__new__(mcls, name, bases, namespace)
+ def __new__(mcls, name, bases, namespace, **kwargs):
+ cls = super().__new__(mcls, name, bases, namespace, **kwargs)
# Compute set of abstract method names
abstracts = {name
for name, value in namespace.items()
diff --git a/Lib/test/test_abc.py b/Lib/test/test_abc.py
index e1765f0..4bc8382 100644
--- a/Lib/test/test_abc.py
+++ b/Lib/test/test_abc.py
@@ -404,5 +404,17 @@
self.assertEqual(B.counter, 1)
+class TestABCWithInitSubclass(unittest.TestCase):
+ def test_works_with_init_subclass(self):
+ saved_kwargs = {}
+ class ReceivesClassKwargs:
+ def __init_subclass__(cls, **kwargs):
+ super().__init_subclass__()
+ saved_kwargs.update(kwargs)
+ class Receiver(ReceivesClassKwargs, abc.ABC, x=1, y=2, z=3):
+ pass
+ self.assertEqual(saved_kwargs, dict(x=1, y=2, z=3))
+
+
if __name__ == "__main__":
unittest.main()