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bpo-41905: added abc.update_abstractmethods #22485

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Merged
gvanrossum merged 21 commits into from
Oct 6, 2020
Merged

bpo-41905: added abc.update_abstractmethods #22485

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f65b0f8
added update_abstractmethods
Oct 1, 2020
c04ba74
📜🤖 Added by blurb_it.
blurb-it[bot] Oct 1, 2020
ea69ae6
fix whitespaces
Oct 1, 2020
8b76715
Merge branch 'master' of https://github.com/bentheiii/cpython into ma…
Oct 1, 2020
61c4f40
documentation fixes
Oct 1, 2020
a5a9fd7
additional tests
Oct 1, 2020
5e1fffc
rename test
Oct 1, 2020
2f95b84
added explicit check for ABCMeta
Oct 1, 2020
3986c98
optimization on total_ordering
Oct 2, 2020
4f3d846
update_abstractmethods now ignores non-abstract classes
Oct 3, 2020
74473c8
total_ordering now only overrides abtract methods defined in supercla…
Oct 3, 2020
92326c9
doc fix
Oct 3, 2020
1e47ee4
excluded total_ordering from this issue
Oct 3, 2020
740183f
documented ABC being ABC unaware
Oct 3, 2020
114028e
fixed potential bug with deletion of implementation
Oct 4, 2020
ba8df08
added layered test case
Oct 4, 2020
29dba37
update_abstractmethods doesn't care about subclasses for now
Oct 4, 2020
779e6cf
doc fixes
Oct 4, 2020
eea97f4
Update Doc/library/abc.rst
bentheiii Oct 5, 2020
8eec6c2
Update Lib/abc.py
bentheiii Oct 5, 2020
5698153
Update Lib/abc.py
bentheiii Oct 5, 2020
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added explicit check for ABCMeta
  • Loading branch information
ben avrahami committed Oct 1, 2020
commit 2f95b840e24e1f2e358035633f5aa156d15e2ee6
2 changes: 2 additions & 0 deletions Doc/library/abc.rst
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Expand Up @@ -345,6 +345,8 @@ The :mod:`abc` module also provides the following functions:

If *cls* has any subclasses, raises a :exc:`RuntimeError`.

If *cls* is not an instance of ABCMeta, raises a :exc:`TypeError`.

.. versionadded:: 3.10

.. rubric:: Footnotes
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20 changes: 15 additions & 5 deletions Lib/abc.py
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Expand Up @@ -127,7 +127,7 @@ def update_abstractmethods(cls):

If a class has had one of its abstract methods implemented after the
class was created, the method will not be considered implemented until
this function is called. Alternativly, if a new abstract method has been
this function is called. Alternatively, if a new abstract method has been
added to the class, it will only be considered an abstract method of the
class after this function is called.

Expand All @@ -137,17 +137,27 @@ class after this function is called.
Returns cls, to allow usage as a class decorator.

If cls is has any subclasses, raises a RuntimeError.

If cls is not an instance of ABCMeta, raises a TypeError.
"""
if not hasattr(cls, '__abstractmethods__'):
# We check for __abstractmethods__ here because cls might by a C
# implementation or a python implementation (especially during
# testing), and we want to handle both cases.
raise TypeError('cls must be an abstract class or subclass of an abstract'
' class')
if cls.__subclasses__():
raise RuntimeError("cannot update abstract methods of class after subclassing")
raise RuntimeError("cannot update abstract methods of class after"
" subclassing")

abstracts = set()
# check the existing abstract methods, keep only the ones that are
# still abstract
# Check the existing abstract methods, keep only the ones that are
# still abstract.
for name in cls.__abstractmethods__:
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@iritkatriel iritkatriel Oct 1, 2020 •
edited
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Since you didn't check in this function that it's an ABC, it's not guaranteed that cls.__abstractmethods__ works:

>>> class FooABC: pass
... 
>>> FooABC.__abstractmethods__
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: __abstractmethods__

Maybe add a test for when this function is called for a non-ABC.

value = getattr(cls, name, None)
if getattr(value, "__isabstractmethod__", False):
abstracts.add(name)
# also add any other newly added abstract methods
# Also add any other newly added abstract methods.
for name, value in cls.__dict__.items():
if getattr(value, "__isabstractmethod__", False):
abstracts.add(name)
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11 changes: 11 additions & 0 deletions Lib/test/test_abc.py
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Expand Up @@ -558,6 +558,17 @@ class B(A):
B()
self.assertEqual(B.__abstractmethods__, set())

def test_update_non_abc(self):
class A:
pass

@abc.abstractmethod
def updated_foo(self):
pass

A.foo = updated_foo
self.assertRaises(TypeError, abc.update_abstractmethods, A)


class TestABCWithInitSubclass(unittest.TestCase):
def test_works_with_init_subclass(self):
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