Description

assignee = None
closed_at = None
created_at = <Date 2019-10-03.13:28:44.060>
labels = ['3.8', 'type-bug', 'library', '3.9', '3.10']
title = "inspect.iscoroutinefunction / isgeneratorfunction / isasyncgenfunction can't handle  partialmethod objects"
updated_at = <Date 2022-03-05.22:48:08.143>
user = 'https://github.com/mjpieters'

activity = <Date 2022-03-05.22:48:08.143>
actor = 'jalaziz'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2019-10-03.13:28:44.060>
creator = 'mjpieters'
dependencies = []
files = []
hgrepos = []
issue_num = 38364
keywords = ['patch']
message_count = 2.0
messages = ['353849', '414598']
nosy_count = 5.0
nosy_names = ['mjpieters', 'asvetlov', 'yselivanov', 'dreamsorcerer', 'jalaziz']
pr_nums = ['16600']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue38364'
versions = ['Python 3.8', 'Python 3.9', 'Python 3.10']

Activity

1. mjpieters commented on Oct 3, 2019

   

   mjpietersmannequin

   on Oct 3, 2019

   MannequinAuthor

   More actions

   This is a follow-up to bpo-33261, which added general support for detecting generator / coroutine / async generator functions wrapped in partials. It appears that partialmethod objects were missed out.

   While a partialmethod object will produce a functools.partial() object on binding to an instance, the .func attribute of that partial is a bound method, not a function, and the current _has_code_flag implementation unwraps methods *before* it unwraps partials.

   Next, binding to a class produces a partialmethod._make_unbound_method.._method wrapper function. _unwrap_partial can't unwrap this, as it doesn't handle this case; it could look for the _partialmethod attribute and follow that to find the .func attribute.

   Test case:

   import inspect
   import functools
   
   class Foo:
       async def bar(self, a): return a
       ham = partialmethod(bar, "spam")
   
   print(inspect.iscoroutinefunction(Foo.bar)  # True
   print(inspect.iscoroutinefunction(Foo.ham)  # False
   instance = Foo()
   print(inspect.iscoroutinefunction(instance.bar)  # True
   print(inspect.iscoroutinefunction(instance.ham)  # False

   Reacted by Jan Lukány
2. mjpieters

   added

   3.8 (EOL)end of lifeend of life

   stdlibStandard Library Python modules in the Lib/ directoryStandard Library Python modules in the Lib/ directory

   type-bugAn unexpected behavior, bug, or errorAn unexpected behavior, bug, or error

   on Oct 3, 2019
3. jalaziz commented on Mar 5, 2022

   

   jalazizmannequin

   on Mar 5, 2022

   Mannequin

   More actions

   I've recently ran into this via unittest.mock.patch.object. Mocking an asynchronous partial method returns MagicMock and not AsyncMagicMock, causing some pretty hard to debug failures.
4. jalaziz

   added

   3.9 (EOL)end of lifeend of life

   3.10 (EOL)end of lifeend of life

   on Mar 5, 2022
5. ezio-melotti

   transferred this issue fromon Apr 10, 2022
6. graingert commented on Jul 16, 2022

   

   graingert

   on Jul 16, 2022

   Contributor

   More actions

   see also #67707
7. pavelm10 commented on Dec 1, 2022

   

   pavelm10

   on Dec 1, 2022

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   The above test case slightly changed:

   def test_dummy():
       import inspect
       import functools
   
       class Foo:
           async def bar(self, a): return a
           ham = functools.partialmethod(bar, "spam")
   
       assert inspect.iscoroutinefunction(Foo.bar)  # True
       assert not inspect.iscoroutinefunction(Foo.ham)  # False
       instance = Foo()
       assert inspect.iscoroutinefunction(instance.bar)  # True
       assert inspect.iscoroutinefunction(instance.ham)  # False

   IS NOT failing for Python 3.10.7
   IS failing for Python 3.10.2
   Other 3.10.x not tested.
8. mjpieters commented on Dec 30, 2022

   

   mjpieters

   on Dec 30, 2022

   ContributorAuthor

   More actions

   The above test case slightly changed:

       assert inspect.iscoroutinefunction(Foo.bar)  # True
       assert not inspect.iscoroutinefunction(Foo.ham)  # False

   Why did you change the test to add not?
9. serhiy-storchaka

   added this to Inspect issues 🔍on Mar 5, 2024

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