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inspect: getmembers calls properties #82518Description
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GitHub fields:
assignee = None
closed_at = None
created_at = <Date 2019-10-01.12:01:59.088>
labels = ['type-bug', 'library', '3.9']
title = 'inspect: getmembers calls properties'
updated_at = <Date 2020-03-29.19:22:40.724>
user = 'https://github.com/jnsdrtlf' bugs.python.org fields:
activity = <Date 2020-03-29.19:22:40.724>
actor = 'jnsdrtlf'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2019-10-01.12:01:59.088>
creator = 'jnsdrtlf'
dependencies = []
files = []
hgrepos = []
issue_num = 38337
keywords = ['patch']
message_count = 9.0
messages = ['353688', '353698', '353871', '353872', '353895', '353900', '360715', '360748', '365274']
nosy_count = 3.0
nosy_names = ['cheryl.sabella', 'hongweipeng', 'jnsdrtlf']
pr_nums = ['16521']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue38337'
versions = ['Python 3.9'] Activityjnsdrtlf commented on Oct 1, 2019 MannequinAuthor More actions When calling inspect.getmembers on a class that has a property (@Property), the property will be called by the getattr call in getmembers.
Example:
import inspect
class Example:
def __init__(self, var):
self._var = var
print('__init__')
def foo(self, bar):
print(bar)
print('foo')
@property
def var(self):
print('Access property')
return self._var
if __name__ == '__main__':
ex = Example('Hello')
print('--- getmembers from instance ---')
print(inspect.getmembers(ex))
print('--- getmembers from class ---')
print(inspect.getmembers(Example))Result:
__init__
--- getmembers from instance ---
Access property
[('__class__', <attribute '__class__' of 'object' objects>), ..., ('var', 'Hello')]
--- getmembers from class ---
[('__class__', <attribute '__class__' of 'object' objects>), ..., ('var', <property object at 0x...>)]
Expected:
__init__
--- getmembers from instance ---
[('__class__', <attribute '__class__' of 'object' objects>), ..., ('var', <property object at 0x...>)]
--- getmembers from class ---
[('__class__', <attribute '__class__' of 'object' objects>), ..., ('var', <property object at 0x...>)] s-sanjay commented on Oct 1, 2019 the issue happens in 2.7 as well hongweipeng commented on Oct 3, 2019 The results of this example are different from mine(version 3.7.4).
__init__
--- getmembers from instance ---
Access property
[('__class__', <class '__main__.Example'>), ... ('var', 'Hello')]
--- getmembers from class ---
[('__class__', <class 'type'>),'var', <property object at 0x>)]
jnsdrtlf commented on Oct 3, 2019 MannequinAuthor More actions
The results of this example are different from mine(version 3.7.4)
I do not really see any difference. What do you mean? hongweipeng commented on Oct 4, 2019 I mean why member __class__ is expected to be <attribute '__class__'...>). I check PR16521,for class, it always gets <attribute '__class__'...>). jnsdrtlf commented on Oct 4, 2019 MannequinAuthor More actions Oh, yes I see what you mean. That's my fault, it seems like I copied the wrong line. Sorry.
But the important piece is the 'var' attribute. Sorry for the confusion. csabella commented on Jan 26, 2020 jnsdrtlf commented on Jan 27, 2020 MannequinAuthor More actions
Here is a link to the discussion of this on ideas
Thank you for posting the link.
I feel like I came to a dead end with this issue. As I am fairly new to CPython and have never contributed to this project before, I have no idea how to address this and to whom. Maybe this is just to irrelevant and not important, but even then we should probably close this issue or mark it as "indefinitely postponed" or something similar. jnsdrtlf commented on Mar 29, 2020 MannequinAuthor More actions I'm still thinking about this bug/issue/undefined behaviour. Today I wanted to test its behaviour with async:
import inspect
class Foo:
def __init__(self, bar):
self._bar = bar@property
async def spam(self):
print('Called spam')
return self._bar
if __name__ == '__main__':
instance = Foo('eggs')
members = inspect.getmembers(instance)This will result in a RuntimeWarning:
RuntimeWarning: coroutine 'Foo.spam' was never awaited
members = inspect.getmembers(instance)
RuntimeWarning: Enable tracemalloc to get the object allocation traceback
Sure, async properties might not be particularly beautiful or best-practice, but I frequently stumble upon code where getmembers would fail – just like this example. However, I am still clueless about what to do. interifter commented on May 30, 2025 Looks like this is still around with at least 3.12. Not a popular bug :)
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