Repository navigation
[3.12] Behavior change: __getattr__ gets called after property raises NotImplementedError #103551
Description
Hi,
Version: 3.12.0a7
OS: Windows
While testing pytest in 3.12 on Windows, we noticed an odd behavior that we believe might be a bug/regression.
Consider this minimal example:
class Stat:
@property
def owner(self):
print("--> accessing owner")
raise NotImplementedError("owner not implemented")
def __getattr__(self, item):
return getattr(1, "foobar")
s = Stat()
s.owner(Using getattr(1, ...) there just to have an object in-place; in the real code 1 is actually another object, but the outcome is the same).
Running this in Python 3.11.2 (and previous versions), we get this output:
λ py -3.11 --version
Python 3.11.2
λ py -3.11 .tmp\reproducer.py
--> accessing owner
Traceback (most recent call last):
File "e:\projects\pytest\.tmp\reproducer.py", line 12, in <module>
s.owner
File "e:\projects\pytest\.tmp\reproducer.py", line 5, in owner
raise NotImplementedError("owner not implemented")
NotImplementedError: owner not implemented
NotImplementedError is raised from the property access, and __getattr__ is never called.
In Python 3.12.0a7 however we get:
λ py -3.12 --version
Python 3.12.0a7
λ py -3.12 .tmp\reproducer.py
--> accessing owner
Traceback (most recent call last):
File "e:\projects\pytest\.tmp\reproducer.py", line 12, in <module>
s.owner
File "e:\projects\pytest\.tmp\reproducer.py", line 8, in __getattr__
return getattr(1, "foobar")
^^^^^^^^^^^^^^^^^^^^
AttributeError: 'int' object has no attribute 'foobar'
The property is still being accessed (as shown by the print call), but NotImplementedError is being swallowed/ignored, and __getattr__ seems to be getting called as a fallback.
Changing the example slightly:
class Stat:
@property
def owner(self):
print("--> accessing owner")
raise NotImplementedError("owner not implemented")
def __getattr__(self, item):
raise AttributeError("foobar")
s = Stat()
s.ownerIn Python 3.11 the behavior stays the same as before, however in Python 3.12 we now get:
λ py -3.12 .tmp\reproducer.py
--> accessing owner
Traceback (most recent call last):
File "e:\projects\pytest\.tmp\reproducer.py", line 5, in owner
raise NotImplementedError("owner not implemented")
NotImplementedError: owner not implemented
The above exception was the direct cause of the following exception:
Traceback (most recent call last):
File "e:\projects\pytest\.tmp\reproducer.py", line 12, in <module>
s.owner
File "e:\projects\pytest\.tmp\reproducer.py", line 8, in __getattr__
raise AttributeError("foobar")
^^^^^^^^^^^^^^^^^^^^^^^^
SystemError: <class 'AttributeError'> returned a result with an exception set
Please let us know if you need more information.
Activity
AlexWaygood commentedon Apr 14, 2023
This may have already been fixed by #103332; it looks quite similar to the regression test that was added in #103336
sobolevn commentedon Apr 15, 2023
Hi, @nicoddemus 👋
Please, try the latest
main. It should be fixed now. If so, please feel free to close this issue :)nicoddemus commentedon Apr 15, 2023
Thanks!
Indeed I tried on the latest main (2b6f5c3) and it now works the same as Python 3.11.
Closing the issue then, thanks!
AlexWaygood commentedon Apr 15, 2023
Great, thanks for confirming!
add test case for pythongh-103551