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This repository was archived by the owner on Sep 3, 2026. It is now read-only.
[attribute-error] when usage is protected by an if statement #1867
Description
I have this class method:
@classmethod
def _adjust_instance_using_tzinfo(cls, instance: datetime) -> datetime:
if cls._mock_tzinfo:
offset = cls._mock_tzinfo.utcoffset(instance)
if offset is None:
raise TypeError('tzinfo with .utcoffset() returning None is not supported')
instance = instance - offset
return instance...where pytype complains but mypy does not, and it feels like the pytype complaint is erroneous:
[10/35] check testfixtures.datetime
FAILED: /Users/chris/vcs/git/testfixtures/.pytype/pyi/testfixtures/datetime.pyi
/Users/chris/virtualenvs/testfixtures_312/bin/python -m pytype.main --disable import-error --imports_info /Users/chris/vcs/git/testfixtures/.pytype/imports/testfixtures.datetime.imports --module-name testfixtures.datetime --platform darwin -V 3.12 -o /Users/chris/vcs/git/testfixtures/.pytype/pyi/testfixtures/datetime.pyi --analyze-annotated --nofail --quick /Users/chris/vcs/git/testfixtures/testfixtures/datetime.py
/Users/chris/vcs/git/testfixtures/testfixtures/datetime.py:264:22: error: in _adjust_instance_using_tzinfo: No attribute 'utcoffset' on None [attribute-error]
In Optional[datetime.tzinfo]
offset = cls._mock_tzinfo.utcoffset(instance)
~~~~~~~~~~~~~~~~~~~~~~~~~~
Even if I change the guarding if block to be if cls._mock_tzinfo is not None, the complaint remains.
Reacted by Harmon
Activity
martindemello commentedon Feb 11, 2025
pytype doesn't assume an attribute access returns the same object when called twice in succession. the workaround is to assign it to a local variable first, i.e.
x = cls.mock_tzinfo; if x: ...cjw296 commentedon Feb 12, 2025
@martindemello - hmm, that seems quite an unfortunate choice, do you know if there are plans to change that?
(the fact you refer to it as a workaround gives me a little hope...)
h-joo commentedon Aug 20, 2025
Hi, thank you for your report. Google is shifting its effort to a different approach for type checking apart from pytype, and we're not planning to put in any effort in the near future in pytype, so we'll close this issue. Please see the announcement here.
[Units] Suppress irrelevant attribute-error(s) from pytype
[Units] Suppress irrelevant attribute-error(s) from pytype
[Units] Suppress irrelevant attribute-error from pytype