cattrs
cattrs copied to clipboard
python-attrs
ModuleNotFoundError: No module named 'exceptiongroup' (with poetry and python 3.10.1+)
Environment
- cattrs version: 22.1.0
- Python version: 3.10.5
- Operating System: Ubuntu 22.04
Description
When using poetry, the dependency spec for cattrs 22.1.0 doesn't install exceptiongroup for python versions >=3.10.1, <3.11.
It seems that pip interprets the constraint python = "<= 3.10" as roughly equivalent to python = "< 3.11", whereas poetry interprets it (perhaps more correctly?) as python = "<= 3.10.0", so doesn't behave correctly for patch versions greater than 0. In other words, on python 3.10.1, poetry's dependency resolver thinks exceptiongroup doesn't need to be installed.
Looks like this was already fixed in main. No need to rush the next minor release (22.2.0) if it's not ready, but a patch release for this (22.1.1) would be helpful.
What I Did
Start with python 3.10.1+ installed, and a minimal pyproject.toml:
[tool.poetry]
name = "cattrs-test"
version = "0.1.0"
description = ""
authors = []
[tool.poetry.dependencies]
python = ">=3.10.1,<3.11"
cattrs = "22.1.0"
[build-system]
requires = ["poetry-core>=1.0.0"]
build-backend = "poetry.core.masonry.api"
Then run from the command line:
pip install poetry # If not already installed
poetry install
python -c "import cattrs"
Traceback:
Traceback (most recent call last):
File "<string>", line 1, in <module>
File "/home/user/.virtualenvs/cattrs-test/lib/python3.10/site-packages/cattrs/__init__.py", line 1, in <module>
from cattr import converters, disambiguators, dispatch, errors, gen, preconf
File "/home/user/.virtualenvs/cattrs-test/lib/python3.10/site-packages/cattr/__init__.py", line 1, in <module>
from .converters import Converter, GenConverter, UnstructureStrategy
File "/home/user/.virtualenvs/cattrs-test/lib/python3.10/site-packages/cattr/converters.py", line 1, in <module>
from cattrs.converters import Converter, GenConverter, UnstructureStrategy
File "/home/user/.virtualenvs/cattrs-test/lib/python3.10/site-packages/cattrs/converters.py", line 12, in <module>
from cattrs.errors import IterableValidationError, StructureHandlerNotFoundError
File "/home/user/.virtualenvs/cattrs-test/lib/python3.10/site-packages/cattrs/errors.py", line 3, in <module>
from cattrs._compat import ExceptionGroup
File "/home/user/.virtualenvs/cattrs-test/lib/python3.10/site-packages/cattrs/_compat.py", line 38, in <module>
from exceptiongroup import ExceptionGroup
ModuleNotFoundError: No module named 'exceptiongroup'
Attached is an example poetry.lock showing that exceptiongroup wasn't picked up by the dependency resolver.
Workaround
This can be worked around by adding an explicit dependency on exceptiongroup, so I wouldn't consider this a super serious bug, but it would be helpful to have a PyPI release that fixes this for other users of cattrs + poetry + python 3.10.
Oh interesting, we've seen this at my job too but figured it was some sort of Poetry weirdness.
What's the exact fix though? Make it < 3.11?
That's right, the change you already made here: https://github.com/python-attrs/cattrs/blob/b1a681a60d07623618dfe440ac9c3ee6b9780307/pyproject.toml#L27
Works correctly for both pip and poetry.