Python 3.9 environments break when installing due to dataclasses dependency

[jishida0620]

Hi. When I tried to install chemoton following the guidance on the README, pip completely broke with an error that makes it impossible to use pip anymore.

Environment

• Python 3.9.16
• Ubuntu Linux
• pip 22.0.4

Steps to reproduce

python3.9 -m venv chemoton_env
source chemoton_env/bin/activate
git clone https://github.com/qcscine/chemoton.git
cd chemoton
pip install -r requirements-dev.txt

Error

After installation, any pip command fails with:

Traceback (most recent call last):
  File "/home/me/.py39/bin/pip", line 5, in <module>
    from pip._internal.cli.main import main
  ...
  File "/home/me/.py39/lib/python3.9/site-packages/dataclasses.py", line 550, in _is_classvar
    return type(a_type) is typing._ClassVar
AttributeError: module 'typing' has no attribute '_ClassVar'

Investigation

I found that the dependency chain chemoton → scine_art → svgutils → dataclasses causes this issue. The dataclasses package (0.6) is a Python 3.6 backport that shouldn't be installed on Python 3.7+, but somehow it gets installed and breaks the Python environment.

Questions

Does chemoton officially support Python 3.9? I couldn't find specific Python version requirements in the documentation.
Is there a known workaround for this installation issue?
Would it be possible to add constraints to prevent the dataclasses package from being installed on Python 3.7+?

I'm stuck and can't proceed with using chemoton. Any help would be greatly appreciated!
Thanks for developing this interesting project - I'm looking forward to exploring chemical reaction networks once I can get past this installation issue.

[weymutht]

So far, I didn't use Chemoton with Python 3.9, but I used it successfully with Python 3.10 and 3.11. Neither Chemoton nor scine_art place a version restriction on the svgutils or dataclasses package. You could try to manually add some restriction to requirements-dev.txt. Alternatively, you could manually install suitable versions of dataclasses and svgutils before executing pip install -r requirements-dev.txt.

[jishida0620]

Thank you for your reply. I found a similar issue, and the solution there fixed my problem.

rm -rf lib/dataclasses-0.6.dist-info

rm lib/dataclasses.py