classy not working

[DinorahBarbosa]

Hello,

I was trying to use class on my new env, with python 3.9 and I wanted to use classy, but it doesn't work even when I install it with pip

(py39forge) dinorah@dinorah:~/class_ide$ python
Python 3.9.23 | packaged by conda-forge | (main, Jun  4 2025, 17:57:12) 
[GCC 13.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import classy
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: dynamic module does not define module export function (PyInit_classy)

I noticed that for the README in the python folder it says classy should be used with python2, so I made a new env with python 2.7.18, but then I can't install classy there either because it doesn't work with setup.py or with pip install classy. I'm not sure what to do.

Best regards,

Dinorah

[adriantee625]

Hi @DinorahBarbosa,

I tried to replicate your error but couldn't — it's unlikely to be related to the Python version, since classy works for me on both Python 3.9.22 and 3.12.8.

I'm not sure of your exact installation steps, but it's possible that previous installations of classy are still lingering in your environment. To ensure a clean setup, in your environment, you can remove them with

pip uninstall classy -y

Then to check whether it's fully removed, run:

python -c "import importlib.util; print(importlib.util.find_spec('classy'))"

It should return None. If not, repeat the uninstall until it does.

Once that's clean, assuming you've cloned the class_public repository from GitHub, the simplest way to install classy is to enter the class_public directory:

cd ~/class_public

and do

pip install .

Alternatively, you could also do make clean; make -j within the class_public directory.

Hope that helps! Feel free to follow up if you're still encountering issues.

Cheers,
Adrian