Error cell [14] issubclass() arg 1 must be a class

[DanD364]

Hello,

Thank you very much for this amazing work.
I am trying to understand a bit better differentiable physics for fluid dynamics and this would help me a lot.

However when I am trying to run your code there is an error on cell 14 that I was unable to solve. Maybe due to an update of HfArgumentParser? Everything ran well on the previous cells (except for a small typo on cell 5 where there were some spaces after the '%' sign but that's straight forward to fix)

Do you have an idea on how to fix it and run your code?

Thank you very much

[NickGeneva]

Hi @DanD364

This looks like a problem with the HfArgParser and some Python magic it uses. For Python 3.9 I have to hack around a solution to get it to function. By now its likely out of date for python 3.10, so maybe try downgrading to python 3.9?

[edwardsmith999]

Thank you for an interesting paper and making the package available.

I have a student trying to reproduce the cylinder results on Colab, but as it is now 3.10 by default it returns the above error.
To go to Python3.9 downgrading is needed. Trying the technique here:
https://stackoverflow.com/questions/68657341/how-can-i-update-google-colabs-python-version
3.8 replaced by 3.10 causes a

WARNING: The following packages were previously imported in this runtime:
      [cycler,kiwisolver]
     You must restart the runtime in order to use newly installed versions"

and a crash when "restart runtime" is clicked.

Given downgrading Python seems to be impossible, would it be possible to fix for later versions of Python?

[edwardsmith999]

Just created a pull request which seems to fix for Python 3.10