Infer script extension based on Jupyter kernel - 'auto' extension

[z-m-k]

If I provide a list of let's say: "ipynb,jl,py" it would be great if jupytext inferred which script extensions to create based on the kernel specified in ipynb.

[mwouts]

Sure, we could do that. What would you think of using a keyword like script or auto for this (or any other that you would suggest)? That would allow to preserve the current functionality, which may be useful to people who mix multiple languages in a notebook.

[z-m-k]

Yes, auto would work best for this.

[mwouts]

I have implemented this on branch v0.8.0. Would you like to test it? You should be able to use 'auto' in all the options that accepts extensions. See for instance the tests: https://github.com/mwouts/jupytext/blob/v0.8.0/tests/test_contentsmanager.py#L440

[z-m-k]

auto works, but auto:percent ends up in :light formatting.

[z-m-k]

More precisely with notebook metadata:

  "jupytext": {
    "formats": "ipynb,auto:percent"
  }

The script metadata is as follows:

#   jupytext:
#     formats: ipynb,auto:percent,py:light

[mwouts]

Thanks @z-m-k for the feedback. I confirm that I also observe the same behavior. I'll soon add a few more tests, and correct this.