Extract the Comm Python package

[martinRenou]

Currently working on a Python comm package on https://github.com/martinRenou/comm for now, but it should probably be moved in the IPython org
This PR relies on the new comm package https://github.com/ipython/comm

This has the benefit of being able to:

• remove the ipykernel dependency in ipywidgets Using the new Comm Python package jupyter-widgets/ipywidgets#3533
• remove the ipykernel monkey patch in xeus-python POC: Creation of a Comm Python package jupyter-xeus/xeus-python#548
• remove the ipykernel package mock in jupyterlite's pyolite
• remove the ipykernel package mock in emscripten-forge

[martinRenou]

I marked the PR as ready to review!

I might be wrong but the ipyparallel issue seems unrelated?

  =========================== short test summary info ============================
  ERROR  - DeprecationWarning: Jupyter is migrating its paths to use standard p...
  !!!!!!!!!!!!!!!!!!!! Interrupted: 1 error during collection !!!!!!!!!!!!!!!!!!!!
  =============================== 1 error in 0.90s ===============================

[blink1073]

I might be wrong but the ipyparallel issue seems unrelated?

Correct

[blink1073]

Thanks!

[blink1073]

I'll cut a minor release with this change early next week.

[ccordoba12]

@blink1073, is there full compatibility for projects that import the comm module from here? We do that in Spyder-kernels.

[blink1073]

Yes, the equivalent classes are exported from the comm module.

[maartenbreddels]

This broke compatibility in Solara, since I was doing

• https://github.com/widgetti/solara/blob/c41b87089164a4761ffc925a015a79072054ec0a/solara/server/kernel.py#L163

Giving me:

>       self.comm_manager = CommManager(parent=self, kernel=self)
E       TypeError: __init__() got an unexpected keyword argument 'parent'

Not sure if this should be considered a public API (the constructor), if so, happy to open an issue.

[maartenbreddels]

@martinRenou really nice to see this out this soon btw :) congrats

[blink1073]

I think the cause is the same as #1026