Widgetslabextension package

Sorry in advance if an issue was already opened for this.

After a long discussion with @maartenbreddels yesterday we agreed that installing an interactive widgets library for JupyterLab is too complicated for users, and very error-prone. We think it might scare people off and result in giving up trying to use our extensions.

One of the issues we discussed was that when doing:

conda install ipyleaflet

jupyter labextension install jupyter-leaflet

You might get a Python package that is incompatible with the JS package, resulting in the Widget model not found error in JupyterLab.

@maartenbreddels @mariobuikhuizen and I think @vidartf went around this specific issue in their extensions by putting a tgz of the JS package under share/jupyter/lab/extensions, allowing JupyterLab to find the package and rebuild itself (either from the GUI or doing jupyter lab build).

This ensures having a version of the JS package compatible with the Python package. One would argue it makes the Python package dependent on the JS package, and I would agree it’s not a good thing, but usability would be improved.

I would like to propose doing the same thing in ipywidgets, with a new widgetslabextension package (widgetsnbextension counterpart) which installs the tgz at the right place. The only thing I am not sure about is how this package would be installed. Should it be a JupyterLab dependency? An ipywidgets dependency? Should the user install it manually?

I can come up with a PR myself if nobody is against it.

[jasongrout]

Actually, I do like jupyter_widgets, in that the “ipy” is specific to the python kernel, but the jupyter_widgets package is only for frontends, and is agnostic about the kernel language, etc.

[ianhi]

I don’t think I fully grasp the nuance of the dependency resolution problems but given:

One mismatch here is that the right frontend things to be installed depends on the frontend, not on the kernel-side ipywidgets

is there any possibility of jupyterlab-manager being included in jupyterlab itself? This seems like it would automatically would keep the frontend versions in sync.

Big 👍 to anything the removes the need to run jupyter labextension install @jupyter-widgets/jupyterlab-manager as this can be very confusing. For example here are some quotes from a colleague I was helping to get interactive plot working today:

why don’t i get an error message then?

your mystifying incantation works

why does jupyter notebook support this out of the box? and not jupyterlab

i might need to be the Luddite who sticks with notebooks

Related to the first quote is there any way to raise an error in python when the widget versions don’t match or jupyterlab-manager is not present? The failure state of mismatched javascript version or equivalent can be very opaque especially if someone doesn’t know about the webdev console.