Dev install fails without Jupyter lab

[jdemeyer]

The relation between ipywidgets and jupyterlab is not so clear to me.

Is there a compelling reason why dev-install.sh requires Jupyterlab to be installed? I could easily change that script to skip the installation of jupyterlab_widgets if Jupyterlab is not installed. Would that be a good idea?

[SylvainCorlay]

I think that it is the right thing to do to have the dev installation to require jupyterlab since it is the future main target environment for widgets.

Regarding the dependency order

A ipywidgets is the kernel-side package
B1 widgetsnbextension is the notebook-server-side notebook extension package (which could be in a different environement than the kernel)
B2 jupyterlab_widgets is the notebook-server-side lab extension package (which could be in a different environement than the kernel)

The logical dependency direction is that ipywidgets should be installable without widgetsnbextension of jupyterlab_widgets, and reversely.

However, we kept the feature that ipywidgets should be usable as a standalone package for someone who installs everything (kernel and client) in the same environment.

[jdemeyer]

It's not a big issue, but I did find it surprising/confusing that ipywidgets itself does not require Jupyterlab, but the dev install does require Jupyterlab. Why not allow the option of doing the dev install without Jupyterlab for people who don't care about Jupyterlab?

[SylvainCorlay]

Why not allow the option of doing the dev install without Jupyterlab for people who don't care about Jupyterlab?

For now, we don't depend on jupyterlab. This is only the dev-install script. To be honest, I don't use this script personally.

[jasongrout]

I don't use the dev install script either. I did add the JLab stuff there to help someone else who was doing widgets in JLab. We could put the JLab stuff behind a switch if you want.

[hainm]

if developers do not use it personally, why bothering to keep it to avoid confusion? :D

[SylvainCorlay]

Some occasional contributors requested it :)

[hainm]

ha, fair enough. I just wish all the Jupyter-related projects (Python+JS) have the same way to install packages for contributors.

[jdemeyer]

We could put the JLab stuff behind a switch if you want.

See #1023.

[jasongrout]

Fixed in #1023.