Enable using federated extensions in dev mode when a flag is set.

[jasongrout]

References

Fixes #9235

Code changes

User-facing changes

This is a much easier way to develop extensions against a development install of JupyterLab than the current add:sibling approach. While it may not work all the time, I think it will be helpful sufficiently often that we should make it possible.

Backwards-incompatible changes

[jupyterlab-dev-mode]

Thanks for making a pull request to JupyterLab!

To try out this branch on binder, follow this link:

[jtpio]

Does that mean linking core packages with yarn as mentioned in #9235 (comment) is not necessary?

Or the federated extension should be built using the dev version of lab to properly populate the shared packages.

[jasongrout]

Does that mean linking core packages with yarn as mentioned in #9235 (comment) is not necessary?

It depends. If no linking is done, the federated extensions will be built against existing package versions, but will use the dev versions at runtime. If the APIs change, that would be a problem. To fully test, you would indeed need to do some sort of linking so that typescript could do its compile-time checking properly.

[blink1073]

Thanks!

[jasongrout]

I added some help text warning that federated extensions may not work in a dev install if they were compiled against published packages.