Widgets 7.x release plan for JupyterLab 2.0

[jasongrout]

My current thinking is that we:

1. Release major versions of the js packages to support JLab 2.0. This involves a major upgrade to jupyterlab services, etc., as merged into the 7.x branch already. I've released several RC versions of the js packages, and tested upgrading custom widgets, and things seem to work well.
2. Release a patch release of widgetsnbextension, since it contains fixes for the font awesome upgrade in the notebook Change fontawesome support to work for fontawesome 4 and 5. #2793

[vidartf]

I think this code needs to change to import from phosphor?

ipywidgets/packages/base/src/registry.ts

Lines 4 to 6 in 47db2a9

	import {
	Token
	} from '@lumino/coreutils';

[vidartf]

(possibly also in master for 8.0?)

[jasongrout]

I think this code needs to change to import from phosphor?

Yes, good catch. I'm not sure how that made it into the 7.x branch. Do you want to make a PR?

(We should test the 7.x RC out there now to make sure it works on jlab 1) - it will probably fail from this, so we should test after cutting another RC with this change.

(possibly also in master for 8.0?)

I'm thinking that 8.0 will effect the switch to Lumino. Custom widget authors and users I think will understand that pythreejs is a major upgrade to switch to ipywidgets 8, and that way ipywidgets 8 will support JLab 2 and JLab 3 (but not JLab 1).

So the story to users/developers is:

• ipywidgets 7 fully supports jlab 1 and jlab 2. Custom widgets will need a patch release to add support for jlab 2 (just like they did for jlab 1)
• ipywidgets 8 supports jlab 2 (but not jlab 1). Custom widgets will need a major release to support ipywidgets 8
• Both ipywidgets 7 and 8 support classic notebook

[jasongrout]

Yes, good catch. I'm not sure how that made it into the 7.x branch. Do you want to make a PR?

Looks like it came in in a30e7dd. Not sure how I missed that. So we need to revert the phosphor->Lumino change basically everywhere.

[jasongrout]

Wait, never mind. The whole point here is that we have a major release of the base package and the jupyterlab manager, which is only for jlab 2. All those changes were intentional to get the widget manager to work in jlab 2. Custom widgets will be able to support jlab 1 and 2, though.

So to be clear:

• ipywidgets 7 supports jlab 1 (@jupyter-widgets/jupyterlab-manager@1), jlab 2 (@jupyter-widgets/jupyterlab-manager@2), and classic notebook (widgetsnbextension). Custom widgets will need a patch release to add support for jlab 2 (just like they did for jlab 1) by adding a new dependency version for the base package (^1 || ^2 || ^3)
• ipywidgets 8 supports jlab 2 (through another major release of @jupyter-widgets/jupyterlab-manager) and classic notebook (another major version of widgetsnbextension)

[vidartf]

Custom widgets will need a patch release to add support for jlab 2 (just like they did for jlab 1) by adding a new dependency version for the base package (^1 || ^2 || ^3)

So currently, the Token gets defined in @jupyterlab/base, and this is the one that causes the TypeScript compile error if lumino/phosphor gets mixed.

[vidartf]

To clarify, strongly typed plugin code fails to compile:

const plugin: IPlugin<Application<Widget>, void> = {
  id: 'myplugin',
  requires: [IJupyterWidgetRegistry],
  activate: () => {},
  autoStart: true
};

export default plugin;

Weakly typed plugins succeed:

module.exports = {
  id: 'myplugin',
  requires: [IJupyterWidgetRegistry],
  activate: () => {},
  autoStart: true
};

Examples in the wild for both types:

• https://github.com/vidartf/ipydatetime/blob/ca21fdf78a8ce5e3794f330e948c2f511b4876ae/ts/src/plugin.ts#L29-L36
• https://github.com/bloomberg/bqplot/blob/a5d3774700ec18a7718df04f26337677d96d7252/js/src/jupyterlab-plugin.ts#L24-L35

[jasongrout]

There may need to be some as any typecasts in plugins wanting to support both jlab 1 and jlab 2, I think.

[vidartf]

Sure. As long as we can offer that as an out for those that need to support both, that sounds ok. Most of my extensions are stable enough at this point, that I'll probably just release a new version tied to newest widgets, and newest lab only.

[jasongrout]

I released final versions of the npm packages to enable JupyterLab 2.0 support for ipywidgets.

For JupyterLab 2.0, to install ipywidgets, simply do jupyter labextension install @jupyter-widgets/jupyterlab-manager, just like usual.

For custom widget authors, I anticipate that all you need to do to add support for JupyterLab 2.0 is to publish a patch release of your npm package where you've updated your @jupyter-widgets/base dependency version requirement to include || ^3 (i.e., if you followed the instructions at https://ipywidgets.readthedocs.io/en/stable/changelog.html#updates-for-widget-maintainers, your dependency could look like:

"dependencies": {
  "@jupyter-widgets/base": "^1 || ^2 || ^3"
}

[jasongrout]

Closing as resolved at this point.