Export tokens

[martinRenou]

Export tokens for other extensions to depend on them.

If tokens are not exported, one can retrieve them doing e.g.:

import { ILSPAdapterManager } from '@krassowski/jupyterlab-lsp/lib/tokens';

But this code will be compiled by webpack into

/* harmony import */ var _krassowski_jupyterlab_lsp_lib_tokens__WEBPACK_IMPORTED_MODULE_2__ = __webpack_require__(/*! @krassowski/jupyterlab-lsp/lib/tokens */ "./node_modules/@krassowski/jupyterlab-lsp/lib/tokens.js");

Meaning that the third-party extension now ships its own copy of @krassowski/jupyterlab-lsp, with its own definition of the Tokens.

If we export the tokens, third-party extensions are able to do:

import { ILSPAdapterManager } from '@krassowski/jupyterlab-lsp';

Which compiles to:

/* harmony import */ var _krassowski_jupyterlab_lsp__WEBPACK_IMPORTED_MODULE_2__ = __webpack_require__(/*! @krassowski/jupyterlab-lsp */ "webpack/sharing/consume/default/@krassowski/jupyterlab-lsp");

Meaning that all extensions which depend on those tokens will use the same tokens.

This is very important in JupyterLab 3 and the new federated modules, during the plugin activation, because JupyterLab relies on the Token instances themselves, not the name of the token.

Third-party extensions will be able to define jupyterlab-lsp as a shared packages (a package that is shared with other extensions) so it's not duplicated and bundled in all third-party extensions.

They can enable this by adding the following in their package.json:

"jupyterlab": {
    "extension": true,
    "outputDir": "my_extension/labextension",
    "sharedPackages": {
      "@krassowski/jupyterlab-lsp": {
        "bundled": false,
        "singleton": true
      }
    }
  }

https://github.com/jupyterlab/jupyterlab/blob/b29bfeb81e707dcb963d7d8e39a5d2ca1a036546/builder/metadata_schema.json#L28-L62

[bollwyvl]

Lgtm! Doesn't have to be on this PR, but how can we test this and keep it tested? There's an open issue for full fledged examples, but we could make a very small, unpublished extension that just spied on all the known tokens. Might even be useful for debugging/testing! From an integrity point of view: the token pattern is quite distinct and boiler-platey, so should be easy to find, and ensure it has been exported.

[krassowski]

Thank you. Probably the thing that caused me problems when I was trying to extend from outside....