virtual_documents customization

[fcollonval]

References

Fixes #353

Code changes

Move the ".virtual_documents" definition to a configuration in LanguageServerManager. Its default value is kept
but that default value can be overwritten by the environment variable JP_LSP_VIRTUAL_DIR

User-facing changes

None - except if they must know about the virtual document folder.

Backwards-incompatible changes

None

Chores

• linted
• tested
• documented
• changelog entry

[bollwyvl]

Good stuff!

It's unreliable to use os.path stuff for URIs because windows... pathlib.Path.as_uri() might be the better approach (we basically don't support py35 anymore), or fudge it and just use "/".join(), though then you have to worry about trailing slashes, etc.

The hard-coded string .virtual_documents may also appear in some other places as well, maybe the listener.

Anyhow, we would probably need a test of this being configured and (ab)used by the front end... e.g. spaces, non-ASCII, etc. Errors in this part of the (st|h)ack are extremely hard for end users to reason about, as the errors end up coming from the language servers talk about a folder that they might not even know about...

[fcollonval]

Thanks @bollwyvl for the review

After a second look on the code and to take into account your remarks, do you think the following is a good idea:

virtual_documents_uri =  normalized_uri(pathlib.Path(contents.root_dir) / manager.virtual_documents_dir)

[bollwyvl]

Yes, normalized_uri would do the thing!

[fcollonval]

Sorry for the useless small commits at the end.
Don't hesitate to squash & merge this one.

[krassowski]

Thank you!