ExtensionApp: change extension_name to name.

[Zsailer]

Changes the extension_name trait to name in ExtensionApp.

This addresses issues in #222 and #224. @echarles

[echarles]

Thx @Zsailer. So for now this PR doesn't pick the python extension standard mecanism but we stick with the _jupyter_server_extension_paths?

I have pulled the changes and updated the example. I fail with

  File "/Users/echar4/datalayer/repos/jupyter-server/examples/simple/simple_ext1/application.py", line 48, in initialize_handlers
    (r'/{}/default'.format(self.extension_name), DefaultHandler),
AttributeError: 'SimpleApp1' object has no attribute 'extension_name'

[Zsailer]

That’s right, @echarles. I think the entry point discussion can be separated from this for now. We’ll discuss that at our next server meeting.

I’ll update the examples directory next

[echarles]

Cool! Having a way to create e.g. jupyter_lab_config,.py will be an excellent first step (PS: I won't be able to join today meeting)

[Zsailer]

I've updated the examples (sorry for the delay, here).

This should be ready for merge.

[echarles]

Thx Zach. There are still some extension_name used, at least here.

https://github.com/Zsailer/jupyter_server/blob/ff7826636e9a47665eb6a99ae1d28982441941e6/examples/simple/simple_ext1/application.py#L48-L53

BTW As discussed, I will open a PR to run the examples by GitHub Actions.

[echarles]

Works fine for me. Thx Zach for doing this.

[Zsailer]

Thanks, @echarles. Merging!

[echarles]

@Zsailer I have updated the jlab branches to latest master including this PR.

It works, but when I change name=jupyterlab to name=lab, I receive exeception

  File "/Users/echar4/datalayer/repos/jupyter-server/jupyter_server/serverapp.py", line 1534, in init_server_extensions
    mod, metadata_list = _get_server_extension_metadata(module_name)
  File "/Users/echar4/datalayer/repos/jupyter-server/jupyter_server/extension/serverextension.py", line 43, in _get_server_extension_metadata
    m = import_item(module)
  File "/opt/datalayer/opt/miniconda3/envs/datalayer/lib/python3.7/site-packages/traitlets/utils/importstring.py", line 43, in import_item
    return __import__(parts[0])
ModuleNotFoundError: No module named 'lab'

I have nailed down the issue but we need to discuss about that.

[echarles]

@Zsailer for example, if you change in the simple_ext1 the name and you say name = 'ext1', the server launches fine with jupyter server --ServerApp.jpserver_extensions="{'ext1': True}" but fails with python -m simple_ext1 or launched via the entrypoints.