README.md Installation section possibly missing some context?

This is more of a question for clarification than a bug report or anything, but wanting to have a wee look at the library with a view to experimenting with a tool built around it, I was trying to get the examples up and running first (apologies if this isn’t the correct place to ask this; so please point me in the right direction if so). For context:

1. I was initially working with the css branch at @willmcgugan’s suggestion of the best place to look.
2. I’ve currently got zero experience with poetry (got sucked into pipenv some time back and… yeah, I know, I know) so I’m also finding my way with that too.

Having forked and cloned and switched to the css branch I did a poetry install and initially wondered if this:

Once installed you can run the following command for a quick test, or see examples (below):

python -m textual.app

was correct? This could be my ignorance showing but would it not be:

poetry run python -m textual.app

instead? Working on that assumption I run into the following:

Traceback (most recent call last):
  File "/Users/davep/develop/python/textual/src/textual/devtools/client.py", line 28, in <module>
    import msgpack
ModuleNotFoundError: No module named 'msgpack'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/local/Cellar/python@3.10/3.10.5/Frameworks/Python.framework/Versions/3.10/lib/python3.10/runpy.py", line 196, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "/usr/local/Cellar/python@3.10/3.10.5/Frameworks/Python.framework/Versions/3.10/lib/python3.10/runpy.py", line 86, in _run_code
    exec(code, run_globals)
  File "/Users/davep/develop/python/textual/src/textual/app.py", line 52, in <module>
    from .devtools.client import DevtoolsClient, DevtoolsConnectionError, DevtoolsLog
  File "/Users/davep/develop/python/textual/src/textual/devtools/client.py", line 31, in <module>
    raise DevtoolsDependenciesMissingError(
textual.devtools.client.DevtoolsDependenciesMissingError: Textual Devtools requires installation of the 'dev' extra dependencies.

That leaves me a bit stuck as, from what I can tell from the poetry docs, it will install all dependencies, including dev dependencies, by default, and the only related switch is the one that doesn’t install the dev dependencies.

Given the above, I thought I’d try the same in the main branch (with the modified command for running the demo app) and it works fine.

So… while very much keeping in mind Textual is a moving target at the moment, am I just being thrown off by the fact that the README is lagging in the css branch, and should the command to test textual.app be explicit about using poetry to run python to run the app?

[willmcgugan]

Great! I plan on rewriting that README before the CSS branch lands. Hopefully not much longer.

[willmcgugan]

Ah, you’ll need the dev extras.

Try this:

poetry install --extras dev

python -m textual.app won’t do anything in the CSS brach. fun stuff is in sandbox/will