Python autocomplete in console lacks parity with jupyter/ipython

[astrowonk]

iPython (and thus Jupyter) support the ability to expose custom autocomplete information in class definitions. Here is a silly one:

class DemoAutocomplete:

    """demo class"""

    def __getitem__(self, item):
        return item + item

    @staticmethod
    def _ipython_key_completions_():
        """required for custom autocompletion of subscriptables"""
        return list(range(10))

In iPython or Jupyter, autocomplete now works for the subscriptable instance of this class.

However in Positron console, the autocomplete suggestions are both irrelevant (appears to be every defined object) and don't include the key completions data:

It would be wonderful if we could have autocomplete parity with juptyer/ipython. I use custom classes for autocomplete extensively as we have many tables and other data structures whose names I can't remember, so I create helper subscriptable objects with defined _ipython_key_completions_ that allow me to access this data easily.

[sharon-wang]

Thanks for this feedback @astrowonk!

I don't think I see an existing issue for this under python completions, but this gap in experience seems similar to:

• Python: no completions provided for csv.reader() #2753
• No column suggestion in pandas methods #5436

---

@seeM does this sound similar to any existing issue you're aware of? If not, I'll convert this over!

[seeM]

This is a new feature request to support the _ipython_key_completions_ completions hook. It is something we're aware of. It doesn't work currently because we don't use IPython's completions system, we go directly to a language server which can inspect the kernel's variables.

We'd probably implement this by patching Jedi as we've done before, or we could try to get it added in the Jedi repo. Here's the upstream Jedi issue that was tracking this but was closed at some point: davidhalter/jedi#771

[astrowonk]

The iPython docs claim that it will also look at __dir__ for autocompletion suggestions, but the code for _get_keys does not appear to do anything with __dir__.

__dir__ does not seem to help the Positron console either (so I guess Jedi also doesn't look at __dir__).

I was hoping I could just also define __dir__ and Jedi/Positron would autocomplete my example but no such luck!

[sharon-wang]

Thank you both!

I've copied this over to an issue so we can better track it along with other python completions items: #8451.

Feel free to upvote 👍 the issue to express interest and comment on the issue with additional thoughts!

[astrowonk]

It may be of interest, but the Marimo team has a very similar open issue they are actively working on. (Marimo currently doesn't autocomplete pandas sub-scriptable column names - in addition to the _ipython_key_completion_)

Sorry I meant to post this on #8451 !

[sharon-wang]

No worries! I've copied your message over. I'll close out this discussion in favour of #8451!