F1 help mode in the REPL

[johnslavik]

Bug report

Bug description:

I've recently discovered F1 key bind to enter help mode in the REPL and found some problems:

1. Pressing F1 multiple times will "stack" help modes. If you press F1 3 times, you now have to exit 3 times.

2. Whatever the buffer is, help mode will write immediately past the buffer:

   

3. If you press F1 while tab-completing, help banner will glitch on top of the overlay and then the overlay will leak into help mode:

   

4. If you enter paste mode (F3), enter help mode (F1), leave paste mode (F3), leave help mode (exit), you get back to paste mode (expected prompt mode). This looks similar to a lock ordering deadlock.

   If you enter help mode with help and then enter and leave paste mode, this doesn't happen and we're correctly back at prompt mode.

   There might be more edge cases to this (prompt strings getting confused, etc.).

F1 is not a suggested feature anywhere in the REPL (unless you, well, type help and read about F1 there), so it is very likely that people don't know it exists. I only found that it was mentioned in https://docs.python.org/3/whatsnew/3.13.html#a-better-interactive-interpreter and https://peps.python.org/pep-0762/.

We could build guardrails that F1 isn't re-entrant and is pressed at the right moment (which could be challenging to do from the UX perspective because error reporting overlays are disabled by default at the runtime level), but I'm not sure if it is worth the complexity.

The F1 binding appears to provide limited user value (help exists already) while introducing many state-management edge cases. I think the easiest fix to all these issues is to remove the ability to press F1 entirely.

The welcome banner always suggested typing help for help (typing help is the same--resorts to _sitebuiltins._Helper()--except help> isn't colorized then).

Unless F1 is worth keeping?

CPython versions tested on:

CPython main branch

Operating systems tested on:

macOS

Linked PRs

• GH-148191: Toggle helper instead of nesting instances when using key bindings #121668

[MazinSharaf]

We could remove F1 completely, but maybe we should make seperate issues to fix one by one for this F1 help feature. I think that we should test the latter first before removing the F1 shortcut.

[MazinSharaf]

I'm gonna try fix the bugs one by one in a PR and see if it works, otherwise I'll just remove the F1 shortcut.

[johnslavik]

Thanks @MazinSharaf!

I think I'd wait for some feedback on this first (cc @ambv @pablogsal @lysnikolaou).

If we keep it, F1 should likely be a fully tracked mode (like the F2 history mode).

My main question is whether F1 is worth keeping, because maybe it's easier to maintain just one way to enter help mode. Note that none of these issues happen with the help command. A key bind complicates things because we have to track state (which we don't and for most cases this is fine, except those reported).

F1 is also fairly new, only 2 years old.

[MazinSharaf]

Alright, sounds good. If they suggest to keep F1 mode, I think we should split this into multiple issues so we can do one small bug fix at a time, and also just tidies things up.

Thank you @johnslavik !

P.S.
Fixing the F1 stacking problem where you have to quit multiple times if you spam F1.

[johnslavik]

P.S. Fixing the F1 stacking problem where you have to quit multiple times if you spam F1.

Ok, just keep in mind that this issue wasn't well discussed yet. There might be other issues where the path forward is clear, but in this case it's best to not submit any PRs just yet. Nevertheless, have fun spelunking! Thanks for contributing!

[devdanzin]

See also #121584.

[StanFromIreland]

See also #121584.

That's a duplicate, @johnslavik can you combine your findings with it and close please?

[johnslavik]

That's a duplicate, @johnslavik can you combine your findings with it and close please?

Not a pure duplicate--I've clarified what was and wasn't fixed, and I've noted that we track F1 separately here. I suggest we close both issues jointly. Thanks for catching this @devdanzin.