Show status message when updating command line buffer

[Realiserad]

I have made a plugin which replaces the command line buffer using commandline --replace. It works, but if the plugin fails for some reason, it would be nice to show a status emoji somewhere (e.g. ❌) to indicate to the user that an error occurred.

Is there such a mechanism in fish?

[zanchey]

The right-side prompt might be the place to put it.

[Realiserad]

That's what I figured as well! However, I couldn't get it to put anything in the right-side prompt without rendering the prompt again (i.e. to press Enter on the keyboard). Did I miss anything? 🙂

[zanchey]

You might need to call commandline -f repaint to redraw the right prompt.

(In future, it might be worth including what you have tried already, to improve the quality of responses)

[Realiserad]

I made a uhum.. clumsy attempt. 😇

Created a .config/fish/conf.d/foo.fish which looks like this:

bind \n foo

function foo
  # Complicated business logic producing an error every time...
  # Put status emoji in the terminal
  eval (echo "function fish_right_prompt; echo '❌'; end")
  commandline --function repaint
  # Great it works! But how do I get rid of it when the user
  # presses *Enter*?
end

Restarted the terminal and pressed Ctrl+J to trigger the foo function. Unfortunately the ❌ sticks around after pressing e.g. Ctrl+C or Enter to get a new prompt. I tried to add functions --erase fish_right_prompt at the end of the foo function but then it doesn't display the ❌ at all.

[zanchey]

If you want to wipe it on those keys, you would need something like this:

function fish_right_prompt
   echo $mychar
end

function mybinding
   # Complicated business logic producing an error every time...
  set -g mychar ❌
  commandline --function repaint
end

bind \cj mybinding

function clearstatus
  set -e mychar
end

bind \r 'clearstatus; commandline -f execute'
bind \cc 'clearstatus; commandline -f cancel-commandline'

[Realiserad]

Thank you, @zanchey, I really appreciate the help!

Following your advice, I was able to get it to work (for reference, here is my commit).

There is only one small issue I cannot wrap my head around. The complicated business logic takes a while to execute, so it would be great to show a ⏳ when it's "thinking".

I tried to put a set -g mychar ⏳; commandline -f repaint in the beginning of the function, but it doesn't do anything. A one-minute digging into Rust suggest that repaint puts something on a queue and that the actual repaint happens at a later stage. Is there a way to repaint immediately?

[zanchey]

The documentation for commandline does spell this out - the arguments to --function are added to the queue, but it's not processed until the reader is ready to take more input.