Feature request: allow launching editor when viewing stdin

[khollbach]

Pressing v gives me an editor with the current file and line number. I love this feature, and I'd like to be able to launch an editor this way even when I'm paging through stdin.

My use-case is syntax-highlighting via piping the output of another command to less -R. This works great, but I lose ability to edit the file with v. I can almost fix this by setting the filename in an environment variable and customizing LESSEDIT="%E ?lm+%lm. ?f%f:$less_stdin_filename.". This doesn't quite work, because less stops short of invoking the editor, with the message Cannot edit standard input (press RETURN), which is reasonable enough.

A possible solution could be to introduce a commandline flag --launch-editor-stdin (or --stdin-allow-editor or something) that turns off this error message. A bit clunky maybe, but if this is a patch you'd accept, I'd be happy to work on it.

[gwsw]

I don't quite understand your LESSEDIT setting -- what is $less_stdin_name?

In any case, perhaps using a new command for this would work better, as discussed here:
#66

[khollbach]

Sorry for the late reply. The solution you linked almost does what I want, except that would give me a new buffer with the file's contents; I would rather be editing the file itself so that my changes are saved.

I didn't explain my example all that well. Here's the exact use-case, where bat is basically cat with syntax-highlighting. The LESSEDIT says "if %f (current file name) exists, use that; otherwise use the environment variable less_stdin_filename".

LESSEDIT='%E ?lm+%lm. ?f%f:$less_stdin_filename.'

# E.g.: view filename.c
function view {
    less_stdin_filename="$1"
    bat "$@" | less -R
}

I would use this to view a file, and pressing v would let me edit the file. It almost works, but as I mentioned, the "Cannot edit standard input" error message is displayed before my LESSEDIT string is evaluated. Adding a commandline flag to always evaluate LESSEDIT is the only thing I could think of, but maybe there's another way to get the behaviour I want.

[gwsw]

Ok, I see what you're trying to do now. I think using LESSOPEN to preprocess the file would be a better approach. Something like

function view {
    LESSOPEN='|bat %s' less -R "$1"
}

This should allow you to use the v command to edit the original file.

[khollbach]

Perfect! This does exactly what I want, I just had to add --color=always to bat. Thank you for your help :)

One minor question: is there a way to suppress the WARNING: This file was viewed via LESSOPEN (press RETURN) prompt that appears before opening the editor?

[gwsw]

The message cannot be suppressed. It's a warning that what you see in the editor may not match what you were viewing in less, because of the LESSOPEN processing.

[khollbach]

Ok, no worries; thanks again for the help!