Re: [PATCH] prompt: support generic non-visible regions

[Roman Perepelitsa <roman.perepelitsa@gmail.com>]

On Thu, Aug 11, 2022 at 4:37 PM Roman Perepelitsa
<roman.perepelitsa@gmail.com> wrote:
>
> I like this patch [...]

I should've said that I like the idea behind it. The patch implements
one part of it. To complete the implementation percent expansion needs
to output \001 and \002.

> No real-world use cases come to mind [...]

Here's one. If this is implemented, it'll be possible to compute the
width of prompt in columns with ${(m)#${(%%)PS1}} (perform prompt
expansion and then ask for width). This is necessary in prompts that
look like this:

    left------------------------right
    bottom%

The first line spans the whole width of the terminal. One example of
such prompt is `prompt bart` from `promptinit`. This particular prompt
can compute the width of `left` and `righ` by utilizing the knowledge
of their content. If these pieces could be specified by the end-user,
the problem would be more difficult. I've described one (rather
cumbersome) solution here:
https://www.reddit.com/r/zsh/comments/cgbm24/multiline_prompt_the_missing_ingredient/.

Roman.