Here's some more context. I have an interactive CLI application built using
zsh, and am already using alternate screen to draw contents in it. vared's
default behavior (of clearing current line of cursor and below) makes sense
when a script calling vared does not use alternate screen. This is because
screen contents on and below the current cursor position (after vared is
called) in an interactive shell are mostly not exciting (generally empty).
But the same is not true for applications that use alternate screen and
paint entire screen with text. Let's say the application designer wants to
use the first line on screen to get user input. They might not want any
other line on screen to get cleared or moved when vared is called. But that
doesn't seem possible with vared, as vared clears from current line the
cursor is on to everything below. IMO, vared makes an assumption that is
limiting (something that ``bash -e -p`` doesn't). It would be nice to have
a switch that disables vared's clearing behavior, and leaves it on
developer to insert commands to clear line/s. Till such a switch exists, is
it possible to zle and bypass such clearing?

Here's an example that shows vared always clears lines on and below the
cursor position on the screen.

```
tput smcup; tput clear; tput cup 0 0
for ((i=1;i<LINES;i=i+1)); do
    printf '%s\n' "$i. Hello world"
done
printf "\e[31m$i. Hello World\e[0m"
tput cup $((RANDOM%LINES)) 0
sleep 1
vared -f vared-finish -c -p "%{$(tput cup 0 0)%}Enter input: " userinput
tput rmcup
echo "User entered: $userinput"
```

P.S. I posted this to zsh-workers with an imagining that this likely will
turn into a feature request or bug report.


On Fri, Dec 30, 2022 at 9:56 AM Bart Schaefer <schaefer@brasslantern.com>
wrote:

> (Leaving this on -workers because of the possible bug mentioned at the
> end.)
>
> On Thu, Dec 29, 2022 at 9:38 PM OG Code Poet <ogcodepoet@gmail.com> wrote:
> >
> > Using Bash ``tput cup 0 0; read -e -p "Enter input: " userinput`` works
> well for getting a line of user input:
> >
> > * It does not clear screen below the prompt
> > * It allows user to use arrow keys to go to middle of line and edit a
> mistake they might have made while typing
>
> Bash is invoking the GNU "readline" library for the "read" builtin.
> Unlike ZLE, which despite having "line" in its name attempts to be a
> reasonable multi-line editor, readline is designed to do exactly what
> its name says, so it doesn't do any other screen prep.
>
> > How can this be achieved in zsh?
>
> Closest I can come up with is this:
>
> vared-finish() { tput rc }
> zle -N vared-finish
> tput sc
> vared -f vared-finish -c -p "%{$(tput cup 0 0)%}Enter input: " userinput
>
> However, this is not entirely satisfactory because the finish widget
> is not invoked if this is interrupted by ^C or ^G (send-break), and
> vared then clears the screen before exiting.  This is possibly a bug?
> Shouldn't the finish widget(s) always be run when the line editor
> exits, even if it exits "abnormally"?  (This affects the PS1 ZLE as
> well.)
>