Re: Getting psql to redisplay command after \e

ne 3. 11. 2019 v 20:58 odesílatel Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr>
napsal:

>
> Hello Tom,
>
> >> I was suggesting something much simpler than rethinking readline
> handling.
> >> Does not mean that it is a good idea, but while testing the patch I
> would
> >> have liked the unfinished line to be in the current editing buffer,
> >> basically as if I had not typed <nl>.
> >
> > I did experiment with trying to do that, but I couldn't get it to work,
> > even with the single version of libreadline I had at hand. It appears
> > to me that readline() starts by clearing the internal buffer. Even if
> > we could persuade it to work in a particular readline version, I think
> > the odds of making it portable across all the libreadline and libedit
> > versions that are out there aren't very good. And there's definitely no
> > chance of being remotely compatible with that behavior when using the
> > bare tty drivers (psql -n).
>
> Argh, too bad.
>
> This suggests that readline cannot be used to edit simply a known string?
> :-( "rl_insert_text" looked promising, although probably not portable, and
> I tried to make it work without much success anyway. Maybe I'll try to
> investigate more deeply later.
>

pspg uses rl_insert_text

https://github.com/okbob/pspg/blob/59d115cd55926ab1886fc0dedbbc6ce0577b0cb3/src/pspg.c#L2522

Pavel

> Note that replacing the current buffer is exactly what history does. So
> maybe that could be exploited by appending the edited line into history
> (add_history) and tell readline to move there (could not find how to do
> that automatically, though)? Or some other history handling…
>
> > In practice, if you decide that you don't like what you're looking at,
> > you're probably going to go back into the editor to fix it, ie issue
> > another \e. So I'm not sure that it's worth such pushups to get the
> > data into readline's buffer.
>
> For me \e should mean edit, not edit-and-execute, so I should be back to
> prompt, which is the crux of my unease with how the feature behaves,
> because it combines two functions that IMO shouldn't.
>
> Anyway the submitted patch is an improvement to the current status.
>
> --
> Fabien.