Re: Inline completion preview

[Eli Zaretskii <eliz@gnu.org>]

> From: João Távora <joaotavora@gmail.com>
> Date: Fri, 27 Oct 2023 12:49:40 +0100
> Cc: Eshel Yaron <me@eshelyaron.com>, emacs-devel@gnu.org
> 
> On Thu, Oct 26, 2023 at 7:38 PM Eli Zaretskii <eliz@gnu.org> wrote:
> >
> > > From: Eshel Yaron <me@eshelyaron.com>
> > > Date: Thu, 26 Oct 2023 20:11:17 +0200
> > >
> > > I want to propose adding an inline completion preview mechanism to Emacs.
> > >
> > > By inline completion preview, I mean an overlay that pop ups after point
> > > showing one of the candidates for at-point completion.  You can view
> > > this mechanism as giving you a hint or suggesting a certain completion.
> >
> > I wish people would work on adding to Emacs some a GUI infrastructure
> > for showing such completion candidates like other IDEs do, instead of
> > once again using overlays with after-string properties.  The result of
> > using overlay strings is simply not visually appealing, and on top of
> > that it causes quite a few complications for the display code.
> 
> I think agree with this, but it should work with Non-GUI Emacs, too right?

Ideally, yes.

> In a TUI Emacs, there have been these nice pop-up menus for a while.  At first
> sight the display infrastructure being used there seems suitable for showing
> completions, so I wonder if that infrastructure couldn't be refactored
> then reused
> for a completion popup in core.

The text-mode frames should preferably also support this, but we
should first think how to do that on GUI frames, and only afterwards
how to express the same feature on TTY frames.

I also don't see any catastrophe in having features that can only work
on GUI frames, although we should try to avoid that.  For example,
popup menus and dialog boxes were not supported on TTY frames for 2
decades, and we didn't consider that to be such a bad thing.  So we
could develop the feature discussed here on GUI, and then take the
next 2 decades to find a way of doing that on TTY.