Re: Emacs completion matches selection UI

[Toby Cubitt]

On Fri, Jan 03, 2014 at 02:32:40PM -0500, Stefan Monnier wrote:
> >> > (Though I don't think the `completion-at-point' mechanism is really rich
> >> > enough to let Predictive do its stuff properly; in particular updating
> >> > the frequency data after completing.)
> >> Seems that :exit-function can be used for this. See 
> >> `completion-extra-properties'.
> > Thanks for the pointer. Unfortunately this isn't enough. In a typical
> > predictive-mode scenario, there are many possible completion candidates,
> > and Predictive needs to display them, and be told which of the candidates
> > was selected (or rejected).
> 
> I suspect that :exit-function is "enough", tho it might require some
> ugly unreliable hacks to get at the needed data.  Please try it out and
> M-x report-emacs-bug requesting the extra features/data to be able to
> "do it right".

I still don't see how, if by "enough" you mean enough to emulate the
current Predictive functionality without effectively bypassing the
`completion-at-point' mechanism and running Predictive/Completion-UI code
instead. `completion-at-point' is designed around "tab-completion", and
that just isn't a good match for predictive completion (or a popup.el
style UI, for that matter).

Anyway, I think we basically agree: at the moment
`completion-in-region-functions' and `completion-extra-properties' aren't
enough to implement something like Predictive without ugly hacks. I also
think if we can design a good generic Emacs completion UI and API, these
issues will go away.

Toby
-- 
Dr T. S. Cubitt
Royal Society University Research Fellow
and Fellow of Churchill College, Cambridge
Centre for Quantum Information
DAMTP, University of Cambridge

email: address@hidden
web:   www.dr-qubit.org