Re: master 3b41141708: Expose the name of an event's input device to Lisp

[Eli Zaretskii <eliz@gnu.org>]

> From: Po Lu <luangruo@yahoo.com>
> Cc: monnier@iro.umontreal.ca,  emacs-devel@gnu.org
> Date: Sun, 10 Apr 2022 15:37:30 +0800
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > We have this in many places in Emacs already, so adding one more will
> > not hurt too much.  Dispatch on the first element of the list is easy
> > and produces code that is quite readable and maintainable, IMO.
> >
> > Of course, if more elegant ways exist, I don't object to using them,
> > quite the contrary.  But if not, I see nothing especially wrong with
> > doing what you call "very confusing", because we do it elsewhere.
> 
> Hmm, do we use keywords anywhere inside Lisp events?  If not, then
> here's a simple way to add a property list to the end of event lists:
> 
>   (defun event-plist (event)
>     "Return the property list of EVENT."
>     (while (and event (not (keywordp (car event))))
>       (setq event (cdr event)))
>     event)
> 
> Then, additional information could just be added to the end of each
> event by appending any property list that associates keywords.

It's possible.  But using ordered lists is also OK.

Having keyword/value pairs would probably call for a new kind of event
list, so that applications could know whether to use indexed access or
keyword-based access.