Re: Physical keyboard events

[Eli Zaretskii]

> From: Yuri Khan <yuri.v.khan@gmail.com>
> Date: Thu, 31 Oct 2024 00:13:31 +0700
> Cc: manikulin@gmail.com, emacs-devel@gnu.org
> 
> On Wed, 30 Oct 2024 at 22:27, Eli Zaretskii <eliz@gnu.org> wrote:
> 
> > > From: Yuri Khan <yuri.v.khan@gmail.com>
> > > Date: Wed, 30 Oct 2024 13:28:20 +0700
> > > Cc: emacs-devel@gnu.org
> 
> > > I’m going to posit the hypothesis that the *only* command for which it
> > > makes sense to use the keysym of the current layout is
> > > ‘self-insert-command’.
> > >
> > > Everything else wants the keysym of “the” Latin-based layout if there
> > > is one and only one; the keycode if there is none; and some heuristic
> > > tiebreaker for the case where the user has more than one Latin-based
> > > layout configured.
> >
> > How do you suggest to arrange for a low-level keyboard interface to
> > know which kind of Emacs command attempted to read the keyboard?
> 
> Since it’s not clairvoyant, it would need to save enough information
> for the keymap lookup code downstream. Specifically (XKB/X11 case):
> state of modifiers, keycode, keysym according to the currently active
> group, and keysym according to the appropriate Latin-based group.
> 
> Then, at the time of keymap lookup:
> 
> * Look up the active modifiers + active group keysym.
>   * If this yields ‘self-insert-command’ or another command
> specifically whitelisted, return that.
> * Look up the active modifiers + keysym from the Latin-based group. Return 
> that.

How do you know which keymap to look up and for which character,
before you decide which character to produce?

> Test case: If a mode keymap binds both ‘/’ and ‘.’, and a key produces
> ‘/’ in the Latin layout and ‘.’ in Cyrillic layout, then the ‘/’
> command shall be executed regardless of whether Latin or Cyrillic
> layout is active.

What if '/' is bound to self-insert-command, but '.' to something
else: what do you return then?