Re: Does code exist to check if a key sequence is valid for Emacs running in terminal mode?

[Pierre Rouleau]

On Fri, Jul 12, 2024 at 9:11 AM Yuri Khan <yuri.v.khan@gmail.com> wrote:

> On Fri, 12 Jul 2024 at 19:15, Pierre Rouleau <prouleau001@gmail.com>
> wrote:
>
> > Does Emacs already have a predicate function that can be used to check if
> > the specified key sequence is valid for Emacs running in terminal mode?
> >
> > For example, "C-;" is not accessible on Emacs running in terminal mode
> > because this is not an ASCII control character. It's available for Emacs
> > running in graphical environment, but not in terminal mode.
>
> This is probably not solvable because an advanced terminal can
> implement a protocol extension that represents arbitrary keys as
> escape sequences that can then be turned into Emacs key events using
> input-decode-map.
>
> You are correct, it depends on the terminal being used.
I was thinking of writing a function that would call describe-key
but setup the scope to output into a temporary buffer that it
would discard and catch error if the key described is not a
valid one.

It would therefore like to distinguish the 3 potential cases:
- the key sequence is bound
- the key sequence is not defined.
   Like "C-| is undefined" when tried in Emacs running in graphical mode.
- the key sequence is not defined, but reported via an error.
    Like "C-;" when tried under Emacs running in terminal mode
    inside a terminal that does not remap the C-; to some other escape
sequence.

That sounds feasible.  No?

(sent again, forgot to cc. the list).
-- 
/Pierre