On Fri, Jul 12, 2024 at 02:53:36PM +0200, Robert Pluim wrote:
> >>>>> On Fri, 12 Jul 2024 08:14:52 -0400, Pierre Rouleau <prouleau001@gmail.com> said:
> 
>     Pierre>  Hi all,
>     Pierre> Does Emacs already have a predicate function that can be used to check if
>     Pierre> the specified key sequence is valid for Emacs running in terminal mode?
> 
> Not that I know of, but Emacs always has functionality I donʼt know of
> :-)
> 
>     Pierre> For example, "C-;" is not accessible on Emacs running in terminal mode
>     Pierre> because this is not an ASCII control character. It's available for Emacs
>     Pierre> running in graphical environment, but not in terminal mode.
> 
>     Pierre> Is there something similar already available or one would simply wrap
>     Pierre> describe-key and catch the error to check?
> 
> Iʼm in a terminal frame:
> 
>     (describe-key (kbd "C-;")) =>
>     #("C-; is undefined" 0 3 (face help-key-binding font-lock-face help-key-binding))
> 
> which is exactly what you get in a GUI frame.
> 
> I think the best you can do is bind the key. If itʼs available, it will work.

OK, negatively speaking, on a terminal CTRL zeros bit 6 (counting from LSB,
starting with 0) to reach the control codes 0..1f (hex). So it only makes
sense with the character codes 40..5f hex (that's '@'..'_').

Everything else is probably GUIsh.

Cheers
-- 
t