Mapping ESC to Cancel in terminal emacs

Mapping ESC to Cancel in terminal emacs

[Craig Muth]

I added some elisp to the following emacswiki page that gets somewhat
close to making ESC behave like C-g.  It uses a small cua-mode-like
delay to distinguish using ESC as a prefix key from an ESC to cancel:

http://www.emacswiki.org/emacs/CancelingInEmacs

Anyone know of a better way to put something like "\eb" back into
unread-command-events, so it replicate the state before the event was
read?  Here's a relevant blurb I added at the bottom of the emacswiki
page:

-------------------------------------------------------------------
One drawback, though, is that it messes up C-h C-k, making it think
the key you typed was only escape. Does anyone know of a better way of
putting the escape and the subsequent key back into effect than the
following? Maybe a way that makes it not treat the escape separately?

      (setq unread-command-events (cons event unread-command-events))
 ; Puts subsequent key back into effect
      (setq unread-command-events (cons 27 unread-command-events))   ;
Puts escape back into effect
-------------------------------------------------------------------

Caveat: I do fully realize that making escape work like C-g in a
general way is a bad idea. I have in mind the exceptional case where
emacs is used as an engine, or when you're temporarily remapping
escape while pairing with a user who isn't yet familiar with emacs.

Thanks!
--Craig

Re: Mapping ESC to Cancel in terminal emacs

[David Kastrup]

Craig Muth <craig.muth@gmail.com> writes:

> I added some elisp to the following emacswiki page that gets somewhat
> close to making ESC behave like C-g.

You are aware that ESC ESC ESC aborts pretty much anywhere that C-g
aborts, with the exception of the terminal layer (interrupting running
Elisp) which you probably cannot sensibly tamper with anyway?

-- 
David Kastrup

Re: Mapping ESC to Cancel in terminal emacs

[Stefan Monnier]

> Anyone know of a better way to put something like "\eb" back into
> unread-command-events, so it replicate the state before the event was
> read?

Before trying to answer such a question, you should ask yourself whether
there's a way to get what you want *without* needing to put things back
on unread-command-events (i.e. so the event is only consumed when you
need to consume it).

I think if you use key remapping, such as input-decode-map, you can get
what you want.  Look for that variable in lisp/emulation/viper.el to see
how Viper handles VI's escape key, for example.


        Stefan