Re: M-x mystery

[Silvio Levy]

Thank Teemu. I understand there are historical constraints. But note
that I'm not using the emacs GUI at all. I'm just talking about the
keyboard, and I thought alt-x is treated by keyboards in a way that's
exactly parallel to ctrl-x. 

I do see that saying (define-key global-map "\M-x" 'kill-line) after
I've redefined ESC generates the complaint "Key sequence M-x starts
with non-prefix key".  

I'm studying the references Drew sent in the Elisp manual, `Functions
for Key Lookup' and `Other Char Bits'. Obviously there are many
subtleties I wasn't aware of.

Best wishes,

Silvio


> From: Teemu Likonen <tlikonen@iki.fi>
> To: Silvio Levy <levy@msri.org>
> Cc: Drew Adams <drew.adams@oracle.com>, help-gnu-emacs@gnu.org
> Subject: Re: M-x mystery
> References: <20120102173715.D8C94180B85@neo.msri.org>
> Date: Mon, 02 Jan 2012 21:40:57 +0200
> In-Reply-To: <20120102173715.D8C94180B85@neo.msri.org> (Silvio Levy's message
>       of "Mon, 02 Jan 2012 09:37:15 -0800")
> 
> * 2012-01-02T09:37:15-08:00 * Silvio Levy wrote:
> 
> > And that's what I don't understand. It's one thing for <ESC> x to be
> > treated as M-x because some people lack that alt key, but for emacs to
> > *convert* the keycode <alt>x to <ESC> x seems to me like poor design.
> 
> That's a historical Unix text terminal thing. All input must have a
> "slot" in the current character set. That is, everything must be a
> character (code). There is this concept of Meta key which is produced by
> Esc in today's keyboards. Its Ascii code is 27 so it's a character (kind
> of).
> 
> If we want to use Alt key in text terminals we must decide which
> character (code) it produces. Well, the choice has already been made for
> us. Alt+x was chosen to insert Meta x so that it's easier to type those
> Meta key combinations.
> 
> Emacs in Unix text terminals is tied to this design of text terminals
> (remember, you can use them through a modem/serial line). Emacs's
> graphical user interface does not _need_ to be as limited but apparently
> developers want it to be as compatible as possible anyway - and I agree
> with them.