GNU bug report logs - #966
keybinding involving Ctrl and Shift and letter

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Message #11 received at 966-done <at> emacsbugs.donarmstrong.com (full text, mbox):

From: xah lee <xah <at> xahlee.org>
To: Chong Yidong <cyd <at> stupidchicken.com>
Cc: 966-done <at> debbugs.gnu.org
Subject: Re: keybinding involving Ctrl and Shift and letter
Date: Wed, 17 Sep 2008 15:48:00 -0700

umm...

thanks for the answer.

I think there is still a problem, that is, inconsistency with the  
meta notation.

Namely, when defining a key with Ctrl or Meta with a Shift and a  
letter, when it is Meta,

(global-set-key (kbd "M-N") 'f)
works but
(global-set-key (kbd "M-S-n") 'f) does not work.

But with Ctrl, it is the the other way around.

Shouldn't emacs make "M-S-n" notation work and not "M-N", so that it  
is consistant with the Control?

In summary, the notation for a Meta/Control+Shift+‹letter›  
keybinding used in macro is not consistant. For Meta, "-N" is  
effective but for Control, "-S-n" is effective.

  Xah
∑ http://xahlee.org/

☄


On Sep 17, 2008, at 1:08 PM, Chong Yidong wrote:

> i'm trying to set keybindings for both Ctrl+n and Ctrl+Shift+n, by:
>
> (global-set-key (kbd "C-N") 'f1)
> (global-set-key (kbd "C-n") 'f2)
>
> however, that doesn't work.
> Emacs will take both Ctrl+Shift+n and Ctrl+Shift+n to be whichever is
> evaluated last. In this case, f2.
>
> But the following works:
>
> (global-set-key (kbd "C-S-n") 'f1)
> (global-set-key (kbd "C-n") 'f2)
>
> This seems to contradict with Meta's ways.

This is a legacy of ASCII.  Taking a look at an ASCII chart, you'll see
that ^A (control-a) through ^Z (control-z) map to ASCII codes 1 through
26, and these control keys are not case sensitive: control-a is
equivalent to control-A.

Emacs extends ASCII, which allows us to define things like C-] which are
not present in ASCII.  However, (kbd "C-N") and (kbd "C-n") still both
evaluate to ^N.

☄

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