Re: Alt as meta, except for certain keys, how?

[Kevin Rodgers <ihs_4664@yahoo.com>]

Ehud Karni wrote:

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> On Thu, 07 Aug 2003 12:38:54 -0600, Kevin Rodgers <ihs_4664@yahoo.com> wrote:
>>(keyboard-translate ?\M-7 ?|) doesn't work, because keyboard-translate-table
>>is a char-table, which only handles unmodified characters.
>>
> 
> You can find the character value of any key by the following function:
> 
> (defun get-char-value () "get decimal value of any key"
>   (interactive)
>        (let (char
>              desc)
>            (message "Type any char - " )
>            (setq char (read-event))
>            (if (not char)
>                (message "Non char event - no value")
>                (condition-case ()
>                    (setq desc (text-char-description char))
>                    (error
>                        (setq desc "(No description)")))
>                    (if (numberp char)
>                        (message "Character typed is %s, (octal=%03o, decimal=%d, hexa=%02x)"
>                                desc char char char)
>                        (message "Input typed is %s, not a number" (prin1-to-string char t))))))


Overkill.


> On my system it shows for Alt-7:
>   Character typed is "7", (octal=20000067, decimal=4194359, hexa=400037)


Just evaluate ?\M-7.  On my system, it is -134217673, which is the crux of the
problem: meta-modified characters may have a negative character code, and thus
may not be a valid index into a char-table.


> So if you do:
>   (define-key key-translation-map [4194359] "|")


key-translation-map takes character arguments, not (vector or string) keys:

wrong-type-argument integerp [-134217673]


> It will do what you want (in all modes and maps - including isearch).


But on my system, that signals an args-out-of-range error:

args-out-of-range #^[t nil nil nil ...] -134217673


> Because key-translation-map may not exist, you better protect yourself
> by adding the following (before the define-key command):
>   (if (not key-translation-map)
>       (make-sparse-keymap key-translation-map))

key-translation-map is now a char-table, not a keymap (see the Translating Input
node of the Emacs Lisp manual).

-- 
Kevin Rodgers