keys with meta-prefix cannot be longer than two chars?

keys with meta-prefix cannot be longer than two chars?

[Artur Malabarba]

The following is quoted from the header comments in isearch.el

;; The key bindings active within isearch-mode are defined below in
;; `isearch-mode-map' which is given bindings close to the default
;; characters of the original isearch.el.  With `isearch-mode',
;; however, you can bind multi-character keys and it should be easier
;; to add new commands.  One bug though: keys with meta-prefix cannot
;; be longer than two chars.

That last sentence is intriguing. I tested with this snippet and it
didn't hold true for me.
    (define-key isearch-mode-map "\M-6lo" (lambda () (interactive)
(message "HI")))

Does anyone know its origin and may I delete it?

Re: keys with meta-prefix cannot be longer than two chars?

[John Wiegley]

>>>>> Artur Malabarba <bruce.connor.am@gmail.com> writes:

> One bug though: keys with meta-prefix cannot be longer than two chars.

> That last sentence is intriguing. I tested with this snippet and it didn't
> hold true for me. (define-key isearch-mode-map "\M-6lo" (lambda ()
> (interactive) (message "HI")))

> Does anyone know its origin and may I delete it?

I don't know its origin. If no one else pipes up, and you've demonstrated it
works, please do delete.

John

Re: keys with meta-prefix cannot be longer than two chars?

[Eli Zaretskii]

> From: "John Wiegley" <johnw@newartisans.com>
> Date: Wed, 21 Oct 2015 09:45:08 -0700
> 
> >>>>> Artur Malabarba <bruce.connor.am@gmail.com> writes:
> 
> > One bug though: keys with meta-prefix cannot be longer than two chars.
> 
> > That last sentence is intriguing. I tested with this snippet and it didn't
> > hold true for me. (define-key isearch-mode-map "\M-6lo" (lambda ()
> > (interactive) (message "HI")))
> 
> > Does anyone know its origin and may I delete it?
> 
> I don't know its origin. If no one else pipes up, and you've demonstrated it
> works, please do delete.

Note that it says "longer than two chars", and I wonder whether it
means excluding the prefix char.

Anyway, this comment was written by Richard (CC'ed), so perhaps he
could remember what was the intent, although it was very long ago.

Richard, this is about the following comment from isearch.el:

  ;;; Commentary:

  ;; Instructions

  ;; For programmed use of isearch-mode, e.g. calling (isearch-forward),
  ;; isearch-mode behaves modally and does not return until the search
  ;; is completed.  It uses a recursive-edit to behave this way.

  ;; The key bindings active within isearch-mode are defined below in
  ;; `isearch-mode-map' which is given bindings close to the default
  ;; characters of the original isearch.el.  With `isearch-mode',
  ;; however, you can bind multi-character keys and it should be easier
  ;; to add new commands.  One bug though: keys with meta-prefix cannot
  ;; be longer than two chars.^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
     ^^^^^^^^^^^^^^^^^^^^^^^^

Judging by the commit where this was added, it was some merge with an
isearch-related package that was absorbed into isearch.el.  You can
see the diffs with this command:

   git show 08200510