GNU bug report logs - #29081
25.1; define-globalized-minor-mode does not respect :variable of original mode

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: k <at> rdw.se (Chris Stj)
To: bug-gnu-emacs <at> gnu.org
Subject: 25.1;
 define-globalized-minor-mode does not respect :variable of original
 mode
Date: Tue, 31 Oct 2017 13:29:57 +0100

I tried to define a global version of auto-fill mode by evaluating

  (define-globalized-minor-mode global-auto-fill-mode auto-fill-mode
    turn-on-auto-fill)

The problem is that when the define-globalized-minor-mode macro expands,
it defines the function

       (defun ,MODE-enable-in-buffers ()
	 (dolist (buf ,MODE-buffers)
	   (when (buffer-live-p buf)
	     (with-current-buffer buf
               (unless ,MODE-set-explicitly
		 (unless (eq ,MODE-major-mode major-mode)
		   (if ,mode
		       (progn
			 (,mode -1)
			 (funcall #',turn-on))
		     (funcall #',turn-on))))
	       (setq ,MODE-major-mode major-mode)))))

The problem lies in the "if ,mode" condition. This assumes the minor
mode variable has the same name as the minor mode itself; which is
clearly not true when something else is specified with the :variable
keyword in the minor mode definition.

I noticed this with auto-fill-mode, since it calls its status variable
auto-fill-function rather than auto-fill-mode.

I guess the best solution may be to allow users of
define-globalized-minor-mode to specify the place in which the minor
mode stores its state, since I can't find a good, generic way to extract
this from the minor mode definition itself, after the fact.

Regards,
Chris

Message #8 received at 29081 <at> debbugs.gnu.org (full text, mbox):

From: Noam Postavsky <npostavs <at> users.sourceforge.net>
To: k <at> rdw.se (Chris Stj)
Cc: 29081 <at> debbugs.gnu.org
Subject: Re: bug#29081: 25.1;
 define-globalized-minor-mode does not respect :variable of original
 mode
Date: Sat, 02 Dec 2017 14:04:26 -0500

tags 29081 + confirmed easy
quit

k <at> rdw.se (Chris Stj) writes:

> The problem lies in the "if ,mode" condition. This assumes the minor
> mode variable has the same name as the minor mode itself; which is
> clearly not true when something else is specified with the :variable
> keyword in the minor mode definition.

> I guess the best solution may be to allow users of
> define-globalized-minor-mode to specify the place in which the minor
> mode stores its state, since I can't find a good, generic way to extract
> this from the minor mode definition itself, after the fact.

Makes sense to me.

Message #13 received at 29081 <at> debbugs.gnu.org (full text, mbox):

From: Lars Ingebrigtsen <larsi <at> gnus.org>
To: Noam Postavsky <npostavs <at> users.sourceforge.net>
Cc: 29081 <at> debbugs.gnu.org, Chris Stj <k <at> rdw.se>
Subject: Re: bug#29081: 25.1; define-globalized-minor-mode does not respect
 :variable of original mode
Date: Thu, 04 Feb 2021 15:23:02 +0100

Noam Postavsky <npostavs <at> users.sourceforge.net> writes:

>> I guess the best solution may be to allow users of
>> define-globalized-minor-mode to specify the place in which the minor
>> mode stores its state, since I can't find a good, generic way to extract
>> this from the minor mode definition itself, after the fact.
>
> Makes sense to me.

Me too, so I've added this to Emacs 28.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

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