bug#11929: 24.1.50; Globalized minor mode turn-on function is called twice for each opened file

bug#11929: 24.1.50; Globalized minor mode turn-on function is called twice for each opened file

[Dmitry Gutov]

I raised the topic on help-gnu-emacs previously, but hadn't received an
answer: 
http://lists.gnu.org/archive/html/help-gnu-emacs/2012-07/msg00174.html

How to reproduce.

1. Define the minor mode:

(define-minor-mode foo-mode "" :lighter "")

(defun turn-on-foo-mode ()
   (message "buffer %s major mode %s" (buffer-name) major-mode)
   (foo-mode 1))

(define-globalized-minor-mode global-foo-mode foo-mode turn-on-foo-mode)

2. Turn on the global mode.

3. Open any file, look at the *Messages* buffer.
It will contain something like this:

buffer init.el major mode fundamental-mode
buffer init.el major mode emacs-lisp-mode

If the buffer is going to be immediately switched to another mode,
there's no point in calling the turn-on function in the default mode.
I think this behavior is buggy.

--Dmitry

In GNU Emacs 24.1.50.1 (i386-mingw-nt6.1.7601)
  of 2012-07-11 on SOL
Windowing system distributor `Microsoft Corp.', version 6.1.7601
Configured using:
  `configure --with-gcc (3.4) --cflags -IH:/Apps/System/gnuwin32/include'

Important settings:
   value of $EMACSDATA: C:/Users/gutov/vc/emacs-master/etc
   value of $EMACSDOC: C:/Users/gutov/vc/emacs-master/etc
   value of $EMACSLOADPATH: 
C:/Users/gutov/vc/emacs-master/site-lisp;C:/Users/gutov/vc/emacs-master/../site-lisp;C:/Users/gutov/vc/emacs-master/lisp;C:/Users/gutov/vc/emacs-master/leim
   value of $EMACSPATH: C:/Users/gutov/vc/emacs-master/bin
   value of $LANG: RU
   locale-coding-system: cp1251
   default enable-multibyte-characters: t

bug#11929: 24.1.50; Globalized minor mode turn-on function is called twice for each opened file

[Lars Ingebrigtsen]

Dmitry Gutov <dgutov@yandex.ru> writes:

> 1. Define the minor mode:
>
> (define-minor-mode foo-mode "" :lighter "")
>
> (defun turn-on-foo-mode ()
>   (message "buffer %s major mode %s" (buffer-name) major-mode)
>   (foo-mode 1))
>
> (define-globalized-minor-mode global-foo-mode foo-mode turn-on-foo-mode)
>
> 2. Turn on the global mode.
>
> 3. Open any file, look at the *Messages* buffer.
> It will contain something like this:
>
> buffer init.el major mode fundamental-mode
> buffer init.el major mode emacs-lisp-mode
>
> If the buffer is going to be immediately switched to another mode,
> there's no point in calling the turn-on function in the default mode.
> I think this behavior is buggy.

If I understand you correctly, you don't think that buffers should first
be opened in `fundamental-mode', and then the "real" major mode, because
this means that globalised minor modes get switched on twice?

I agree that this seems like surprising behaviour, but I think it's been
this way since forever, so perhaps it should just be documented?  I'm
not sure where, though...  in the `define-globalized-minor-mode' doc
string, perhaps?

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