GNU bug report logs -
#3394
23.0.94; define-derived-mode keymap inheritance
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Reported by: "Drew Adams" <drew.adams <at> oracle.com>
Date: Tue, 26 May 2009 22:20:03 UTC
Severity: normal
Done: Stefan Monnier <monnier <at> iro.umontreal.ca>
Bug is archived. No further changes may be made.
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This is an automatic notification regarding your bug report
which was filed against the emacs package:
#3394: 23.0.94; define-derived-mode keymap inheritance
It has been closed by Stefan Monnier <monnier <at> iro.umontreal.ca>.
Their explanation is attached below along with your original report.
If this explanation is unsatisfactory and you have not received a
better one in a separate message then please contact Stefan Monnier <monnier <at> iro.umontreal.ca> by
replying to this email.
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3394: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=3394
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> I know that there is no guarantee (quite the opposite) that code
> byte-compiled in Emacs 20 will work in Emacs 23. But I wonder if there
> might be a bug here anyway, wrt the keymap inheritance. If not, OK. In
Well, yes, there was a bug in Emacs-20's implementation of
define-derived-mode. Not much we can do about it, I'm afraid.
Stefan
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Reporting this as a bug just in case it is. I don't know.
I have a file that requires `buff-menu.el', then does this, to
redefine `Buffer-menu-mode'.
(when (> emacs-major-version 22)
(put 'Buffer-menu-mode 'mode-class 'special)
(define-derived-mode Buffer-menu-mode special-mode "Buffer Menu"
"..."
(set (make-local-variable 'revert-buffer-function)
'Buffer-menu-revert-function)
(set (make-local-variable 'buffer-stale-function)
#'(lambda (&optional noconfirm) 'fast))
(setq truncate-lines t)
(setq buffer-read-only t)))
That definition is actually identical to the original definition in
buff-menu.el. (In reality, my code adds a bit to the original
definition, but the problem occurs also with just the code above.
If I byte-compile the file in Emacs 22 or 23, which have
`define-derived-mode', then there is no problem. (Likewise, if
I load the *.el file instead of the *.elc.)
If I byte-compile in Emacs 20 (which does not have
`define-derived-mode'), then everything still works as usual,
except for one thing: The keymap for `special-mode' is apparently
not inherited. So for example, `q' and `g' have no key bindings
in the *Buffer List*.
By eyeballing it, the *.elc file would seem to be picking up the
`define-derived-mode' code as if it were a top-level function call,
which is what I would expect. I assume that the macro is defined when
the *.elc is loaded, so I would expect that `define-derived-mode'
would do its thing normally when the *.elc is loaded.
I know that there is no guarantee (quite the opposite) that code
byte-compiled in Emacs 20 will work in Emacs 23. But I wonder if there
might be a bug here anyway, wrt the keymap inheritance. If not, OK. In
that case, I'm just a bit curious what's happening - why everything
else seems to work fine, but the `special-mode' keymap doesn't seem to
be inherited.
In GNU Emacs 23.0.94.1 (i386-mingw-nt5.1.2600)
of 2009-05-24 on SOFT-MJASON
Windowing system distributor `Microsoft Corp.', version 5.1.2600
configured using `configure --with-gcc (3.4)'
This bug report was last modified 15 years and 363 days ago.
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