From: storm@cua.dk (Kim F. Storm)
Cc: emacs-devel@gnu.org
Subject: Re: Enhancements to "minor-mode-map-alist" functionality.
Date: 12 Apr 2002 23:05:23 +0200 [thread overview]
Message-ID: <5xy9fsocfg.fsf@kfs2.cua.dk> (raw)
In-Reply-To: <200204121820.g3CIKkA16739@rum.cs.yale.edu>
"Stefan Monnier" <monnier+gnu/emacs@rum.cs.yale.edu> writes:
>
> > But if we could support something like (keymap :filter fun ...),
> > it would satisfy the needs for cua.
>
> I had something like that working in the past. I don't think
> I have the code around any more, tho. IIRC it wasn't too difficult
> to add. The evaluation of the function was done in `get_keymap'
> (this is not to say that it was the right place to do it, but that
> it was my choice at the time, because it seemed simpler).
I'll give it a try...
>
> Another idea I have been toying with (but it never got far enough
> for me to start writing any code, not even tentatively) is to use
> a "null event". Assuming this event is called `nil', you could
> replace the above dynamic keymap with:
>
> (defvar dynmap (make-sparse-keymap))
> (define-key dynmap [nil] '(menu-item "foo" data :filter fun))
>
> Ideally this would also allow multiple such "same-level submaps"
> which would then provide multiple keymap inheritance.
>
This is very similar to my new proposal for nested keymaps, but
it looks like a hack to use menu-item that way.
> > > So if the dynamism you need is only in the `command-remap' submap,
> > > for example, your new hack is not needed.
> > I don't think this is a hack!
>
> I said "hack" because I think it's more ad-hoc than it should.
>
> > ;; Neat trick from Dave Love to add more bindings in read-only mode:
> > (add-to-list 'minor-mode-map-alist
> > `(lambda . (and diff-minor-mode buffer-read-only
> > '(diff-minor-mode . ,diff-mode-shared-map))))
>
> Indeed.
>
> > ;; View mode steals RET from us.
> > (local-set-key [remap View-scroll-line-forward] 'help-follow)
>
> That one looks completely bogus to me. Do you really want to prevent
> the use of View-scroll-line-forward from a help-mode buffer even if
> it's bound to something else than RET ?
No, that wasn't the intention ... I must have been sleeping...
>
> > [Actually, I think I'll install that change in any case].
>
> Please don't.
I wont.
But I still think the use of the minor-mode-overriding-map-alist for
this purpose is pretty obscure (although I suspect that is the
purpose for which it was invented...)
An alternative would be to put a keymap property on the link
like this: [in CVS emacs, keymap properties take precedence over
minor mode keymaps!]
(defun help-xref-button (match-number type &rest args)
"Make a hyperlink for cross-reference text previously matched.
MATCH-NUMBER is the subexpression of interest in the last matched
regexp. TYPE is the type of button to use. Any remaining arguments are
passed to the button's help-function when it is invoked.
See `help-make-xrefs'."
;; Don't mung properties we've added specially in some instances.
(unless (button-at (match-beginning match-number))
(make-text-button (match-beginning match-number)
(match-end match-number)
'type type 'help-args args 'keymap help-mode-map)))
^^^^^^^^^^^^^^^^^^^^^
>
> > > I'd rather not add a hack that's specific to minor-mode-map-alist
> > > if we could do the same for all cases instead.
> >
> > Sure. But what device do you suggest then?
> > (keymap :filter fun ...) ?
> >
> > I don't object to that, but it would be _less_ efficient, since
> > we have to search the keymap for the :filter property (like we do
> > for a menu-item, but that is much shorter) [unless we ensure
> > it stays at the head of the keymap list].
>
> I don't care much for efficiency at this stage.
Neither do I !!
>
> > Also, the keymap lookup code would also have to be careful not to
> > interpret the FUN part as a binding,
>
> You can force it to be a symbol.
I would prefer not to do that; an alternative would be to put a
cons cell (:filter . FORM) into the keymap, causing the rest of
the keymap to be ignored if FORM returns nil.
Along this line, we could also add (lambda . FORM) in a keymap which
will evaluate FORM to get a nested keymap.
>
> > and when we add binding to
> > a map, we should be careful not to split the ":filter FUN" pair.
>
> Of course, it might need some care. Doing it in get_keymap works
> around the above problem, tho since the keymap that's modified
> is the one returned by get_keymap.
I guess using (:filter . FORM) would make it easier to ensure this.
>
> > So GC-wise this only makes things marginally worse :-/
>
> I'd rather try to make it better than to make it marginally worse.
Sure.
>
> > > In other words, maybe we shouldn't evaluate the form inside this
> > > current_minor_maps function.
> > I still think it is pretty safe to do so.
>
> Despite the comment that's just above ? Do you really think the
> coders went to the trouble of not using xmalloc/xrealloc and of
> sometimes returning an incorrect result (hoping that the cause of
> the problem will cause something else to abort later on) just
> for the fun of it ?
You are right. I overlooked the finer details of that comment.
>
> > If some packages decide to fiddle with minor-mode-map-alist when you
> > activate the mode the first time (rather than on load), I don't
> > think an after-load-hook will catch that.
>
> And if some package decides to fiddle with it from an idle-hook, the
> post-command-hook will fail as well. The question is not "is it theoretically
> safe" but "is it safe in practice" ? I believe it'd be good enough in practice
> because I don't see much fiddling of minor-mode-map-alist outside of
> toplevel expressions.
I would be much easier if an element in the minor-mode-map-alist
could be tagged as `keep at head of list'. IIRC we discussed this
some time ago on this list, and really didn't find a way to
accomplish that.
But maybe such modes could simply put their map on
minor-mode-overriding-map-alist instead ? Is that "legal practice"?
--
Kim F. Storm <storm@cua.dk> http://www.cua.dk
next prev parent reply other threads:[~2002-04-12 21:05 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-04-11 22:56 Enhancements to "minor-mode-map-alist" functionality Kim F. Storm
2002-04-11 22:43 ` Stefan Monnier
2002-04-12 9:31 ` Kim F. Storm
2002-04-12 13:20 ` Kim F. Storm
2002-04-12 18:46 ` Stefan Monnier
[not found] ` <5xofgoobzr.fsf@kfs2.cua.dk>
[not found] ` <200204122021.g3CKLh217680@rum.cs.yale.edu>
2002-04-14 22:32 ` Kim F. Storm
2002-04-16 20:18 ` Richard Stallman
2002-04-16 22:34 ` Kim F. Storm
2002-04-18 18:46 ` Richard Stallman
2002-04-18 23:07 ` Kim F. Storm
2002-04-19 13:43 ` Stefan Monnier
2002-04-19 15:36 ` Kim F. Storm
2002-04-19 14:46 ` Stefan Monnier
2002-04-21 17:46 ` Kim F. Storm
2002-04-22 9:28 ` Stefan Monnier
2002-04-22 15:15 ` Kim F. Storm
2002-04-19 18:42 ` Richard Stallman
2002-04-19 22:05 ` Kim F. Storm
2002-04-20 17:27 ` Richard Stallman
2002-04-21 11:08 ` Kim F. Storm
2002-04-22 7:47 ` Richard Stallman
2002-04-22 13:53 ` Kim F. Storm
2002-04-22 22:36 ` Richard Stallman
2002-04-23 10:58 ` Kim F. Storm
2002-04-22 22:36 ` Richard Stallman
2002-04-23 11:02 ` Kim F. Storm
2002-04-24 17:55 ` Richard Stallman
2002-04-26 13:44 ` Kim F. Storm
2002-04-27 22:41 ` Richard Stallman
2002-04-29 9:17 ` Kai Großjohann
2002-04-30 5:18 ` Richard Stallman
2002-04-30 21:25 ` Kim F. Storm
2002-05-01 7:14 ` Richard Stallman
2002-05-01 17:37 ` Kim F. Storm
2002-04-14 23:11 ` Kim F. Storm
2002-04-12 18:20 ` Stefan Monnier
2002-04-12 21:05 ` Kim F. Storm [this message]
2002-04-12 20:30 ` Stefan Monnier
2002-04-12 22:08 ` Kim F. Storm
2002-04-13 19:05 ` Richard Stallman
2002-04-13 19:05 ` Richard Stallman
2002-04-13 23:30 ` Kim F. Storm
2002-04-15 12:34 ` Stefan Monnier
2002-04-17 16:03 ` Richard Stallman
2002-04-15 21:54 ` Richard Stallman
2002-04-15 23:55 ` Kim F. Storm
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