[PATCH] Save and restore point explicitly in `notmuch-wash-toggle-invisible-action'.
Dmitry Kurochkin
dmitry.kurochkin at gmail.com
Tue May 24 13:43:20 PDT 2011
Hi Carl.
On Tue, 24 May 2011 13:20:56 -0700, Carl Worth <cworth at cworth.org> wrote:
> On Mon, 23 May 2011 19:29:46 +0400, Dmitry Kurochkin <dmitry.kurochkin at gmail.com> wrote:
> > Before the change, save-excursion was used to save the point.
> > But the restored position is affected by buffer modifications,
> > which results in jumping cursor. The patch saves and restores
> > point explicitly by using a variable instead of save-excursion.
>
> Dmitry,
>
> Thanks so much for the improvement to the button text! This will be a
> nice thing to add.
>
> But this patch confuses me. I can understand how a buffer-position
> variable can cause the cursor to jump. That's usually the kind of thing
> that can be fixed by switching from an integer position to a marker
> instead, (since markers are updated when the corresponding text is
> updated).
>
So we need to switch from marker to an integer position, right?
> But in this case, I don't see how:
>
> (let ((old-point (point)))
> ... code here ...
> (goto-char old-point))
>
> is distinct from:
>
> (save-excursion
> ... code here ...
> )
>
> except that save-excursion actually does the right thing in the case of
> abnormal exit (throw or error).
>
> Can you help me understand what I'm missing here?
>
Unfortunately, I am not an Emacs lisp expert. I just noticed that the
cursor jumps and did the first thing that came to mind. And it worked.
Now, looking at Emacs source code, save_excursion_save() uses
point_marker() to save the point. As you said above, markers are
updated when the corresponding text is updated. That explains why the
cursor jumps when using `save-excursion'.
On the other hand, `point' returns position as an integer. Which is
just what we need.
Regards,
Dmitry
> -Carl
>
> --
> carl.d.worth at intel.com
Non-text part: application/pgp-signature
More information about the notmuch
mailing list