From: Aaron Ecay <aaronecay@gmail.com>
To: Bastien <bzg@gnu.org>, Stefan Monnier <monnier@iro.umontreal.ca>
Cc: emacs-devel@gnu.org
Subject: Re: Using `save-window-excursion' instead of `save-excursion' for `comment-region'?
Date: Thu, 05 Dec 2013 14:05:37 -0500 [thread overview]
Message-ID: <87fvq7dsou.fsf@gmail.com> (raw)
In-Reply-To: <87ob4vuoi8.fsf@bzg.ath.cx>
2013ko abenudak 5an, Bastien-ek idatzi zuen:
>
> This is how it works:
>
> comment-region calls comment-region-function within save-excursion
> (assuming there is no window change.)
>
> comment-region-function calls org-babel-do-in-edit-buffer which
> inserts the source code in another buffer, then calls back again
> comment-region with comment-region-function bound to the correct
> mode-dependent function.
>
> The "outward" comment-region does not restore the point position
> correctly.
>
> So I'm not sure why save-window-excursion would only works "by
> accident" here. I cannot think of a better fix right now, I'll
> continue to travel through the Babel maze.
I think the problem is that org-babel-do-in-edit-buffer deletes the
whole contents of the source code block, and re-inserts it. This means
that the marker that save-excursion uses (pointing to somewhere in the
deleted and re-inserted span) no longer points to the desired position,
but rather to just before the span.
Org babel has its own point-restoration functionality (which works by
counting lines and columns), but this is executed inside of the scope of
comment-region’s save-excursion, so exiting the latter restores the
point to a bogus position (from the POV of the user).
--
Aaron Ecay
next prev parent reply other threads:[~2013-12-05 19:05 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-05 10:18 Using `save-window-excursion' instead of `save-excursion' for `comment-region'? Bastien
2013-12-05 11:46 ` martin rudalics
2013-12-05 12:49 ` Andreas Röhler
2013-12-05 18:29 ` Stefan Monnier
2013-12-05 18:43 ` Bastien
2013-12-05 19:05 ` Aaron Ecay [this message]
2013-12-05 19:45 ` Stefan Monnier
2013-12-06 9:49 ` Bastien
2013-12-06 9:58 ` Bastien
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