From: Stefan Monnier <monnier@IRO.UMontreal.CA>
To: Eli Zaretskii <eliz@gnu.org>
Cc: emacs-devel@gnu.org
Subject: Re: locate-dominating-file calls `stat' too eagerly
Date: Mon, 29 Sep 2008 12:19:15 -0400 [thread overview]
Message-ID: <jwv1vz3djbf.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: <uzllrj9x6.fsf@gnu.org> (Eli Zaretskii's message of "Mon, 29 Sep 2008 17:36:53 +0300")
> That would work as well, but I'm not sure about the ``simpler'' part.
It's definitely a simpler change, which means it's probably safer.
> The code is already pretty convoluted, and I'm not sure why. All it
> needs to do is (1) to find an existing parent directory of its
> argument FILE by chopping directories from the end until it finds an
> existing one, and (2) go up the tree of existing directories until it
> finds one whose owner is different. This looks like 2 separate loops
> to me, but the code for some reason insists on doing it in a single
> loop.
I think it's mostly a historical accident, but it's also so that both
loops get the other's fixes.
> How about this:
> (defun locate-dominating-file (file regexp)
> "Look up the directory hierarchy from FILE for a file matching REGEXP."
> ;; If FILE does not exist, find its parent directory that does.
> (or (file-exists-p file)
> (while (and file (not (file-directory-p file)))
> (setq file (file-name-directory (directory-file-name file)))))
In some corner cases, this can infloop.
That's why we do (if (equal dir (setq dir ...)) ...) test in the
main loop.
IIRC I wrote pretty much the above loop at some point and when faced
with those issues I figured it was preferable to reuse the main loop so
as to reuse all the experience it embodies.
> And btw, won't the user test cover the case of crossing ~/ as well?
In 99% of the cases, yes.
> If so, we don't need to abbreviate-file-name, which then incurs
> further overhead inside expand-file-name.
This overhead should be negligible. Furthermore, I'm not sure whether
we'll keep the user-test since it is incompatible with some (rare)
usage patterns.
Stefan
next prev parent reply other threads:[~2008-09-29 16:19 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-09-29 11:54 locate-dominating-file calls `stat' too eagerly Eli Zaretskii
2008-09-29 14:06 ` Stefan Monnier
2008-09-29 14:36 ` Eli Zaretskii
2008-09-29 16:19 ` Stefan Monnier [this message]
2008-09-29 19:05 ` Eli Zaretskii
2008-09-29 20:45 ` Stefan Monnier
2008-09-30 7:14 ` Eli Zaretskii
2008-09-30 14:02 ` Stefan Monnier
2008-09-30 16:30 ` Eli Zaretskii
2008-09-30 12:52 ` Eli Zaretskii
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