From: Eli Zaretskii <eliz@gnu.org>
To: oscarfv@telefonica.net (Óscar Fuentes)
Cc: michael_heerdegen@web.de, 23902@debbugs.gnu.org
Subject: bug#23902: 25.1.50; Strange warning on string-collate-equalp's docstring
Date: Sun, 10 Jul 2016 05:40:25 +0300 [thread overview]
Message-ID: <83oa66fc6e.fsf@gnu.org> (raw)
In-Reply-To: <87eg72cx3u.fsf@wanadoo.es> (oscarfv@telefonica.net)
> From: oscarfv@telefonica.net (Óscar Fuentes)
> Cc: Glenn Morris <rgm@gnu.org>, michael_heerdegen@web.de, 23902@debbugs.gnu.org
> Date: Sat, 09 Jul 2016 23:36:37 +0200
>
> Eli Zaretskii <eliz@gnu.org> writes:
>
> > But they can reason this way instead:
> >
> > "I want to compare two file names.
> > Collation is a way to compare strings, for example the man page for
> > strcoll says the function returns zero if one string is equal to the
> > other.
> > And Emacs just learned how to use collation to compare strings, it
> > has this great new function string-collate-equalp.
> > Therefore, let's use string-collate-equalp for comparing two file
> > names."
>
> This implies that the user knows about string comparisons with collation
> but he is a complete ignoramus about file systems. A bit unrealistic.
I'm not sure. People might know a lot about strings, but not how the
filesystem stores file names.
> >> And suppose I have two strings, and want to know if they are equal,
> >> respecting my locale's convention about characters that are not
> >> literally identical, but have the same meaning. I should use
> >> string-collate-equalp for this. This is true whether the strings
> >> represent the names of elephants in a zoo, or files on a disk.
> >
> > And that is exactly the fallacy that the note warns against. Because
> > filesystems don't compare as equal characters that have the same
> > meaning, they compare bytes in a byte stream that is the file name in
> > its raw byte form, as recorded on disk.
>
> I think that Glenn is saying that you can compare file names for other
> purposes than knowing if they name the same file.
Then it's not "equality", it's "equivalence".
next prev parent reply other threads:[~2016-07-10 2:40 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-05 22:05 bug#23902: 25.1.50; Strange warning on string-collate-equalp's docstring Óscar Fuentes
2016-07-06 14:34 ` Eli Zaretskii
2016-07-06 15:08 ` Michael Heerdegen
2016-07-06 15:28 ` Eli Zaretskii
2016-07-06 15:46 ` Óscar Fuentes
2016-07-06 16:26 ` Eli Zaretskii
2016-07-06 17:44 ` Óscar Fuentes
2016-07-06 18:32 ` Eli Zaretskii
2016-07-09 17:06 ` Glenn Morris
2016-07-09 17:21 ` Eli Zaretskii
2016-07-09 21:36 ` Óscar Fuentes
2016-07-10 2:40 ` Eli Zaretskii [this message]
2016-07-10 3:06 ` Michael Heerdegen
2016-07-10 14:40 ` Eli Zaretskii
2016-07-06 15:55 ` Michael Heerdegen
2016-07-06 16:30 ` Eli Zaretskii
2016-07-06 16:44 ` Michael Heerdegen
2016-07-06 17:18 ` Eli Zaretskii
2016-07-06 22:49 ` Michael Heerdegen
2016-07-07 2:38 ` Eli Zaretskii
2016-07-07 21:52 ` Michael Heerdegen
2016-07-08 10:11 ` Eli Zaretskii
2016-07-08 20:59 ` Michael Heerdegen
2016-07-09 6:52 ` Eli Zaretskii
2016-07-09 17:06 ` Richard Stallman
2016-07-09 22:59 ` Michael Heerdegen
2016-07-06 15:48 ` Glenn Morris
2016-07-06 16:27 ` Eli Zaretskii
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