From: Stefan Monnier <monnier@iro.umontreal.ca>
To: emacs-devel@gnu.org
Subject: Re: Why does dired go through extra efforts to avoid unibyte names
Date: Tue, 02 Jan 2018 23:14:20 -0500 [thread overview]
Message-ID: <jwv4lo38u2o.fsf-monnier+gmane.emacs.devel@gnu.org> (raw)
In-Reply-To: 83lghlfinq.fsf@gnu.org
>> I bumped into the following code in dired-get-filename:
>>
>> ;; The above `read' will return a unibyte string if FILE
>> ;; contains eight-bit-control/graphic characters.
>> (if (and enable-multibyte-characters
>> (not (multibyte-string-p file)))
>> (setq file (string-to-multibyte file)))
>>
>> and I'm wondering why we don't want a unibyte string here.
>> `vc-region-history` told me this comes from the commit appended below,
>> which seems to indicate that we're worried about a subsequent encoding,
>> but AFAIK unibyte file names are not (re)encoded, and passing them
>> through string-to-multibyte would actually make things worse in this
>> respect (since it might cause the kind of (re)encoding this is
>> supposedly trying to avoid).
>>
>> What am I missing?
>
> Why does it matter whether eight-bit-* characters are encoded one more
> or one less time?
That's part of the question, indeed.
> As for the reason for using string-to-multibyte: maybe it's because we
> use concat further down in the function, which will determine whether
> the result will be unibyte or multibyte according to its own ideas of
> what's TRT?
But `concat` will do a string-to-multibyte for us, if needed, so
that doesn't seem like a good reason.
This said, when that code was written, maybe `concat` used
string-make-multibyte internally instead, so this call to
string-to-multibyte might have been added to avoid using
string-make-multibyte inside `concat`?
It would be good to have a concrete case that needed the above code, to
see if the problem still exists.
Stefan
next prev parent reply other threads:[~2018-01-03 4:14 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-29 14:34 Why does dired go through extra efforts to avoid unibyte names Stefan Monnier
2017-12-29 19:17 ` Eli Zaretskii
2018-01-03 4:14 ` Stefan Monnier [this message]
2018-01-03 15:10 ` Eli Zaretskii
2018-01-03 20:09 ` Stefan Monnier
2018-01-05 9:10 ` Eli Zaretskii
2018-01-05 16:12 ` Stefan Monnier
2018-01-05 18:14 ` Eli Zaretskii
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=jwv4lo38u2o.fsf-monnier+gmane.emacs.devel@gnu.org \
--to=monnier@iro.umontreal.ca \
--cc=emacs-devel@gnu.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this external index
https://git.savannah.gnu.org/cgit/emacs.git
https://git.savannah.gnu.org/cgit/emacs/org-mode.git
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.