From: Paul Eggert <eggert@cs.ucla.edu>
To: Dmitry Antipov <dmantipov@yandex.ru>
Cc: Eli Zaretskii <eliz@gnu.org>,
emacs-devel@gnu.org, stephen@xemacs.org,
monnier@iro.umontreal.ca
Subject: Re: ptrdiff_t misuse
Date: Fri, 06 Jul 2012 10:39:15 -0700 [thread overview]
Message-ID: <4FF722C3.9070104@cs.ucla.edu> (raw)
In-Reply-To: <4FF71574.5000207@yandex.ru>
On 07/06/2012 09:42 AM, Dmitry Antipov wrote:
> I read ptrdiff_t exactly as "difference between pointers", and this is
> the minor drawback; the major one is that there is no standard unsigned
> counterpart, like for size_t/ssize_t pair.
For buffer positions and the like, Emacs code can take size_t to be
the unsigned counterpart of ptrdiff_t. For Emacs we typically prefer
signed integers, so the need for size_t is rare -- in fact some of the
current uses of size_t should be changed to ptrdiff_t, for consistency
with the usual Emacs style.
There are hosts with size_t wider than ssize_t (POSIX allows this).
That is why we use ptrdiff_t, not ssize_t, for buffer positions and
the like -- on those hosts, ssize_t wouldn't work for large buffers.
Conversely, on some (rare) hosts ptrdiff_t is wider than size_t (POSIX
allows this too). As far as I know Emacs has never been ported to
these hosts but it should work, since buffer positions will fit into
ptrdiff_t.
next prev parent reply other threads:[~2012-07-06 17:39 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-29 13:20 (unknown) Eli Zaretskii
2012-06-29 14:18 ` ptrdiff_t misuse [was :Re: (empty)] Dmitry Antipov
2012-06-29 17:07 ` Stefan Monnier
2012-06-30 7:13 ` Paul Eggert
2012-06-30 7:27 ` Eli Zaretskii
2012-06-30 13:12 ` Paul Eggert
2012-06-30 14:23 ` Stefan Monnier
2012-06-30 12:07 ` Stefan Monnier
2012-06-30 13:14 ` Paul Eggert
2012-06-30 14:23 ` Stefan Monnier
2012-07-04 6:25 ` Paul Eggert
2012-07-04 16:39 ` Eli Zaretskii
2012-07-04 18:19 ` Paul Eggert
2012-07-05 16:31 ` Eli Zaretskii
2012-07-05 19:34 ` Eli Zaretskii
2012-07-06 0:08 ` Paul Eggert
2012-07-06 6:43 ` Eli Zaretskii
2012-07-06 7:32 ` Paul Eggert
2012-07-06 8:34 ` ptrdiff_t misuse Eli Zaretskii
2012-07-06 14:51 ` Paul Eggert
2012-07-06 21:30 ` Stefan Monnier
2012-07-06 21:33 ` Samuel Bronson
2012-07-07 10:59 ` Stefan Monnier
2012-07-07 15:34 ` Paul Eggert
2012-07-06 8:46 ` Eli Zaretskii
2012-07-06 10:19 ` Stephen J. Turnbull
2012-07-06 11:01 ` Eli Zaretskii
2012-07-06 12:02 ` Stephen J. Turnbull
2012-07-06 13:37 ` Eli Zaretskii
2012-07-06 16:25 ` Stephen J. Turnbull
2012-07-06 14:56 ` Paul Eggert
2012-07-06 15:43 ` Eli Zaretskii
2012-07-06 15:56 ` Paul Eggert
2012-07-06 16:00 ` Eli Zaretskii
2012-07-06 16:42 ` Dmitry Antipov
2012-07-06 17:39 ` Paul Eggert [this message]
2012-07-07 1:31 ` Chong Yidong
2012-06-29 18:54 ` ptrdiff_t misuse [was :Re: (empty)] 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
List information: https://www.gnu.org/software/emacs/
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=4FF722C3.9070104@cs.ucla.edu \
--to=eggert@cs.ucla.edu \
--cc=dmantipov@yandex.ru \
--cc=eliz@gnu.org \
--cc=emacs-devel@gnu.org \
--cc=monnier@iro.umontreal.ca \
--cc=stephen@xemacs.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 public inbox
https://git.savannah.gnu.org/cgit/emacs.git
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).