220 4442 <6f1d5998-83c2-46f5-ba60-0841a278e424@isocpp.org> article Path: news.gmane.org!not-for-mail From: Nicol Bolas Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: std::putf now supports %N%, like Boost.Format Date: Wed, 15 May 2013 23:16:51 -0700 (PDT) Lines: 85 Approved: news@gmane.org Message-ID: <6f1d5998-83c2-46f5-ba60-0841a278e424@isocpp.org> References: <66ac5a48-8d1a-41f3-92ac-085c3b7de87a@isocpp.org> <75cd8f0a-81be-40d5-84a5-69287b3b18e2@isocpp.org> <8a59c705-90ba-4e45-b9f8-4b0556e16032@isocpp.org> <2f4ea651-e0a4-4427-9e32-73a23c3a3e8a@isocpp.org> <83caa602-33d7-491a-9620-5ab7711fb054@isocpp.org> <58823f67-4fa4-4fda-9a3b-452c32bfee27@isocpp.org> <671ee342-ad52-4a4c-8dda-847a61babc7b@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_Part_389_14437684.1368685011305" X-Trace: ger.gmane.org 1368685017 29708 80.91.229.3 (16 May 2013 06:16:57 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Thu, 16 May 2013 06:16:57 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCEKFTV6ZUMBBVPT2GGAKGQEEG3EP7Y@isocpp.org Thu May 16 08:16:58 2013 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-ob0-f198.google.com ([209.85.214.198]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1UcrUm-0002FB-0m for gclcip-std-proposals@m.gmane.org; Thu, 16 May 2013 08:16:56 +0200 Original-Received: by mail-ob0-f198.google.com with SMTP id er7sf9959648obc.5 for ; Wed, 15 May 2013 23:16:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=x-received:x-beenthere:x-received:date:from:to:message-id :in-reply-to:references:subject:mime-version:x-original-sender :reply-to:precedence:mailing-list:list-id:x-google-group-id :list-post:list-help:list-archive:list-subscribe:list-unsubscribe :content-type; bh=YDW/9llC2MA3yhmr54eeigkddIHE0TuECq5P4RcnWrs=; b=SAyMUm3hMlVbZ4C3xUtQTGN3z7CFB1fBDU6Qbui9nwFwW7uHSgx36BSJN9I8/VJXAk 1fMqij/d7QqbEILOhIud/8mG85+1Ngit4DutuQLkZR8JO+1M3Do4pZLhWrNc2Yjiy5OR Xj1TmRxY+J9Q5nIrNyt1i9fDrqyrRxv78DCQ9i7jqQh0ETiPeIxvsQOiwu6H/NM7Wz4O oGbRcuzCZVVjCk059ZsUi0sk/i74oO5D9RGQkwDD+Yl7+KpL8UjBc0R/MeXRszZJBEuF zg/1Unqg3EOglnG/yAjwpwYEjUtCToa8g6M8wXGHDrxEaFs8KEg3LvGIQF7zDcY/bk0g RW6g== X-Received: by 10.50.50.33 with SMTP id z1mr5901616ign.6.1368685014865; Wed, 15 May 2013 23:16:54 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.50.36.10 with SMTP id m10ls1927957igj.24.gmail; Wed, 15 May 2013 23:16:52 -0700 (PDT) X-Received: by 10.50.196.227 with SMTP id ip3mr1785034igc.10.1368685012522; Wed, 15 May 2013 23:16:52 -0700 (PDT) In-Reply-To: X-Original-Sender: jmckesson@gmail.com Precedence: list Mailing-list: list std-proposals@isocpp.org; contact std-proposals+owners@isocpp.org List-ID: X-Google-Group-Id: 399137483710 List-Post: , List-Help: , List-Archive: List-Subscribe: , List-Unsubscribe: , Xref: news.gmane.org gmane.comp.lang.c++.isocpp.proposals:4442 Archived-At: ------=_Part_389_14437684.1368685011305 Content-Type: text/plain; charset=ISO-8859-1 On Wednesday, May 15, 2013 9:54:14 PM UTC-7, Zhihao Yuan wrote: > > On Wed, May 15, 2013 at 11:08 PM, Nicol Bolas > > wrote: > > That is, if you provided a > > standard-conforming printf format to putf, it would work as expected. If > you > > don't, then you get undefined behavior from putf. > > Errr, not quite. `putf` has no undefined behavior. Everything not being > well > defined in `printf` results in a less feature complete (from the point > of view of > C-printf, but not iomanip) output, or a failbit on the stream. I consider > any > thing not well-defined in `putf` as a bug (it makes no sense to have UB > in a string formatting facility, seriously). > OK, I said that wrong, so let me rephrase. If you have a standard-conforming printf formatting string, then `putf` will accept it and do the same thing. If your format string wasn't standard-conforming, then there's no guarantee of what printf will do. So `putf` doesn't need to accept it. -- --- You received this message because you are subscribed to the Google Groups "ISO C++ Standard - Future Proposals" group. To unsubscribe from this group and stop receiving emails from it, send an email to std-proposals+unsubscribe@isocpp.org. To post to this group, send email to std-proposals@isocpp.org. Visit this group at http://groups.google.com/a/isocpp.org/group/std-proposals/?hl=en. ------=_Part_389_14437684.1368685011305 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable On Wednesday, May 15, 2013 9:54:14 PM UTC-7, Zhihao Yuan wrote:
On Wed, May 15, 2013 at 11:08 PM, Nicol Bo= las <jmck...@gmail.com> wrote:
> That is, if you provided a
> standard-conforming printf format to putf, it would work as expect= ed. If you
> don't, then you get undefined behavior from putf.

Errr, not quite.  `putf` has no undefined behavior.  Everythi= ng not being well
defined in `printf` results in a less feature complete (from the point
of view of
C-printf, but not iomanip) output, or a failbit on the stream.  I = consider any
thing not well-defined in `putf` as a bug (it makes no sense to have UB
in a string formatting facility, seriously).

OK, I said that wrong, so let me rephrase.
If you have a standard-conforming printf formatting string, then `putf` wi= ll accept it and do the same thing. If your format string wasn't standard-c= onforming, then there's no guarantee of what printf will do. So `putf` does= n't need to accept it.

--
 
---
You received this message because you are subscribed to the Google Groups &= quot;ISO C++ Standard - Future Proposals" group.
To unsubscribe from this group and stop receiving emails from it, send an e= mail to std-proposals+unsubscribe@isocpp.org.
To post to this group, send email to std-proposals@isocpp.org.
Visit this group at http://groups.google.com/a/isocpp.org/group/std-pro= posals/?hl=3Den.
 
 
------=_Part_389_14437684.1368685011305-- .