220 2720 <510F45EA.1080308@gmail.com> article Path: news.gmane.org!not-for-mail From: =?ISO-8859-1?Q?Mikael_Kilpel=E4inen?= Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: A proposal to add swap traits to the standard library Date: Mon, 04 Feb 2013 06:23:54 +0100 Lines: 41 Approved: news@gmane.org Message-ID: <510F45EA.1080308@gmail.com> References: <1359827596.1381.2.camel@Nokia-N900> <41C25E3D-C254-43AE-BFEA-ED83B7DAF74E@gmail.com> <510E1906.3030604@wanadoo.fr> <91576F12-5D5E-45A5-AFC1-E5A4D80052C8@gmail.com> <510EC81E.6050803@gmail.com> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: quoted-printable X-Trace: ger.gmane.org 1359955446 32168 80.91.229.3 (4 Feb 2013 05:24:06 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Mon, 4 Feb 2013 05:24:06 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBDHYRTPW4EBRB44LXWEAKGQE2B73NMQ@isocpp.org Mon Feb 04 06:24:27 2013 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-wi0-f199.google.com ([209.85.212.199]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1U2EXX-00032f-8V for gclcip-std-proposals@m.gmane.org; Mon, 04 Feb 2013 06:24:23 +0100 Original-Received: by mail-wi0-f199.google.com with SMTP id hq4sf2969404wib.2 for ; Sun, 03 Feb 2013 21:24:04 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=x-received:x-beenthere:x-received:x-received:received-spf :x-received:message-id:date:from:user-agent:mime-version:to:subject :references:in-reply-to:x-original-sender :x-original-authentication-results:reply-to:precedence:mailing-list :list-id:x-google-group-id:list-post:list-help:list-archive :list-subscribe:list-unsubscribe:content-type :content-transfer-encoding; bh=9wajLw/5wP1fEhOHhGH/+91kELpzy0kPJMf03Vp8nFI=; b=dKvbvsI8IUjd+RP54BqCeCbbeI1Esyj3K9+yHF2u7G23/8fdyTiTb6RkF4xImuqniX TGv2d5X63ZZ81Q0Shp2rh4UIXee88Ba6v37RGDtZsa1Rxw5WOR0XyUzVKfwJYngslji5 vEkZpMBnfU2DltUxxcHa57trwoXjgHpkT+FP4pDXzSOYWM01YDigkXmtxJbkiqYDhngX EKaWjD2xoVIUob/7CS1MOwt972wnA1hrvyxPG5G9vZzHBE29l/J+WhDprh8xkD3zl4w+ NQ X-Received: by 10.180.19.132 with SMTP id f4mr1344182wie.2.1359955444516; Sun, 03 Feb 2013 21:24:04 -0800 (PST) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.180.101.165 with SMTP id fh5ls593819wib.13.gmail; Sun, 03 Feb 2013 21:24:02 -0800 (PST) X-Received: by 10.14.198.198 with SMTP id v46mr67885388een.4.1359955441959; Sun, 03 Feb 2013 21:24:01 -0800 (PST) X-Received: by 10.14.198.198 with SMTP id v46mr67885377een.4.1359955441841; Sun, 03 Feb 2013 21:24:01 -0800 (PST) Original-Received: from mail-ea0-f175.google.com (mail-ea0-f175.google.com [209.85.215.175]) by mx.google.com with ESMTPS id g7si26175397eeo.128.2013.02.03.21.24.01 (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Sun, 03 Feb 2013 21:24:01 -0800 (PST) Received-SPF: pass (google.com: domain of mikael.kilpelainen@gmail.com designates 209.85.215.175 as permitted sender) client-ip=209.85.215.175; Original-Received: by mail-ea0-f175.google.com with SMTP id d1so2590127eab.34 for ; Sun, 03 Feb 2013 21:24:01 -0800 (PST) X-Received: by 10.14.221.9 with SMTP id q9mr68279393eep.3.1359955441221; Sun, 03 Feb 2013 21:24:01 -0800 (PST) Original-Received: from [10.10.10.213] (static-87-79-94-26.netcologne.de. [87.79.94.26]) by mx.google.com with ESMTPS id k7sm22697459een.8.2013.02.03.21.24.00 (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Sun, 03 Feb 2013 21:24:00 -0800 (PST) User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:8.0) Gecko/20111105 Thunderbird/8.0 In-Reply-To: <510EC81E.6050803@gmail.com> X-Original-Sender: mikael.kilpelainen@gmail.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of mikael.kilpelainen@gmail.com designates 209.85.215.175 as permitted sender) smtp.mail=mikael.kilpelainen@gmail.com; dkim=pass header.i=@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:2720 Archived-At: 3.2.2013 21:27, Mikael Kilpel=E4inen kirjoitti: > > template > void foo(T&, T&) noexcept(noexcept( std::tuple().swap(=20 > std::declval&>() ))); > > Seems i was already sleeping when i wrote that, as obviously this=20 imposes some restrictions for T but maybe the concept works as a dirty=20 workaround. So lets summarise most of the thread : - Problem exists with free functions and lookup if wanted to use in=20 noexcept, trailing return - Having is_swappable traits (as proposed) fixes it for one of the most=20 common cases, and i do agree it feels like those type traits are missing. - We might be able to fix this for most std free functions by making=20 them first to perform ADL like pointed out by Yasskin. I wonder how many=20 swap relies on calling the std::swap directly though and possibly=20 recursing then. The problem itself it generic, but is it worth "fixing"? Is there much=20 similar usage with other than std library that would benefit from it? Mikael --=20 ---=20 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 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-proposa= ls/?hl=3Den. .