220 26362 article Path: news.gmane.org!not-for-mail From: =?UTF-8?Q?Daniel_Kr=C3=BCgler?= Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Swapping with volatile lvalues Date: Tue, 21 Jun 2016 09:49:54 +0200 Lines: 26 Approved: news@gmane.org Message-ID: References: <81998cb5-722e-49a1-be98-7ca1e219b72a@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-Trace: ger.gmane.org 1466495402 28439 80.91.229.3 (21 Jun 2016 07:50:02 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Tue, 21 Jun 2016 07:50:02 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCT7RVFA4QORBJHDUO5QKGQEFI62RYA@isocpp.org Tue Jun 21 09:49:58 2016 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-lf0-f72.google.com ([209.85.215.72]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1bFGRa-0003d0-5y for gclcip-std-proposals@m.gmane.org; Tue, 21 Jun 2016 09:49:58 +0200 Original-Received: by mail-lf0-f72.google.com with SMTP id a4sf5477936lfa.1 for ; Tue, 21 Jun 2016 00:49:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=isocpp-org.20150623.gappssmtp.com; s=20150623; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :x-original-sender:x-original-authentication-results:reply-to :precedence:mailing-list:list-id:x-spam-checked-in-group:list-post :list-help:list-archive:list-subscribe:list-unsubscribe; bh=BIuK0DIKW9rxdfKTAADUnpn7M274pJdXG7ZJElB1u5s=; b=bZsmHJ20Hg3izFhlWyaUFEAcS8aiPQikrdmxSgbFWGQ+GvpslyCW7uLvsPbwZouVBp 9HShs++loxWBBAlMpKTYNwquENhQjGygn0QpK1DGGASROG3T44/DncjndYyKQ/zQ7aTn uuV+0j4hyFmibv4KmsBfv4+ttI+uJgH/hII51iFz9iT/mb8yalsAmLifVfinaKQZA8Fp id0XcVHotGAj4hlT8gpIOBK85zYw372CGC7mTqaQ9X/rKfcykbzvXjyTDB0I1Bd/Fx4E GUm6Qku7/M71yyVbtQxWqJ7eftQ1GrnzF3HtLl0C1eKQMVDYiFyT7fSteXzXKMUivUoI E6JQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:x-original-sender :x-original-authentication-results:reply-to:precedence:mailing-list :list-id:x-spam-checked-in-group:list-post:list-help:list-archive :list-subscribe:list-unsubscribe; bh=BIuK0DIKW9rxdfKTAADUnpn7M274pJdXG7ZJElB1u5s=; b=XWC3A6VGAAArgbhV3GJIGKLIXc/7gL4UG5mjgtdTAnmZRElPIdJdS5bHBSolrz7elt Wm/LR+AkXH7AZUhSP5Pi/D5DmMxpeycJpFWL3YNYPVx9jmVet0DNWAK+fqJW+N0P7qFw bqhGrjuQUl8APGh6VW+B8jTH5yMg3hAVoQNGYdykN/KNKUEqr3ctdj17JyxlpvYDxD6d 3z+STSkwaYv0Lgh/+3P2huvy2lUw5zAL+LcRsA96q1OTRS8mFBDTqRJjqG0isbFRB6R6 BzvukFDEFjgT96U55kLY+XVG1ucmEAnGYexFK1nFiqEGBeAww7dMb3Z78F+aFIye8a3p QncQ== X-Gm-Message-State: ALyK8tKI/6I+xG9T0E3o2M+7Y9FiRk/eaPf4wFMnR7eq9pBqsXPUALIB121cg5goI9xU3g== X-Received: by 10.28.166.73 with SMTP id p70mr291697wme.0.1466495397567; Tue, 21 Jun 2016 00:49:57 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.25.18.84 with SMTP id h81ls133639lfi.23.gmail; Tue, 21 Jun 2016 00:49:55 -0700 (PDT) X-Received: by 10.25.207.5 with SMTP id f5mr5950817lfg.45.1466495395959; Tue, 21 Jun 2016 00:49:55 -0700 (PDT) Original-Received: from mail-lb0-x236.google.com (mail-lb0-x236.google.com. [2a00:1450:4010:c04::236]) by mx.google.com with ESMTPS id g77si28777395lfi.3.2016.06.21.00.49.55 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 21 Jun 2016 00:49:55 -0700 (PDT) Received-SPF: pass (google.com: domain of daniel.kruegler@gmail.com designates 2a00:1450:4010:c04::236 as permitted sender) client-ip=2a00:1450:4010:c04::236; Original-Received: by mail-lb0-x236.google.com with SMTP id xp5so4893319lbb.0 for ; Tue, 21 Jun 2016 00:49:55 -0700 (PDT) X-Received: by 10.195.10.131 with SMTP id ea3mr17338779wjd.86.1466495395416; Tue, 21 Jun 2016 00:49:55 -0700 (PDT) Original-Received: by 10.28.168.148 with HTTP; Tue, 21 Jun 2016 00:49:54 -0700 (PDT) In-Reply-To: <81998cb5-722e-49a1-be98-7ca1e219b72a@isocpp.org> X-Original-Sender: daniel.kruegler@gmail.com X-Original-Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com; spf=pass (google.com: domain of daniel.kruegler@gmail.com designates 2a00:1450:4010:c04::236 as permitted sender) smtp.mailfrom=daniel.kruegler@gmail.com; dmarc=pass (p=NONE dis=NONE) header.from=gmail.com Precedence: list Mailing-list: list std-proposals@isocpp.org; contact std-proposals+owners@isocpp.org List-ID: X-Spam-Checked-In-Group: std-proposals@isocpp.org 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:26362 Archived-At: 2016-06-21 9:29 GMT+02:00 FrankHB1989 : > I find swapping between the non-volatile and volatile lvalues may be useful, > e.g. to save/restore errno where it has volatile type. Though it is easy to > roll my own wheels, is it being considered in the standard, e.g. > `templatevoid swap(T, volatile&) noexcept`? The way you suggest to provide this (asymmetric) signature, to me that doesn't seem to be a function that should be named swap and should be considered during overload resolution of swap functions in the library as described in [swappable.requirements]. For example, note that according to the Swappable requirements, there exist a bunch of requirements regarding symmetry of call expressions and post-conditions, that don't seem to apply here. I have not looked deeper into this, but isn't your suggestion more indicated to be a variant of std::exchange? But even here I'm not 100% sure that this picture fits. - Daniel -- 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. To view this discussion on the web visit https://groups.google.com/a/isocpp.org/d/msgid/std-proposals/CAGNvRgB9K2W%3DAL5y3b7PbVvitDAaTOLXSYzi9rbC2kpZVG%2BZKQ%40mail.gmail.com. .