220 4860 article Path: news.gmane.org!not-for-mail From: =?ISO-8859-1?Q?Daniel_Kr=FCgler?= Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: Proposal: std::sequence Date: Tue, 4 Jun 2013 22:21:19 +0200 Lines: 40 Approved: news@gmane.org Message-ID: References: <4551abbc-43aa-4520-a91a-f8eb25a90588@isocpp.org> <2c8e6079-9c87-425a-93e2-39251df57cd8@isocpp.org> <9f1cace3-0503-4a3c-a8ce-d7546564b3ef@isocpp.org> <1c991e6e-6bc3-4822-9ffd-7f2508e63974@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 X-Trace: ger.gmane.org 1370377282 8508 80.91.229.3 (4 Jun 2013 20:21:22 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Tue, 4 Jun 2013 20:21:22 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCT7RVFA4QORBQMYXGGQKGQEIIAVGTY@isocpp.org Tue Jun 04 22:21:23 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 1UjxjO-0002HQ-Ab for gclcip-std-proposals@m.gmane.org; Tue, 04 Jun 2013 22:21:22 +0200 Original-Received: by mail-wi0-f199.google.com with SMTP id hi5sf645768wib.6 for ; Tue, 04 Jun 2013 13:21:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=x-beenthere:mime-version:in-reply-to:references:date:message-id :subject:from: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; bh=gXPCT4OrooR4vN+PTkRbonJR8rHrM0Sh3ifz02Gsvas=; b=SfrLTztra0jokaTMf/pGIJGNbb2OpIAQ2autowOgBuxalpcaaUS5aL9EfT6FvMaTUm z1F1IktvBuWPEF47UfSxSvKB+8hpEPy3K4/n85vQjT8fT41p5VQpIrtl6ej9PEKipMyd nNNI8Z6UBMFqeTwaumCdXByGAHX2TnRKGiSJyvcPBBbhESNY8SxuNJzZo76YR0Bey9VN xOU2QaxfpKWUrn6efuOTfz+EAsfC8C3LypEWq22jaYbuNPQmfsWZR64jtuvWcFRYo4Fv 64HXP2TniK0oW9YV4w1MTVQXWxxGtzZtmsX205Gr9m2rduRjy2EdAgIvCogzU7IMtnxr 4eNg== X-Received: by 10.180.185.115 with SMTP id fb19mr1383244wic.0.1370377281825; Tue, 04 Jun 2013 13:21:21 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.180.13.16 with SMTP id d16ls1367141wic.37.canary; Tue, 04 Jun 2013 13:21:19 -0700 (PDT) X-Received: by 10.180.81.169 with SMTP id b9mr3320032wiy.12.1370377279807; Tue, 04 Jun 2013 13:21:19 -0700 (PDT) Original-Received: from mail-wg0-x22f.google.com (mail-wg0-x22f.google.com [2a00:1450:400c:c00::22f]) by mx.google.com with ESMTPS id n8si2518063wiy.57.2013.06.04.13.21.19 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Tue, 04 Jun 2013 13:21:19 -0700 (PDT) Received-SPF: pass (google.com: domain of daniel.kruegler@gmail.com designates 2a00:1450:400c:c00::22f as permitted sender) client-ip=2a00:1450:400c:c00::22f; Original-Received: by mail-wg0-f47.google.com with SMTP id e11so639527wgh.14 for ; Tue, 04 Jun 2013 13:21:19 -0700 (PDT) X-Received: by 10.180.90.70 with SMTP id bu6mr3208851wib.34.1370377279710; Tue, 04 Jun 2013 13:21:19 -0700 (PDT) Original-Received: by 10.216.164.10 with HTTP; Tue, 4 Jun 2013 13:21:19 -0700 (PDT) In-Reply-To: X-Original-Sender: daniel.kruegler@gmail.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of daniel.kruegler@gmail.com designates 2a00:1450:400c:c00::22f as permitted sender) smtp.mail=daniel.kruegler@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:4860 Archived-At: 2013/6/4 Jeffrey Yasskin : > On Tue, Jun 4, 2013 at 12:03 PM, Nevin Liber wrote: >> On 4 June 2013 13:54, Jeffrey Yasskin wrote: >>> >>> >>> Please don't say "clearly" here. Assignability is the default in C++, >>> and it's quite possible that our implementations stumbled into it >>> without actually having a firm use case. It would take actual research >>> to determine that we have a real need. (I suspect we do, but my >>> suspicion doesn't prove anything, and I'm not currently planning to >>> investigate in detail.) >> >> >> Other than dynarray, is there any class in the standard that is copyable but >> not assignable? > > I don't think so. I agree with Jeffrey. In C++03 std::valarray was not assignable in the absolute sense: If both operands had different sizes, the behaviour was undefined. But we changed this for C++11. I'm not convinced that dynarray is comparable to valarray enough to argue in favour for allowing assignments based on this data point, though. It looks like a potential option for the future, but I really would like to see practical experience with dynarray first, especially whether existing implementations will show that allowing relaxing the current assignment constraint would be harmless or not. - 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. Visit this group at http://groups.google.com/a/isocpp.org/group/std-proposals/?hl=en. .