220 5231 article Path: news.gmane.org!not-for-mail From: Ville Voutilainen Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: Teachability problems with std::move Date: Wed, 26 Jun 2013 14:23:41 +0300 Lines: 80 Approved: news@gmane.org Message-ID: References: <73cad38f-c1b6-4ce3-bfc1-e4a660dbb638@isocpp.org> <09ec0612-ac10-48fb-a186-bd3c200bd5fe@isocpp.org> <20f56505-2fba-4041-9d81-26088e67dc5d@isocpp.org> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary=001a1132eceec2610e04e00ce00a X-Trace: ger.gmane.org 1372245823 26257 80.91.229.3 (26 Jun 2013 11:23:43 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 26 Jun 2013 11:23:43 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBC5JHI7A7ALRBPU6VOHAKGQENUI7A2A@isocpp.org Wed Jun 26 13:23:45 2013 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-yh0-f69.google.com ([209.85.213.69]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1Urnp9-0003ec-T4 for gclcip-std-proposals@m.gmane.org; Wed, 26 Jun 2013 13:23:44 +0200 Original-Received: by mail-yh0-f69.google.com with SMTP id b12sf19506493yha.8 for ; Wed, 26 Jun 2013 04:23:43 -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=xz2iM3xt1RApKP6onRlMrWqOpomo1CVI/MtNsU6/SJk=; b=XcdY6YHP0WtOG5GQATFqZ4d8LVNsioXw92iBPC9WzsOFz9jbEEIex8hu9CKIIOJdOl utPoueG/yeOhWIW07j6qKUnIAjovL5KWO3OumTAkZfGgzi6HS4DaxuT1oyaR4KeG2SLY yw5WJYvNf2/+sqDXrmmfIBQL+2mROVYXegK8SpwCibgiGaJsyUuQ8ITiht6T09/BGkXj pe9zQU1YXSPiol/AS2rjBbIFz8vCLlMSSLpSiC7BS91FlC9PPP3ddMU4e2dxd1cEbqIN 430+GePQKKnrVBMm9yfwKRbUrzkOGBVgkUmPbkhkcOBO7nVmcg1NkbwvXELmvv5Vebs2 qNiQ== X-Received: by 10.236.79.67 with SMTP id h43mr1864851yhe.46.1372245822967; Wed, 26 Jun 2013 04:23:42 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.49.107.129 with SMTP id hc1ls352969qeb.78.gmail; Wed, 26 Jun 2013 04:23:42 -0700 (PDT) X-Received: by 10.224.26.7 with SMTP id b7mr4629373qac.102.1372245822095; Wed, 26 Jun 2013 04:23:42 -0700 (PDT) Original-Received: from mail-qc0-x230.google.com (mail-qc0-x230.google.com [2607:f8b0:400d:c01::230]) by mx.google.com with ESMTPS id t4si6057762qap.134.2013.06.26.04.23.42 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Wed, 26 Jun 2013 04:23:42 -0700 (PDT) Received-SPF: pass (google.com: domain of ville.voutilainen@gmail.com designates 2607:f8b0:400d:c01::230 as permitted sender) client-ip=2607:f8b0:400d:c01::230; Original-Received: by mail-qc0-f176.google.com with SMTP id z10so8104488qcx.35 for ; Wed, 26 Jun 2013 04:23:42 -0700 (PDT) X-Received: by 10.229.174.70 with SMTP id s6mr899702qcz.104.1372245821905; Wed, 26 Jun 2013 04:23:41 -0700 (PDT) Original-Received: by 10.224.174.143 with HTTP; Wed, 26 Jun 2013 04:23:41 -0700 (PDT) In-Reply-To: X-Original-Sender: ville.voutilainen@gmail.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of ville.voutilainen@gmail.com designates 2607:f8b0:400d:c01::230 as permitted sender) smtp.mail=ville.voutilainen@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:5231 Archived-At: --001a1132eceec2610e04e00ce00a Content-Type: text/plain; charset=ISO-8859-1 On 26 June 2013 14:10, Mikhail Semenov wrote: > > Coming back to the original topic, are you really suggesting the code > above is the ideal form for teaching when to use std::move and when > not > to? I think "return result;" is much simpler. > > If you have to convert from std::unique_ptr to std::unique_ptr Foo> > the following code *WON'T COMPILE*; > *return result;* > > *Try it in your compiler!* > We know. There's no need to shout. The whole question is whether it should be valid, aka compile. The conversion in this case is perfectly safe, so perhaps we should consider relaxing the rules. -- --- 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/. --001a1132eceec2610e04e00ce00a Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable



On 26 June 2013 14:10, Mikhail Semenov <mikhailsemenov1= 957@gmail.com> wrote:
> Coming back to the original topic, are you really suggesting = the code above is the ideal form for teaching when to use std::move and whe= n > not to?=A0 I think "return result;" is much simpler.
= =A0
If you hav= e to convert from std::unique_ptr<Foo> to std::unique_ptr<const Fo= o>
the following code WON'T COMPILE;
return result;
=A0
Try it in your compiler!

We know. There's no need to shout. The w= hole question is whether it should be valid, aka compile.
The conversion in this case is perfectly safe, so perhaps we should conside= r relaxing the rules.

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