220 10908 <6A35DB23-8AAC-49C4-9A52-0BB194D38E01@gmail.com> article Path: news.gmane.org!not-for-mail From: David Krauss Newsgroups: gmane.comp.lang.c++.isocpp.proposals Subject: Re: Re: N4009: return type of erase_if Date: Wed, 28 May 2014 10:17:19 +0800 Lines: 38 Approved: news@gmane.org Message-ID: <6A35DB23-8AAC-49C4-9A52-0BB194D38E01@gmail.com> References: <09b01713-0312-495e-b984-f492307f0f47@isocpp.org> <80B2AD70-C23C-474D-88E9-24B7EA7EE545@gmail.com> <799E7B56-C6B1-4223-84AE-D6BCE0A99FE8@gmail.com> Reply-To: std-proposals@isocpp.org NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 (Mac OS X Mail 7.3 \(1878.2\)) Content-Type: text/plain; charset=ISO-8859-1 X-Trace: ger.gmane.org 1401243453 28992 80.91.229.3 (28 May 2014 02:17:33 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Wed, 28 May 2014 02:17:33 +0000 (UTC) To: std-proposals@isocpp.org Original-X-From: std-proposals+bncBCW25A7E3QCRBNEOSWOAKGQEOSYNU4Q@isocpp.org Wed May 28 04:17:26 2014 Return-path: Envelope-to: gclcip-std-proposals@m.gmane.org Original-Received: from mail-qg0-f72.google.com ([209.85.192.72]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1WpTQk-0001w7-Al for gclcip-std-proposals@m.gmane.org; Wed, 28 May 2014 04:17:26 +0200 Original-Received: by mail-qg0-f72.google.com with SMTP id q108sf24800812qgd.3 for ; Tue, 27 May 2014 19:17:25 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:subject:from:in-reply-to:date :message-id:references:to:x-original-sender :x-original-authentication-results:reply-to:precedence:mailing-list :list-id:list-post:list-help:list-archive:list-subscribe :list-unsubscribe:content-type; bh=aUskNCMbvah86Si07iNNagMq+js0wJ91IRnvgaW9Be0=; b=IjbH+HAHn3OgG/08SprpSB9L7R733mgh3wczokgQkdoyDUegHfD49/BQp9G2zxnOf4 CfX7YEJnUWAkLRBkeUt/iCKBkFLkFMdD96kSrJ/LJS5UR/FokdLLU4weWtWAPZDqtea7 GzlexdgANTlQVX/7QgSmNy24dRXeosQlbNDbpcbDQhORS84TnzJpGCiffaiNrmKqOHqv uERxkxg9OuNG99ebWJy+N2xRTn+5iKSFFbMwCVFJGmNwIPz/hB/gTIyROdiYpvAmWsK7 urkGdzG6aeHeYhcP2UsA2gbr+v3sIGoDVM0U25zyVVIZ4T6wlsmz8vKaCk9WRdjrB+mG /nOQ== X-Gm-Message-State: ALoCoQnOLD+utAUeZzTaYFpT55i6P+ADalH7QM4WkeC9s5ePKsUNpvpZs5Ef0FVr80rLesnEGCFQ X-Received: by 10.58.106.75 with SMTP id gs11mr14925071veb.18.1401243445201; Tue, 27 May 2014 19:17:25 -0700 (PDT) X-BeenThere: std-proposals@isocpp.org Original-Received: by 10.50.79.135 with SMTP id j7ls2476723igx.20.gmail; Tue, 27 May 2014 19:17:24 -0700 (PDT) X-Received: by 10.43.138.8 with SMTP id iq8mr33694469icc.37.1401243444397; Tue, 27 May 2014 19:17:24 -0700 (PDT) Original-Received: from mail-ie0-x233.google.com (mail-ie0-x233.google.com [2607:f8b0:4001:c03::233]) by mx.google.com with ESMTPS id t8si29930235icf.77.2014.05.27.19.17.24 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Tue, 27 May 2014 19:17:24 -0700 (PDT) Received-SPF: pass (google.com: domain of potswa@gmail.com designates 2607:f8b0:4001:c03::233 as permitted sender) client-ip=2607:f8b0:4001:c03::233; Original-Received: by mail-ie0-f179.google.com with SMTP id rd18so9692140iec.38 for ; Tue, 27 May 2014 19:17:24 -0700 (PDT) X-Received: by 10.50.114.34 with SMTP id jd2mr31767366igb.35.1401243444168; Tue, 27 May 2014 19:17:24 -0700 (PDT) Original-Received: from [172.20.10.2] ([121.54.54.60]) by mx.google.com with ESMTPSA id om5sm12173695igb.16.2014.05.27.19.17.22 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Tue, 27 May 2014 19:17:23 -0700 (PDT) In-Reply-To: X-Mailer: Apple Mail (2.1878.2) X-Original-Sender: potswa@gmail.com X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of potswa@gmail.com designates 2607:f8b0:4001:c03::233 as permitted sender) smtp.mail=potswa@gmail.com; dkim=pass header.i=@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-Google-Group-Id: 399137483710 List-Post: , List-Help: , List-Archive: List-Subscribe: , List-Unsubscribe: , Xref: news.gmane.org gmane.comp.lang.c++.isocpp.proposals:10908 Archived-At: On 2014-05-28, at 12:44 AM, Matthew Woehlke wrote: > On 2014-05-27 08:45, David Krauss wrote: >> On 2014-05-27, at 7:14 PM, vadim.petrochenkov@gmail.com wrote: >>> I'm curious, is there any general policy in the library on changing >>> or not changing "return void" to something in any way useful? >>> >>> Because assuming the statement If the result is discarded, the >>> compiler will be able to elide its computation after inlining. is >>> true, a lot of member functions, for example, could potentially >>> benefit from returning *this instead of void, but they still return >>> void for some reason. >> >> Returning this (or *this) is of no help to the CPU, which already has >> access to the value from wherever it got it prior to the call. > > I suspect the benefit here isn't optimization, but rather code writing, > e.g. to be able to write: There was probably some misunderstanding about what I meant by "elide computation." > std::vector v; > v.clear().push_back(2).insert(v.begin(), 1); // etc. > > (Not the best example, but hopefully you get the idea.) As good an example as any. That's not the direction of C++. A carriage return and a variable declaration never killed anyone. -- --- 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/. .