From 5310082004608486487 X-Google-Thread: f78e5,bd52daa8ac2e51f1 X-Google-Thread: 109fba,bd52daa8ac2e51f1 X-Google-Attributes: gidf78e5,gid109fba,public,usenet X-Google-Language: ENGLISH,ASCII-7-bit Path: g2news2.google.com!news1.google.com!news.glorb.com!news.alt.net!comp-std-cpp-robomod!not-for-mail From: int19h@gmail.com Newsgroups: comp.std.c++,comp.lang.c++ Subject: Re: pre return optimization Date: Wed, 17 Oct 2007 11:53:54 CST Organization: http://groups.google.com Lines: 19 Approved: Fergus Henderson , moderator of comp.std.c++ Message-ID: <1192594314.094118.106830@q5g2000prf.googlegroups.com> References: <1191919832.635392.256930@d55g2000hsg.googlegroups.com> <1192280210.586133.256780@e34g2000pro.googlegroups.com> <1192533980.713544.27090@e34g2000pro.googlegroups.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" X-Trace: posting.google.com 1192594314 26743 127.0.0.1 (17 Oct 2007 04:11:54 GMT) X-Complaints-To: groups-abuse@google.com NNTP-Posting-Date: Wed, 17 Oct 2007 04:11:54 +0000 (UTC) Return-Path: X-Authentication-Warning: mulga.csse.unimelb.edu.au: fjh set sender to devnull@stump.algebra.com using -f X-Robomod: STUMP, ichudov@algebra.com (Igor Chudov) X-Original-To: std-c++@mailman.ucar.edu Delivered-To: std-c++@mailman.ucar.edu X-SMTP-Auth: no User-Agent: G2/1.0 X-HTTP-UserAgent: Opera/9.22 (Windows NT 5.1; U; en),gzip(gfe),gzip(gfe) Complaints-To: groups-abuse@google.com Injection-Info: q5g2000prf.googlegroups.com; posting-host=85.140.22.182; posting-account=ps2QrAMAAAA6_jCuRt2JEIpn5Otqf_w0 X-Virus-Scanned: amavisd-new at ucar.edu X-Virus-Scanned: amavisd-new at csse.unimelb.edu.au X-Virus-Scanned: amavisd-new at csse.unimelb.edu.au Xref: g2news2.google.com comp.std.c++:868 comp.lang.c++:22973 On 16 Oct, 23:26, "terminator(jam)" wrote: > A foo(){ > A ret;//this will be return under any conditions. > //.... > return ret;//pre return :no copy/move}; > > class A a=foo();//after return : copy/move to a This is not the case. If the compiler correctly implements NRVO, the example above will result in a single construction of A using the default constructor, and then a subsequent destruction. No copies or moves are made at any point. --- [ comp.std.c++ is moderated. To submit articles, try just posting with ] [ your news-reader. If that fails, use mailto:std-c++@ncar.ucar.edu ] [ --- Please see the FAQ before posting. --- ] [ FAQ: http://www.comeaucomputing.com/csc/faq.html ]