From -4314035762965560284 X-Google-Thread: f78e5,51456c3eb8f9490e X-Google-Attributes: gidf78e5,public X-Google-Language: ENGLISH,ASCII-7-bit Path: g2news2.google.com!news1.google.com!news.maxwell.syr.edu!news.alt.net!comp-std-cpp-robomod!not-for-mail From: "mark" Newsgroups: comp.std.c++ Subject: Re: Copy Constructor Confusion! Date: Thu, 17 Aug 2006 11:28:31 CST Organization: http://groups.google.com Lines: 54 Approved: Fergus Henderson , moderator of comp.std.c++ Message-ID: <1155753523.459377.147180@m79g2000cwm.googlegroups.com> References: <1155645873.296811.3890@74g2000cwt.googlegroups.com> <1155663179.843769.44420@b28g2000cwb.googlegroups.com> <4kh3o8Fc528lU1@individual.net> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" X-Trace: posting.google.com 1155753528 12427 127.0.0.1 (16 Aug 2006 18:38:48 GMT) X-Complaints-To: groups-abuse@google.com NNTP-Posting-Date: Wed, 16 Aug 2006 18:38:48 +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 User-Agent: G2/0.2 X-HTTP-UserAgent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.0.6) Gecko/20060728 Firefox/1.5.0.6,gzip(gfe),gzip(gfe) Complaints-To: groups-abuse@google.com Injection-Info: m79g2000cwm.googlegroups.com; posting-host=207.135.74.34; posting-account=kmJZpwwAAADTaEqNJ8z_rfhCwbaAxYpY X-Greylisting: NO DELAY (Relay+Sender autoqualified); processed by UCSD_GL-v2.1 on mailbox8.ucsd.edu; Wed, 16 August 2006 11:38:49 -0700 (PDT) X-Spamscanner: mailbox8.ucsd.edu (v1.6 Aug 4 2005 15:27:38, -2.3/5.0 3.0.4) X-MailScanner: PASSED (v1.2.8 67228 k7GIcn7Z013008 mailbox8.ucsd.edu) 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++:3316 Matthias Hofmann wrote: > "mark" schrieb im Newsbeitrag > news:1155663179.843769.44420@b28g2000cwb.googlegroups.com... > > > > "Victor Bazarov" wrote: > >> Shouldn't this be moved to a .lang. newsgroup? Just checking... > >> > >> Frederick Gotham wrote: > >> > Thomas posted: > >> > > >> >> Hello fellow programmers! > >> >> > >> >> I have a c++ line: > >> >> > >> >> X x = X(); > >> >> > >> >> Does the standard say that the class X must have a public copy > >> >> constructor for this to be legal, even if the copy constructor never > >> >> gets called? > >> > > >> > > >> > Yes, although it gives explicit permission to the compiler to elide > >> > the creation of the redudant temporary object. Even if the temporary > >> > is elided, the copy-constructor must still be public. > >> > >> Not "public", *accessible*. If the "c++ line" above appears inside > >> a friend function, it would work just fine with a private copy c-tor. > > > > Yes. > > > >> If it appears inside a member of a derived class, "protected" should > >> suffice. > > > > Really? > > Yes, see section 11/1: "A member of a class can be [...] protected; that is, > its name can be used only by members and friends of the class in which it is > declared, and by members and friends of classes derived from this class." You left off the important part of the sentence (see 11.5), which says: . Except when forming a pointer to member (5.3.1), the access must be through a pointer to, reference to, or object of the derived class iteself (or any class derived from that class) (5.2.5). Mark Williams --- [ 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 ]