From -2116808050213380998 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: f78e5,6d5520f8ce526ad5 X-Google-Attributes: gidf78e5,public From: Christopher Eltschka Subject: Re: Pointer to member function restriction in standard Date: 2000/01/28 Message-ID: <38905F66.1645AA54@physik.tu-muenchen.de>#1/1 X-Deja-AN: 578344918 Content-Transfer-Encoding: 7bit Approved: Fergus Henderson , moderator of comp.std.c++ References: <388CC286.B7848872@hotmail.com> <86l2rq$r0i@library2.airnews.net> X-Accept-Language: German/Germany, de-DE, German, de, en X-Authentication-Warning: mulga.cs.mu.OZ.AU: fjh set sender to devnull@stump.algebra.com using -f Content-Type: text/plain; charset=us-ascii X-Complaints-To: abuse@demon.net X-Mail2News-Path: news.demon.net!mulga.cs.mu.oz.au X-Trace: mail2news.demon.co.uk 948987538 mail2news:15633 mail2news mail2news.demon.co.uk Organization: [posted via] Leibniz-Rechenzentrum, Muenchen (Germany) X-Robomod: STUMP, ichudov@algebra.com (Igor Chudov) Mime-Version: 1.0 Nntp-Posting-Date: 27 Jan 2000 15:14:41 GMT Newsgroups: comp.std.c++ Bill Wade wrote: > > Jim Cobban wrote in message <388CC286.B7848872@hotmail.com>... > >Could someone please explain to me the rationale behind the restriction > >documented in paragraph 3 of section 5.3.1 of the standard: > > > >"A pointer to member is only formed when an explicit & is used and ... > > My first guess: the guy who got this into the standard had once written > > while(foo){...} > > when he had intended > > while(foo()){...} > > he couldn't change the rule for existing pointer types, but could change > them for member pointers. > > My second guess: for object (data) members there needs to be a way to > disambiguate pointer-to-member, pointer-to-object, and object. If m is a > non-static data member of base then &base::m, &(base::m) and base::m mean > three different things. The standard is slightly simpler if the same rules > apply to both function members and data members. I think the problem is the use of the same operator& to provide both object pointers and member pointers. If there had been another operator, say operator&& (which currently would be interpreted as taking the address of an address, which is ill-formed), then there would be no problem in allowing &&(base::m) or even &&m to generate a pointer to member, while &(base::m) or &m would return a pointer to the object. --- [ 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://reality.sgi.com/austern_mti/std-c++/faq.html ]