From -8027958791542002712 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: f78e5,7eaa8faac8da5016 X-Google-Attributes: gidf78e5,public From: dHarrison@worldnet.att.net (Doug Harrison) Subject: Re: Defect Report: member == in container iterators considered harmful Date: 1999/08/18 Message-ID: <37ceebde.11431046@netnews.worldnet.att.net>#1/1 X-Deja-AN: 514108266 Content-Transfer-Encoding: 7bit Approved: Fergus Henderson References: <7p4nj8$n3u@enews4.newsguy.com> <37B95B96.7F37@wanadoo.fr> X-Original-Date: Tue, 17 Aug 1999 23:11:56 GMT Content-Type: text/plain; charset=us-ascii Organization: AT&T WorldNet Services X-Auth: PGPMoose V1.1 PGP comp.std.c++ iQBFAgUAN7pPyuEDnX0m9pzZAQFi/wF9GU0zu1fYeRZ0VnjRaCszlpj48OpR9fyK eoSaJVfj20M27CiJyMV841XFdLCeVLn8 =TgIk Mime-Version: 1.0 Newsgroups: comp.std.c++ Valentin Bonnard wrote: >> bool check_equal(std::deque::iterator i, >> std::deque::const_iterator ci) >> { >> return i == ci; >> } >> >> The reason for this is that there's no requirement that the == operator be >> defined as a non-member function. > >It's the contrary: as a non member function, deduction >won't ever work. Who says std::deque::iterator has to be a member class? It could be defined as std::__deque_iterator, and deque::iterator could just be a typedef for it. It may not help you portably write a templated check_equal, but it certainly helps the library implementer provide symmetric operator==. >So mandating non member functions certainly: >- isn't a solution I think it's a solution for operator== et. al. Note that deque::iterator is a random access iterator and thus has to support symmetric operator+ anyway. This requires a non-member operator+ so you can say "n+i", where n is difference_type and i is iterator. >- goes agains the spirit of generic programming Why? -- Doug Harrison dHarrison@worldnet.att.net --- [ 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 ]