From -1714896835518659441 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: f78e5,7eaa8faac8da5016 X-Google-Attributes: gidf78e5,public From: sbnaran@uiuc.edu (Siemel B. Naran) Subject: Re: Defect Report: member == in container iterators considered harmful Date: 1999/08/19 Message-ID: #1/1 X-Deja-AN: 514751389 X-NNTP-Posting-Host: rochester-30.slip.uiuc.edu Approved: stephen.clamage@sun.com (comp.std.c++) References: <7p4nj8$n3u@enews4.newsguy.com> <7pcj1q$105@library1.airnews.net> X-UID: 0000000001 X-Status: $$$T Organization: University of Illinois at Urbana-Champaign User-Agent: slrn/0.9.5.7 (UNIX) Reply-To: sbnaran@uiuc.edu Newsgroups: comp.std.c++ Originator: clamage@taumet On 18 Aug 1999 05:18:50 GMT, Bill Wade wrote: >Darin Adler wrote in message <7p4nj8$n3u@enews4.newsguy.com>... >>If they are, any ==, !=, >, <, >=, or <= operator functions defined >>for these classes to satisfy iterator requirements must be defined in the >>std namespace, not as member functions. >I'm not on the committee, but I believe the above is overly restrictive. >Here are two ways that member functions can support the desired test ( i == >ci; // iterator i; const_iterator ci). > >1) bool iterator::operator==(const_iterator) const; >2) class iterator: public const_iterator { ... }; // inherit operator==() I must have missed something. If the conversion from 'iterator' to 'const_iterator' is implicit, then we could also use a non-member operator==(const_iterator,const_iterator), optionally a friend. So there is a choice 3) too, right? I wrote my own iterator class iter, and iterator is iter and const_iterator is iter. To write seperate classes class iter and const_iter is tedious. So I don't like 1) or 2). If I had an implicit conversion iter::iter(const iter&); then choice 3) is feasible (eg, T==int and U==const int). However, for most type safety and best error messages, I don't want this templated implicit constructor, so choice 3) I also don't like. -- ---------------------------------- Siemel B. Naran (sbnaran@uiuc.edu) ---------------------------------- [ 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 ]