From -2149306994529748207 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: f78e5,7eaa8faac8da5016 X-Google-Attributes: gidf78e5,public From: Pete Becker Subject: Re: Defect Report: member == in container iterators considered harmful Date: 1999/08/19 Message-ID: <37BB70ED.5895619C@acm.org>#1/1 X-Deja-AN: 514751373 X-NNTP-Posting-Host: 24.128.201.83 Content-Transfer-Encoding: 7bit Approved: stephen.clamage@sun.com (comp.std.c++) References: <7p4nj8$n3u@enews4.newsguy.com> <37B98C2E.E3A1EA71@acm.org> <37B98D53.3B7@wanadoo.fr> <37B9A195.B7090C3C@acm.org> X-Accept-Language: en X-UID: 0000000001 X-Status: $$$T Content-Type: text/plain; charset=us-ascii X-Complaints-To: abuse@mediaone.net X-Trace: wbnws01.ne.mediaone.net 935031014 24.128.201.83 (Wed, 18 Aug 1999 22:50:14 EDT) Organization: Road Runner Mime-Version: 1.0 NNTP-Posting-Date: Wed, 18 Aug 1999 22:50:14 EDT Newsgroups: comp.std.c++ Originator: clamage@taumet blargg wrote: > > In article <37B9A195.B7090C3C@acm.org>, Pete Becker wrote: > > > That way you don't have to worry about getting the type of the > > iterator right. But the mistake in that particular loop is the decision > > to use a const_iterator without regard to the actual constness of the > > container. > > I suppose if you were given a pointer-to-non-const, you wouldn't consider > ever converting that to a pointer-to-const? > Of course I would. Pointers are usable as STL iterators by necessity, but it doesn't follow that everything you can do with a pointer is also appropriate for an iterator. > > Write it this way: > > > > for (Container::iterator it = cont.begin(); it != cont.end(); ++it) > > foo(*it); > > What if we only want to inspect the container, and enforce this decision > by using a const iterator? > Constness admittedly doesn't fit well in STL -- it was added in after the fact. But hacking around with modifications to operator== almost certainly isn't the right solution. So I'll repeat my question, which nobody so far has tried to address except by one-liners: But the begin and end iterators that you get from a container are of the same type, and they work just fine for the standard STL idioms. Why do you need to do this? What coding practices does it support? -- Pete Becker Dinkumware, Ltd. http://www.dinkumware.com [ 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 ]