From 5550333285834956531 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: f78e5,cc1a555bbe9617a3 X-Google-Attributes: gidf78e5,public From: Matt Austern Subject: Re: STL and SGI and strings Date: 1998/01/13 Message-ID: #1/1 X-Deja-AN: 315647366 References: <34B57837.41C6@pixar.com> <34B6580F.6A50@pratique.fr> <69e5d5$eki$1@news2.ispnews.com> X-Original-Date: 13 Jan 1998 09:25:49 -0800 Originator: austern@isolde.mti.sgi.com Organization: SGI X-Auth: PGPMoose V1.1 PGP comp.std.c++ iQBVAwUBNLvX1Uy4NqrwXLNJAQHsEAH+IUjrDQV2wO1hMUBhwrBb9Rm4Kzgl2Dx8 KkBimgXCJgXXhfTgztVghACBoe83PGsNy06sNpg30LX2WendtFFGMQ== =oTPT Newsgroups: comp.std.c++ "Brock" writes: > >The problem is that sharing is often impossible as: > >- operator[] has to return a charT& > > > Does it have to return a charT& according to the standard? I read somewhere > (More Effective C++?) about an efficient way to determine whether operator[] > was used for read or write access by returning an object with an overloaded > operator=(charT), and an operator charT(). I even wrote a (hopeless) email > to my vendor (MS) complaining that their std::string implementation didn't > use this technique, as I had assumed it to be the standard way to do it. Yes, the standard does require that that basic_string<>::operator[] return a charT&. Proxy references are not allowed. Changing from charT& to a proxy reference class is not an implementation detail, but a visible change in the interface. To take one trivial example: at present, if s is a string, the expression std::swap(s[0], s[1]) is legal. If operator[] returned a proxy reference, though, it would not be. --- [ comp.std.c++ is moderated. To submit articles: Try just posting with your newsreader. If that fails, use mailto:std-c++@ncar.ucar.edu comp.std.c++ FAQ: http://reality.sgi.com/austern/std-c++/faq.html Moderation policy: http://reality.sgi.com/austern/std-c++/policy.html Comments? mailto:std-c++-request@ncar.ucar.edu ]