From -3105075708311926496 X-Google-Thread: f78e5,ac8f7c796c0ee2eb X-Google-Attributes: gidf78e5,public,usenet X-Google-Language: ENGLISH,ASCII-7-bit Path: g2news1.google.com!news3.google.com!out03a.usenetserver.com!news.usenetserver.com!in01.usenetserver.com!news.usenetserver.com!news.alt.net!comp-std-cpp-robomod!not-for-mail From: Martin Newsgroups: comp.std.c++ Subject: Re: std::pair istream >> operator Date: Wed, 28 Nov 2007 11:55:57 CST Organization: http://groups.google.com Lines: 70 Approved: Fergus Henderson , moderator of comp.std.c++ Message-ID: <320d4cda-ad86-4c19-83ea-8c3fcc23e110@s36g2000prg.googlegroups.com> References: <92a741eb-f9f2-40dc-b252-5f53a451af13@w34g2000hsg.googlegroups.com> <84eb137f-aa46-443e-8f6a-912487da73ad@p69g2000hsa.googlegroups.com> <63447783-3e0d-41f8-98a6-62f69025e631@d50g2000hsf.googlegroups.com> <01a449b0-f514-44ff-9949-5a65d6e2dc46@w34g2000hsg.googlegroups.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Trace: posting.google.com 1196244220 18508 127.0.0.1 (28 Nov 2007 10:03:40 GMT) X-Complaints-To: groups-abuse@google.com NNTP-Posting-Date: Wed, 28 Nov 2007 10:03:40 +0000 (UTC) Return-Path: X-Authentication-Warning: mulga.csse.unimelb.edu.au: fjh set sender to devnull@stump.algebra.com using -f X-Robomod: STUMP, ichudov@algebra.com (Igor Chudov) X-Original-To: std-c++@mailman.ucar.edu Delivered-To: std-c++@mailman.ucar.edu X-SMTP-Auth: no Complaints-To: groups-abuse@google.com Injection-Info: s36g2000prg.googlegroups.com; posting-host=62.95.16.58; posting-account=6obM4goAAAAihX2IqW0281fEd31oVBnX User-Agent: G2/1.0 X-HTTP-UserAgent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.4) Gecko/20070515 Firefox/2.0.0.4,gzip(gfe),gzip(gfe) X-HTTP-Via: 1.1 fw.touchdown.se:8080 (squid/2.6.STABLE4) Content-Disposition: inline X-Virus-Scanned: amavisd-new at ucar.edu X-Virus-Scanned: amavisd-new at csse.unimelb.edu.au X-Virus-Scanned: amavisd-new at csse.unimelb.edu.au Xref: g2news1.google.com comp.std.c++:9713 > The solution I'd always seen (in pre-standard complex) was to > apply (width()-3)/2 to each of the components of the complex. The draft standard says about stream::operator<< Effects: inserts the complex number x onto the stream o as if it were implemented as follows: template basic_ostream& operator<<(basic_ostream& o, const complex& x) { basic_ostringstream s; s.flags(o.flags()); s.imbue(o.getloc()); s.precision(o.precision()); s << '(' << x.real() << "," << x.imag() << ')'; return o << s.str(); } > > > If I could put in a recommendation it would be: > > - Add a separator field to the ios_base structure (default = > > traits::eof() -> ctype.isspace for input and space for output) > > - Add manipulators: separator, setseparator, showseparator, > > noshowseparator (default) > > - Width, fill etc applies to each item (but not the separator) > > - separator is also used to end stream input for string. > > None of which addresses the basic problem of outputting > std::pair (or boost::tuple): the fact that the type may have > different semantic signification at different places in the > program. Isn't that something that applies to all types? Built in types like double got modifers on format, precision etc. If you need some non-standard formatting you implement your own but it still nice to have a default. > Although there may be some special cases, my own feeling is that > any use of std::pair (and probably most uses of boost::tuple) > are simply poor programming. I agree but admit I'm using them a lot. Specially in containers. To make your own "named_tuple" you need to implement the operators as well. I have some macros to do it but it quickly get inconvenient. If I temporary need a set or map with 2 values inside a funtion I just do a single line typedef std::map > mymap; To do it with a macro you first need to create the type outside the function (template types need external linkage) which could be in .h file somewhere. NAMED_TUPLE(mytuple, std::string, name, int, value); . typedef std::map mymap; It would be nice with a feature like the anonymous types in C# 3. --- [ 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://www.comeaucomputing.com/csc/faq.html ]