From 3276648754260580044 X-Google-Thread: f78e5,ac8f7c796c0ee2eb X-Google-Attributes: gidf78e5,public,usenet X-Google-Language: ENGLISH,ASCII Path: g2news1.google.com!news3.google.com!out01b.usenetserver.com!news.usenetserver.com!in02.usenetserver.com!news.usenetserver.com!pd7cy1no!shaw.ca!news.alt.net!comp-std-cpp-robomod!not-for-mail From: James Kanze Newsgroups: comp.std.c++ Subject: Re: std::pair istream >> operator Date: Tue, 27 Nov 2007 10:46:10 CST Organization: http://groups.google.com Lines: 49 Approved: Fergus Henderson , moderator of comp.std.c++ Message-ID: <01a449b0-f514-44ff-9949-5a65d6e2dc46@w34g2000hsg.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> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit X-Trace: posting.google.com 1196168026 22169 127.0.0.1 (27 Nov 2007 12:53:46 GMT) X-Complaints-To: groups-abuse@google.com NNTP-Posting-Date: Tue, 27 Nov 2007 12:53:46 +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: w34g2000hsg.googlegroups.com; posting-host=62.160.54.162; posting-account=1W_PtwoAAAA1QoMcl2Z5P6j-DNc8HR3W User-Agent: G2/1.0 X-HTTP-UserAgent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.8.1.9) Gecko/20071025 Firefox/2.0.0.9,gzip(gfe),gzip(gfe) Content-Disposition: inline X-Virus-Scanned: amavisd-new at ucar.edu X-Virus-Scanned: amavisd-new at csse.unimelb.edu.au X-MIME-Autoconverted: from quoted-printable to 8bit by mulga.csse.unimelb.edu.au id lARCrsoN024701 X-Virus-Scanned: amavisd-new at csse.unimelb.edu.au Xref: g2news1.google.com comp.std.c++:9693 On Nov 26, 6:42 pm, Martin wrote: > On 21 Nov, 18:54, Andrey wrote: [...] > Then you have the problem with the width stream manipulator. > Don't know how the tuple streaming handles it but I do know > that complex got it all wrong. For complex the width is > applied to the result string and not the items. > cout << width(5) << complex(1,2) > becomes > "1,2 " > which makes it impossible to line up the items. If the width > is applied to each item you can always use an intermediate > string stream to limit the width of the result string. The solution I'd always seen (in pre-standard complex) was to apply (width()-3)/2 to each of the components of the complex. > 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. A format which would be appropriate for e.g. an element in a map would certainly not be appropriate in other cases, even if the types are identical. 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. -- James Kanze (GABI Software) email:james.kanze@gmail.com Conseils en informatique orient�e objet/ Beratung in objektorientierter Datenverarbeitung 9 place S�mard, 78210 St.-Cyr-l'�cole, France, +33 (0)1 30 23 00 34 --- [ 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 ]