From 2123115009759970042 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: f78e5,fcf9039f47123dd0 X-Google-Attributes: gidf78e5,public X-Google-ArrivalTime: 2004-04-28 08:57:33 PST Path: archiver1.google.com!news1.google.com!news.glorb.com!news2.euro.net!news2.euro.net!kibo.news.demon.net!mutlu.news.demon.net!demon!mail2news.demon.co.uk!devnull From: Michiel.Salters@logicacmg.com (Michiel Salters) Newsgroups: comp.std.c++ Subject: Re: Dear All, Date: Wed, 28 Apr 2004 15:57:32 +0000 (UTC) Organization: http://groups.google.com Lines: 44 Approved: fjh@cs.mu.oz.au (Fergus Henderson , moderator of comp.std.c++) Message-ID: References: <408df3b1$0$436$afc38c87@news.optusnet.com.au> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit X-Trace: mail2news.demon.co.uk 1083167852 16906 10.0.0.1 (28 Apr 2004 15:57:32 GMT) X-Complaints-To: abuse@demon.net NNTP-Posting-Date: Wed, 28 Apr 2004 15:57:32 +0000 (UTC) X-Received: from mulga.cs.mu.oz.au ([128.250.1.22]) by news.demon.co.uk with esmtp (Exim 4.12) id 1BIrRD-0004OW-00 for mail2news@news.news.demon.net; Wed, 28 Apr 2004 15:57:31 +0000 X-Received: from mulga.cs.mu.OZ.AU (localhost [127.0.0.1]) by mulga.cs.mu.OZ.AU with ESMTP id i3SFvTi2029788; Thu, 29 Apr 2004 01:57:29 +1000 (EST) X-Received: (from fjh@localhost) by mulga.cs.mu.OZ.AU (8.12.10+Sun/8.12.9/Submit) id i3SFvT3C029778; Thu, 29 Apr 2004 01:57:29 +1000 (EST) X-Authentication-Warning: mulga.cs.mu.OZ.AU: fjh set sender to devnull@stump.algebra.com using -f X-Path: comp-std-cpp-robomod!not-for-mail X-Robomod: STUMP, ichudov@algebra.com (Igor Chudov) X-Delivered-To: std-c++@ucar.edu X-Newsgroups: comp.std.c++ X-NNTP-Posting-Date: Wed, 28 Apr 2004 12:24:39 +0000 (UTC) X-Spamscanner: mailbox1.ucsd.edu (v1.4 Mar 10 2004 15:18:19, 0.0/5.0 2.63) X-MailScanner: PASSED (v1.2.8 2351 i3SCOerr012514 mailbox1.ucsd.edu) X-Spam-Level: X-Spam-Checker-Version: SpamAssassin 2.60-mulga_r1 (1.212-2003-09-23-exp) on mulga.cs.mu.OZ.AU X-Spam-Status: No, hits=0.1 required=5.2 tests=AWL autolearn=no version=2.60-mulga_r1 Xref: archiver1.google.com comp.std.c++:2006 nesotto@cs.auc.dk ("Thorsten Ottosen") wrote in message news:<408df3b1$0$436$afc38c87@news.optusnet.com.au>... [propoped] > template< class Vector, class Matrix > > Vector mean_vector( const Matrix& ); > > Matrix m; > Vector v = mean_vector( m ); > > as if mean_vector() returns a proxy with all possible conversion operators > defined ? > > remark: given a templated conversion operator in a proxy we could > return the proxy from mean_vector() > to make it work. However, that incurs a large overhead. Why would there be a large overhead? template< typename Matrix > class mean_vector_return { friend mean_vector_return( Matrix const& argument ); Matrix const& argument; public: template< typename Vector > operator Vector() { /* real implementation */ } }; template< typename Matrix > inline mean_vector_return mean_vector( Matrix const& argument ) { return mean_vector_return( argument ); } Basically, everything except the operator T could be inlined. The operator Vector actually implements the intended mean_vector() function. Regards, Michiel Salters --- [ 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.jamesd.demon.co.uk/csc/faq.html ]