From 1380045421184966653 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: f78e5,7ba7148d601bc33d X-Google-Attributes: gidf78e5,public X-Google-ArrivalTime: 2003-07-21 08:07:33 PST Path: archiver1.google.com!news1.google.com!newsfeed.stanford.edu!news.tele.dk!news.tele.dk!small.news.tele.dk!lnewspeer00.lnd.ops.eu.uu.net!emea.uu.net!kibo.news.demon.net!mutlu.news.demon.net!demon!mail2news.demon.co.uk!devnull From: richard@ex-parrot.com (Richard Smith) Newsgroups: comp.std.c++ Subject: Re: Should class-member using declarations behave differently from namespace using declarations? Date: Mon, 21 Jul 2003 15:07:32 +0000 (UTC) Organization: Posted via Supernews, http://www.supernews.com Lines: 39 Approved: fjh@cs.mu.oz.au (Fergus Henderson , moderator of comp.std.c++) Message-ID: References: <8c8b368d.0307160458.7889773@posting.google.com> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Trace: mail2news.demon.co.uk 1058800052 11168 10.0.0.1 (21 Jul 2003 15:07:32 GMT) X-Complaints-To: abuse@demon.net NNTP-Posting-Date: Mon, 21 Jul 2003 15:07:32 +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 19ecGB-0002tz-00 for mail2news@news.news.demon.net; Mon, 21 Jul 2003 15:07:32 +0000 X-Received: from localhost (localhost [[UNIX: localhost]]) by mulga.cs.mu.OZ.AU id BAA03753; Tue, 22 Jul 2003 01:07:28 +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-X-Sender: richard@sphinx.mythic-beasts.com X-Spam-Status: No, hits=-4.6 required=5.0 tests=AWL,BAYES_01,EMAIL_ATTRIBUTION,IN_REP_TO,QUOTED_EMAIL_TEXT, REFERENCES,REPLY_WITH_QUOTES,USER_AGENT_PINE autolearn=ham version=2.55 X-Spam-Checker-Version: SpamAssassin 2.55 (1.174.2.19-2003-05-19-exp) Xref: archiver1.google.com comp.std.c++:20238 Francis Glassborow wrote: > No you are perfectly right however I am not convinced that it should be. But it breaks encapsulation by allowing members of one class access to the private members of another. class B { private: int x; }; class D : public B { void f() { cout << x << endl; } }; This is an error: x is a private member of B so can't be accessed by D. Now consider add a using declaration to D: class D : public B { private: using B::x; void f() { cout << x << endl; } }; Now the name x is a private member of D, which can be accessed within D. By allowing this you allow derived classes to access *any* data member of a base class. I think this would be a very bad idea indeed. -- Richard Smith --- [ 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 ]