From -8289769610306207823 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: f78e5,3cdb654b702f7476 X-Google-Attributes: gidf78e5,public From: llewelly.@@edevnull.dot.com Subject: Re: virtual functions Date: 2000/08/18 Message-ID: #1/1 X-Deja-AN: 659692236 Approved: Fergus Henderson , moderator of comp.std.c++ References: <399A78E4.8345D7B@gmx.at> <399B8FA6.540D5B7F@gmx.at> X-Authentication-Warning: mulga.cs.mu.OZ.AU: fjh set sender to devnull@stump.algebra.com using -f Content-Type: text/plain; charset=us-ascii X-Complaints-To: abuse@demon.net X-Mail2News-Path: news.demon.net!mulga.cs.mu.oz.au X-Trace: mail2news.demon.co.uk 966597940 mail2news:4425 mail2news mail2news.demon.co.uk Organization: XMission http://www.xmission.com/ X-Robomod: STUMP, ichudov@algebra.com (Igor Chudov) User-Agent: Gnus/5.0806 (Gnus v5.8.6) Emacs/20.7 Mime-Version: 1.0 NNTP-Posting-Date: 17 Aug 2000 23:52:37 GMT Newsgroups: comp.std.c++ "Gerhard W. Gruber" writes: > "llewelly."@@edevnull.dot.com wrote: > > > Your compiler is correct in this case; if a virtual function is called > > from inside a constructor, the method of that class - *not* the > > overriding method - is called. > > Is this only true for the constructor? From your statement it appears > so, but I'm not sure on this. It is true only inside constructors *and* destructors. In all other cases, the overriding method of the object's dynamic type is called. > > > It seems to me that a virtual initialization method such as what you > > want implies a close coupling between the implementation of the base > > class's constructor and the derived class. How could the author of > > the overriding virtual initialization method know what to > > initialize without understanding the implementation of the base > > class's constructor? Such tight coupling is usually poor design, as > > it makes derived classes likely to break when the implementation of > > the base class is changed. > > I don't really see why this should be poor design. When I call the base > class constcructor, I can assume that the class is properly initialized > (That's what the constructor is for, isnt't it?). So when the base class > constructor returns I can change part of the initialization in the > derived class that fits the derivation. Isn't that so? I think we are talking about two different things. I had the impression that the virtual initialization function was to be called *before* the base class constructor had returned. Reconfiguring the base class sub object after it has been correctly initialized seems less error prone. [snip] --- [ 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://reality.sgi.com/austern_mti/std-c++/faq.html ]