From 2463177683519186427 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: f78e5,3cdb654b702f7476 X-Google-Attributes: gidf78e5,public X-Google-Thread: 109fba,3cdb654b702f7476 X-Google-Attributes: gid109fba,public From: "Gerhard W. Gruber" Subject: Re: virtual functions Date: 2000/08/18 Message-ID: <399B909C.654107BA@gmx.at>#1/1 X-Deja-AN: 659802629 Content-Transfer-Encoding: 7bit Approved: Fergus Henderson , moderator of comp.std.c++ References: <399A78E4.8345D7B@gmx.at> X-Accept-Language: en 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 966619272 mail2news:18281 mail2news mail2news.demon.co.uk X-Robomod: STUMP, ichudov@algebra.com (Igor Chudov) MIME-Version: 1.0 Newsgroups: comp.lang.c++,comp.std.c++ Anders Pytte wrote: > The compiler will not allow you to call a non-static member function of an > object that has not been constructed. Disappointing, isn't it? However, > there are good reasons for this rule. > > I've developed two techniques to accomplish what you are trying to do. > > The first is to pass a function in a constructor's parameter list. Then the > base class can call a function provided by the derived class. The function > may not be a non-static member of the derived class, but it can be a static > member function that takes a base class reference as a parameter. I already tried this, but this brought me an "internal compiler error please contact...". :) Also I consider this approach as somewhat ugly. But it is better than nothing. :) > My other approach has been to define a "post init" function in a base class > which is called by public constructors of both the base and derived class. > This requires awkward protected constructors in base classes that don't call > the "post init" function and whose only purpose is to initialize the base > sub-object in the derived object's constructor. I'm not sure if I understand this right, but I think that I implemented it that way. This resulted in multiple calls to the init function. That's not really nice, but I can live with it, if there is no other way around. Another idea I had was to use to a bit of assembly code to enforce the initialization, but that's even worse. :) --- [ 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 ]