From -4898261277073406109 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: f78e5,d172be9423d7e292 X-Google-Attributes: gidf78e5,public From: Christopher Eltschka Subject: Re: virtual versus dynamic Date: 1999/02/02 Message-ID: <36B73CB0.7D37DA29@physik.tu-muenchen.de>#1/1 X-Deja-AN: 439843728 X-Nntp-Posting-Host: coulomb.t30.physik.tu-muenchen.de Content-Transfer-Encoding: 7bit Approved: stephen.clamage@sun.com (comp.std.c++) References: <917861033.740809@saturn.riv.be> X-UID: 0000000001 X-Status: $$$T Content-Type: text/plain; charset=us-ascii Organization: [posted via] Leibniz-Rechenzentrum, Muenchen (Germany) Mime-Version: 1.0 Newsgroups: comp.std.c++ Originator: clamage@taumet Chris Minnoy wrote: > > While I was experimenting with Delphi I noticed a rather remarkable feature > that C++ doesn't support, namely dynamic methods. Dynamic methods are, just > like virtual methods, late binded. The difference is size and speed. > In the Delphi helpfile I found: > > A method is made dynamic by including a dynamic directive in its declaration. > Dynamic methods are semantically identical to virtual methods. This sentence settles the issue. The standard only tells you the semantics, not the implementation of virtual functions. Compilers are allowed to implement virtual functions with the Delphi dynamic method mechanism as well as with the usual vtbl mechanism. It is even allowed to decide the used scheme on a case-by-case analysis, or to make it dependant on compiler options, pragmas, or even the method name (i.e. a compiler which used dynamic invocation for all methods starting with dyn would be conforming - not that I would like it). Also, the compiler doesn't need to do any of those - it could do a type id, and use a big switch statement internally. Or do an if for the most common case, and use a vtbl or "dtbl" otherwise. [...] [ 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 ]