Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!rpi!image.soe.clarkson.edu!news From: cline@cheetah.ece.clarkson.edu (Marshall Cline) Newsgroups: comp.std.c++ Subject: Re: Casting within MI Graphs Message-ID: Date: 27 Aug 90 16:50:09 GMT References: <48168@brunix.UUCP> Sender: news@sun.soe.clarkson.edu Reply-To: cline@sun.soe.clarkson.edu (Marshall Cline) Organization: (I don't speak for the) ECE Dept, Clarkson Univ, Potsdam, NY Lines: 20 In-reply-to: sdm@cs.brown.edu's message of 24 Aug 90 19:28:07 GMT In article <48168@brunix.UUCP> sdm@cs.brown.edu (Scott Meyers) writes: > Does E&S prohibit explicit casts from pointers to virtual base classes to > pointers to derived classes? Yes, these casts, even though explicit, are illegal. The July issue of The C++ Report contains a C++ Puzzle solution showing why. Basically there is no way of knowing at compile time how to perform the cast. The cover article in the same issue shows a portable method of faking the cast. The method requires maintaining run-time type information. Marshall Cline -- ============================================================================== Marshall Cline / Asst.Prof / ECE Dept / Clarkson Univ / Potsdam, NY 13676 cline@sun.soe.clarkson.edu / Bitnet:BH0W@CLUTX / uunet!clutx.clarkson.edu!bh0w Voice: 315-268-3868 / Secretary: 315-268-6511 / FAX: 315-268-7600 Career search in progress; ECE faculty; research oriented; will send vita. PS: If your company is interested in on-site C++/OOD training, drop me a line! ==============================================================================