From -5712941791436912274 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: f78e5,edd477ec92e5348f X-Google-Attributes: gidf78e5,public X-Google-Thread: fc772,ef0c226459c03bdf X-Google-Attributes: gidfc772,public From: Francis Glassborow Subject: Re: Protected Inheritance Date: 1999/02/07 Message-ID: #1/1 X-Deja-AN: 442759302 Approved: kuehl@fmi.uni-konstanz.de Sender: cppmods@netlab.cs.rpi.edu References: <79aesq$qlr$1@uuneo.neosoft.com> <7sAoNOBfshu2EwFV@robinton.demon.co.uk> X-Submission-Address: c++-submit@netlab.cs.rpi.edu X-Approved-For-Group: Fergus Henderson comp.std.c++ X-Original-Date: 07 Feb 99 16:51:14 GMT Organization: Southfield Microcomputer SS X-Auth: PGPMoose V1.1 PGP comp.lang.c++.moderated iQBVAwUANr3x1kHMCo9UcraBAQHG7QH/QPMlbfh0SfhNW5MLbxXpkQhf3IlL9GlZ c4r7gDYyYF2uUotJcNORPOncpe7LbtqnXBI0JbKMdudj4aQgOv1Zdg== =uHRc Reply-To: Francis Glassborow Newsgroups: comp.lang.c++.moderated,comp.std.c++ In article , Larry Brasfield writes >I think calling that inheritance structure "a waste of >time" is to lose sight of what is being controlled by >making derivation private. It is not so much to guard >the base against outside corruption as to restrict the >interface exposed by the derived class. The above >private (virtual) inheritance does that for class B. The >fact that class C (or its designer, more accurately) has >chosen to expose its A base is C's (designer's) affair, >of no concern to the design of B. Presumably, what >utility A had for B survives sharing (which is implicit >in virtual inheritance) by classes that derive from B. >That utility is independent of whether those classes >elect to expose A as part of their interface. My feeling is that the concept is better provided by using virtual protected inheritance. I guess that is a style issue, but it does I think, warn less experienced designers that the inheritance they are using provides less protection than they might expect. Francis Glassborow Chair of Association of C & C++ Users 64 Southfield Rd Oxford OX4 1PA +44(0)1865 246490 All opinions are mine and do not represent those of any organisation --- [ 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 ]