From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-1.3 required=5.0 tests=BAYES_00,INVALID_MSGID autolearn=no autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 109fba,b87849933931bc93 X-Google-Attributes: gid109fba,public X-Google-Thread: fac41,b87849933931bc93 X-Google-Attributes: gidfac41,public X-Google-Thread: 103376,b87849933931bc93 X-Google-Attributes: gid103376,public X-Google-Thread: 1108a1,b87849933931bc93 X-Google-Attributes: gid1108a1,public X-Google-Thread: f43e6,b87849933931bc93 X-Google-Attributes: gidf43e6,public X-Google-Thread: 114809,b87849933931bc93 X-Google-Attributes: gid114809,public From: fjh@murlibobo.cs.mu.OZ.AU (Fergus Henderson) Subject: Re: What is wrong with OO ? Date: 1997/02/22 Message-ID: <5elsul$pjh@mulga.cs.mu.OZ.AU>#1/1 X-Deja-AN: 220588233 References: <32D11FD3.41C6@wi.leidenuniv.nl> <01bbd23a$5b667cc0$LocalHost@christophe-leph> <01bc0269$3fd55b20$ca61e426@DCorbit.solutionsiq.com> <32FF1199.615E@calfp.co.uk> <3303A993.759E@pratique.fr> <330D930A.2850@calfp.co.uk> Organization: Comp Sci, University of Melbourne Newsgroups: comp.lang.c++,comp.lang.smalltalk,comp.lang.eiffel,comp.lang.ada,comp.object,comp.software-eng Date: 1997-02-22T00:00:00+00:00 List-Id: Nick Leaton writes: >Valentin Bonnard wrote: >> >> Nick Leaton wrote: >> > >> > richard@highrise.nl wrote: >> > > >> > > Virtual functions are also a kind of documentation. When declaring a >> > > function virtual, the programmer is more or less saying "go ahead, >> > > override this function if you like." >> > >> > The decision to make a function virtual assumes a knowledge of what >> > users of your class are going to do. It akin to predicting the future. >> >> No. If it make sense to override, make it virtual; if it doesn't, >> don't make it virtual. > >If you can forsee the future! It's not about forseeing the future, it's about programming by contract and making appropriate design decisions. >We are only talking about classes that inherit, not classes that >use. Why shouldn't a class that inherits another get access to >implementation details? Because those implementation details may change! >OK, Microsoft release a duff library with a duff class. You >have no source. Will Microsoft give you the source? No. You >have to inherit and overide. It is ugly, it is not ideal, but >you have no choice. That is a perfect example of why you should *not* do this, because if you do, then Microsoft will screw you when they release the next version. In the next version, they will have declared what you thought was a bug to be a feature, and they will have lots of code that depends on it. -- Fergus Henderson | "I have always known that the pursuit WWW: | of excellence is a lethal habit" PGP: finger fjh@128.250.37.3 | -- the last words of T. S. Garp.