From 5405710969608566535 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: f78e5,c997c315a835018d X-Google-Attributes: gidf78e5,public X-Google-ArrivalTime: 1993-10-11 17:54:37 PST Newsgroups: comp.std.c++ Path: gmd.de!xlink.net!howland.reston.ans.net!europa.eng.gtefsd.com!uunet!tadpole.com!news.dell.com!swrinde!menudo.uh.edu!uuneo!sugar!jabberwock!daniels From: daniels@biles.com (Brad Daniels) Subject: Re: Implicit conversions for pointer-to-member References: <60.1231.4352.0N18601B@canrem.com> Organization: Biles and Associates Date: Mon, 11 Oct 1993 22:01:56 GMT Message-ID: Lines: 33 In article <60.1231.4352.0N18601B@canrem.com>, Gordan Palameta wrote: >Let D be a derived class of B, and Foo is some other class. > > >Is this legal without an explict cast? > > B Foo::* <-- D Foo::* > >HP C++ 3.0 (based on cfront) seems to think so, IBM C++ and DEC C++ >disagree. > >I would think that this is really no different from the ordinary > > B * <-- D * > >and therefore should be allowed. Language issues aside, the difference between the two cases is that the conversion from D * to B * (or D to B - it's not clear which you're talking about, but it doesn't matter anyway) may require additional code. That code will not exist in a D::* member function, so when you invoke the D::* function through a B::* member function, you will get an actual D::* pointer interpreted as a B::*. This situation is usually benign in a single inheritance situation, but you will almost definitely get in trouble if D also inherits from something other than B. - Brad -- ---------------------------------------------------------------------- + Brad Daniels | "Let others praise ancient times; + + Biles and Associates | I am glad I was born in these." + + These are my views, not B&A's | - Ovid(43 B.C - 17 A.D) +