Re: Inheritance Problem (MSVC 6)

From:
"Victor Bazarov" <v.Abazarov@comAcast.net>
Newsgroups:
comp.lang.c++
Date:
Fri, 8 Jun 2007 13:35:03 -0400
Message-ID:
<f4c408$hsc$1@news.datemas.de>
Hans-Dieter Dreier wrote:

Hi NG,

I have an inheritance like this:

class a_interface
{
virtual bool x() = 0;
};

class a_version_1 : public a_interface
{
virtual bool x() {return true;}
}

class a_version_2: public a_interface
{
virtual bool x() {return false;}
}

class b_interface: public a_interface
{
};

class b_derived: public a_interface, public a_version_1


I think you meant

 class b_derived: public b_interface, public a_version_1

{
};

class b_interface is never instantiated, only its derived classes are
(there are lots of them, some need a_version1, some a_version2).
When I try to create an instance of b_derived, I get the error "pure
virtual function not defined". Why doesn't it take bool x() from
a_version_1?
Is this a bug in Visual Studio 6?


No.

What can I do about it, if I need to access a_interface from within
b_interface, other than re-implementing a_version_x in every derived
class?


First of all, your 'a_interface' should probably be derived from
*virtually*. Have you tried that?

V
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