Re: abstract base class question

From:

"Thomas J. Gritzan" <Phygon_ANTISPAM@gmx.de>

Newsgroups:

comp.lang.c++

Date:

Sun, 09 Jul 2006 23:06:38 +0200

Message-ID:

<e8rr4u$3nm$1@newsreader2.netcologne.de>

rami schrieb:

Alf P. Steinbach wrote:

* rami:

AFAIK, pure virtual functions with bodies can be invoked from the
derived classes only..

Try this with your favorite compiler:

   #include <iostream>
   #include <ostream>

   void say( char const s[] ) { std::cout << s << std::endl; }

   struct Foo
   {
       virtual void bar() const = 0;
       void g() const { Foo::bar(); }
   };

   void Foo::bar() const { say( "called" ); }

   struct Foo2: Foo { void bar() const {} };

   int main() { Foo2().g(); }

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Thanks!

So is the point - "can only be called _through_ the derived class
objects"?

Please don't quote signatures. Good newsreaders cut them automatically.

The point is that there is no restriction on how you can call pure
virtual functions.

However, you cannot instantiate a class with pure virtual functions (you
cannot have objects of this class).

--
Thomas