Re: How can I set up my class so it won't be inherited from?

From:

"Victor Bazarov" <v.Abazarov@comAcast.net>

Newsgroups:

comp.lang.c++

Date:

Fri, 8 Jun 2007 13:49:21 -0400

Message-ID:

<f4c4r2$j6h$1@news.datemas.de>

Nikolay Kurtov wrote:

http://www.parashift.com/c++-faq-lite/strange-inheritance.html#faq-23.11offers
a solution of the problem:

class Fred;

class FredBase {
private:
  friend class Fred;
  FredBase() { }
};

class Fred : private virtual FredBase {
public:
  ...
};

The only thing I want to know is why did he make FredBase a virtual
base. It works even if inheritance is non-virtual. Why virtual
inheritance is better??

How does it work if the inheritance non-virtual? What error does
your compiler report here:

class Fred;

class FredBase {
private:
   friend class Fred;
   FredBase() { }
};

class Fred : private /*virtual*/ FredBase {
};

class Foo : public Fred {};

class Bar : private Fred {};

int main() {
  Foo foo;
  Bar bar;
}

I've derived TWO classes from Fred and my compiler had no problem
letting me.

V
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