Re: Override and Virtual function checking in C++

From:

Thorsten Ottosen <thorsten.ottosen@dezide.com>

Newsgroups:

comp.lang.c++.moderated

Date:

3 Aug 2006 17:51:05 -0400

Message-ID:

<44d25a9f$0$60779$157c6196@dreader1.cybercity.dk>

Leo Wong wrote:

Hi,

With a lot of classes and virtual functions to work with, it is
increasingly difficult to track incorrectly defined virtual functions

That is not the only problem *public* with virtual functions, but that's
another issue.

I haven't tested these extensively but one of the problem is that the
macros are not taking into account the parameters in the virtual
functions. The side effect is that they won't allow you to declare
multiple virtual functions with the same name in the same class with
different parameters.

Somebody brought up this very simply idea, he is known in the C++
community (I forgot his name). The idea is simply and beautiful
(although it does not work at the interface level):

#define OVERRIDE( fun_and_params ) if( false ) fun_and_params

struct Base
{
     virtual void foo() {}
     virtual void foo1( int ) {}
};

struct Derived : Base
{
     virtual void foo()
     {
         OVERRIDE( Base::foo() );
     }

     virtual void foo1( int i )
     {
         OVERRIDE( Base::foo1(i) );
     }
};

int main()
{
     Base* p = new Derived;
     p->foo();
     p->foo1(3);
}

-Thorsten

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