Re: C++ polymorphism question

On 19 Sep, 12:22, Jonas Huckestein <swap mac....@jonas.huckestein>
wrote:


This would be allowed;

class A
{
public:
  virtual void oskar(); // style issue: do not put void parameter in
but technically allowed

 // A should also have a virtual destructor the way you use it thus:
  virtual ~A() {}
};

class B : public A // note it must inherit public to use the
inheritance outside of class B itself
{
   void emil(){};

   void oskar() // it is allowed to be private here and will still
work
   {
     emil();
   }
};

int main() // or any other function
{
  A * peter = new B;
  peter->oskar(); // allowed as long as oskar is public in A or this
function is a friend

  delete peter; // and hope oskar() didn't throw, so preferably use
auto_ptr or scoped_ptr
        // but we are illustrating access here
}

Another popular "style" issue is to make the virtual method protected
in A and have a public non-virtual method call it. (It is better to
make it protected rather than private, not because the derived class
can't override the private virtual, it can, and not because it "looks
confusing" (like the FAQ says) but because it cannot implement in
terms of its base class implementation).