some fun with C++

Was playing around with C++, and found that you can actually use a base class member function pointer to call functions defined in derived class. Round about way, but useful for implementing stuff like: http://en.wikipedia.org/wiki/Future_%28programming%29

Here is an example snippet:

#include ... 
class Base { 
  public: 
    typedef void (Base::*WhoPtr)(); 
}; 
class D1: public Base { 
  public: 
    void WhoAmI() const; 
}; 
class D2: public Base { 
  public: 
    void WhoAmI() const; 
}; 
void D1::WhoAmI() const { 
  std::cout << "I am D1" << std::endl; 
} 
void D2::WhoAmI() const { 
  std::cout << "I am D2" << std::endl; 
} 
void run(Base::WhoPtr fptr) {
  Base base;   
  (base.*fptr)();  
}
int main(int argc, char **argv ) { 
  Base::WhoPtr func; 
  func = (void (Base::*)()) &D1::WhoAmI;
  run(func);
  func = (void (Base::*)()) &D2::WhoAmI;
  run(func);
  return 0; 
}