this->vpointer[vfunctionIndex](regular_arguments)

class Shape
{
public:
  virtual double area() = 0;
  virtual ~Shape() {}
};

class Triangle
  : public Shape
{
protected:
  double base;
  double height;
public:
  Triangle( double newBase, double newHeight )
    : base( newBase ), height( newHeight )
  {
  }
  virtual double area()
  {
    return base * height / 2.0;
  }
  virtual ~Triangle() {}
};

class Square
  : public Shape
{
protected:
  double side;
public:
  Square( double newSide )
    : side( newSide )
  {
  }
  virtual double area()
  {
    return side * side;
  }
  virtual ~Square() {}
};

typedef class ShapeLinkedListPair * ShapeLinkedList;
class ShapeLinkedListPair
{
public:
  Shape * info;
  ShapeLinkedList next;
  ShapeLinkedListPair( Shape * newInfo, ShapeLinkedList newNext )
    : info(newInfo), next( newNext )
  {
  }
};

class Picture
{ ShapeLinkedList head;
public:
  Picture()
    : head( 0 )
  {
  }
  void enter( Shape * a )
  {
    head = new ShapeLinkedListPair( a, head );
  }
  double totalArea()
  {
    double total = 0.0;
    for (ShapeLinkedList p = head; p != 0; p = p->next)
      total += p->info->area();
    return total;
  }
};

int main()
{
  Picture p;
  p.enter( new Triangle(10,10) );
  p.enter( new Square(10) );
  cout << "Total area = " << p.totalArea() << endl;
}