static void Main(string[] args)
{
Asteroid a = new Asteroid();
ExplodingAsteroid ea = new ExplodingAsteroid();
SpaceShip s = new SpaceShip();
TieFighter tf = new TieFighter();
a.CollideWith(s);
a.CollideWith(tf);
ea.CollideWith(s);
ea.CollideWith(tf);
Console.WriteLine();
a = ea;
s = tf;
a.CollideWith(s);
}
public override void CollideWith(SpaceShip s)
{
s.CollideWith(this);
}
public virtual void CollideWith(SpaceShip s)
{
s.CollideWith(this);
}