/// <summary>
/// A MallardDuck uses the Quack class to handle its Quack,
/// so when PerformQuack is called, the responsibility for
/// the Quack is delegated to the Quack object and we get a real Quack.
/// And it uses FlyWithWings as its IFlyBehavior.
/// </summary>
public MallardDuck()
{
// These two instance variables are inherited from the Duck superclass.
quackBehavior = new Quacks();
flyBehavior = new FlyWithWings();
}
/// <summary>
/// Model duck subclass
/// </summary>
public ModelDuck()
{
// The model duck begins like grounded without a way to fly.
flyBehavior = new FlyNoWay();
quackBehavior = new Quacks();
}