// The main program

        static void Main(string[] args)
        {
            Human fred = new Human("Fred");
            Human bob = new Human("Bob");
            Ogre bill = new Ogre("Bill");

            Building castle = new Building();

            fred.SayHello();
            bill.SayHello();

            castle.AssignGuard(fred);
            castle.AssignGuard(bob);

            // Make the guards patrol
            // the castle
            castle.StartPatrol();

            // Give em lunch
            castle.LunchBreak();

            // Demo pickup a new spell
            fred.CastSpell();   // No spell
            fred.PickUpSpell(new FireballSpell());
            fred.CastSpell();

            Console.ReadLine(); // Pause
        }

// The parent class

    abstract class Character
    {
        // Attributes
        private string _name;

        // Constructors
        public Character(string name)
        {
            _name = name;
        }

        // Properties
        public string Name
        {
            get { return _name; }
            set { _name = value; }
        }

        // Methods

        // Polymorphism (i.e. virtual)
        // Allow child class (Human, Ogre, etc) to
        // provide a different method to this.
        public virtual void SayHello()
        {
            Console.WriteLine("Character {0} says hello", Name);
        }
    }

// The child classes

    // Implement ISecurityGuard so Human can play the role
    // of a Security Guard.
    class Human:Character, ISecurityGuard   // Inherit from Character
    {
        // Attributes
        private IMagicSpell _currentSpell;

        // Constructors
        public Human(string name)
            : base(name)                // Give the character a name
        {
            // Human starts off with no spell
            // to cast, until they pick one
            // up!!
            _currentSpell = new NoSpell();
        }

        // Properties

        // Methods

        public void EatDoughnuts()
        {
            Console.WriteLine("Human {0} is eating a doughnut", Name);
        }

        public void PatrolPerimeter()
        {
            Console.WriteLine("Human {0} is out on patrol", Name);
        }

        public void SearchForPlayer()
        {
            Console.WriteLine("Human {0} is searching for player", Name);
        }

        // STRATEGY DESIGN PATTERN
        // ***********************

        public void PickUpSpell(IMagicSpell spell)
        {
            // Store some Magic Spell we were
            // just passed
            _currentSpell = spell;
        }

        public void CastSpell()
        {
            // I have no idea what the spell was
            // as long as the object that was passed
            // in PickUpSpell() played the role of
            // a Magic Spell I don't care!!
            _currentSpell.CastSpell();
        }
    }


    class Ogre:Character
    {
        // Attributes

        // Constructors
        public Ogre(string name)
            : base(name)                // Give the character a name
        {
        }

        // Properties

        // Methods

        // Change the way the Ogre says Hello
        // Replace the SayHello() method
        // in the parent Character class.
        public override void SayHello()
        {
            Console.WriteLine("Ogre {0} says Hdjksdfakl!!", Name);
        }
    }

// The interface -- the role of Security Guard

    interface ISecurityGuard        // Actions reqd to play the role of a Security Guard
    {
        void EatDoughnuts();
        void PatrolPerimeter();
        void SearchForPlayer();
    }

// The building using the security guard

    class Building
    {
        // Attributes
        private List<ISecurityGuard> _guards;

        // Constructors
        public Building()
        {
            _guards = new List<ISecurityGuard>();
        }

        // Properties

        // Methods

        public void AssignGuard(ISecurityGuard guard)
        {
            _guards.Add(guard);
        }

        public void StartPatrol()
        {
            foreach (ISecurityGuard guard in _guards)
            {
                guard.PatrolPerimeter();
            }
        }

        public void LunchBreak()
        {
            foreach (ISecurityGuard guard in _guards)
            {
                guard.EatDoughnuts();
            }
        }

    }

// The Magic Spell interface -- all spells must play the role of a MagicSpell

    interface IMagicSpell
    {
        void CastSpell();
    }

// Some spells

    class NoSpell:IMagicSpell
    {
        public void CastSpell()
        {
            Console.WriteLine("I don't have a spell to cast");
        }
    }

    class FireballSpell:IMagicSpell
    {
        public void CastSpell()
        {
            Console.WriteLine("Cast fireball spell");
        }
    }