// outline of using observer pattern for the goblins program.

superclass player

class human : player   (also apply singleton pattern)
class goblin1 : player
class goblin2 : player
class treasure : player

---------

independent hierarchy:  goblins are observers, human is observee or (subject)

// Abstract interfaces


interface observee   // abstract subject
{
  void attach(observer A);
  void detach(observer A);
  void notify();
}

interface observer
{
  void update(observee B);
}

class human : player, observee
class goblin1 : player, observer
class goblin2 : player, observer
class treasure : player, observer


class human:  player, observee
{
   ArrayList obsvs = new arraylist; // list of observers
   public void attach(observer A) { obsvs.Add(A); }
   public void detach(observer A) { obsvs.Remove(A); }
   public void notify()
    { foreach (observer B in obsvs) { B.update(this); } }

   public void setdirection(int newdx, int newdy)
    {  
	dx = newdx;
	dy = newdy;
	notify();
    }
}


class goblin1 : player, observer
{
   public void update(observee B)
   {
      human prof = (human)B;
      // change movement vector to try to catch B accordingly
      //B.dx, B.dy - not available before typecast.
   }

   
}