RE: [Isugamedev-midworld] still stuck on queue

[Ben S. <bs...@vr...>]

On Mon, 17 Jun 2002, Brown Joshua L wrote:

> 
> >What if you did an observer pattern? Your object that creates the 5 other 
> >objects can register itself as listeners to those 5 objects. When each of 
> >the 5 objects generates somethings that needs to be added to the queue it 
> >could fire off an event to all listeners. In this case, the listener would 
> >be the object with the queue which would handle the event and add the 
> >object to the queue.
> 
> Basically what I really need to do is have each of the 5 sub-objects own a
> handle to their parent class that get's created when they are instantiated -
> that way I can access the public methods of the parent class.  Is that how
> the observer model works?

Umm ... yeah. Here's an example...

// Registers self with subject and waits for it to invoke objectCreated.
class Observer
   : public ObjectCreationListener
{
public:
   Observer()
   {
      Subject* sub = new Subject();
      sub->addObjectCreationListener(this);
      sub->doThatSexyThingYouDo();
   }

   void objectCreated(MyObject* obj)
   {
      // do something with obj
   }
};

// Creates objects and notifies listeners when they are created.
class Subject
{
public:
   void addObjectCreationListener(ObjectCreationListener* l)
   {
      listeners.push_back(l);
   }

   void myFunc()
   {
      // hey ... we need to create an object
      MyObject* obj = new MyObject();

      listeners::iterator itr = listeners.begin();
      while (itr != listeners.end())
      {
         (*itr)->objectCreated(obj);
      }
   }

private:
   std::vector<ObjectCreationListener*> listeners;
};

cheers,
-----
Ben Scott
Research Assistant VRAC
bs...@ia...