The SBJ MVC Framework - The Model, from Abstraction to Realization

//------------------------------------------------------------------------------
// $Workfile: MessageHandler.h $
// $Header:  $
//
//	Copyright � 2008 SbjCat
// All rights reserved.
//
//
// *** Authors ***
//	 Steve Johnson
//
// $Revision: $
//
//-----------------------------------------------------------------------------

#pragma once


namespace SbjCore
{
	namespace Mvc
	{
		
		class Controller;
		
		struct MessageHandlerImpl;
		
		/** 
		MessageHandler is the base class for Windows message handler 
		classes used in the Mvc framework. A Controller class adds an
		instance of a MessageHandler to its map of handlers keyed by 
		the message ID(s) they handle. Implementation of the actual 
		handling of messages is left for derived classes.

		In addition to providing a common base for the derived classes, 
		MessageHandler also maintains a link to any previous handler for
		its message ID that was added to the Controller.  This allows 
		derived Controllers to access handlers that were added to their 
		base classes. The Controller handles the assignment of the
		previous handler.  This is similar to the way MFC method based
		message handlers access base class handlers.

		*/
		class AFX_EXT_CLASS MessageHandler
		{
		public:
			MessageHandler();

			virtual ~MessageHandler(); 
		
		public:
			void Initialize(Controller* pCtrlr, MessageHandler* pPrevHandler);

		Controller* GetController() const;		

		protected:
			MessageHandler* GetPrevHandler() const;

		private:
			struct MessageHandlerImpl* const m_pImpl;
		};

	}
}

//*** Modification History ***
// $Log:  $