001        package com.croftsoft.core.sim;
002    
003        /***********************************************************************
004        * A simulation object updated in separate access and mutate phases.
005        * 
006        * Each loop of the simulation is started with an access (read) phase and
007        * then followed by a mutate (write) phase.
008        * During the access phase, simulation objects access the state of other
009        * simulation objects to determine how their state will change during the
010        * mutate phase.  The state of simulation objects does not change during
011        * the access phase.
012        * During the mutate phase, the simulation objects change state.  The
013        * state of simulation objects is not accessed by other simulation
014        * objects during the mutate phase.
015        * Dividing the state update into two phases ensures that the result of
016        * the update is not dependent on the order in which the simulation
017        * objects are updated.  For this to hold, the access method of every
018        * simulation object must be called at the beginning of the simulation
019        * loop before the mutate method is called on any one of the simulation
020        * objects. 
021        * 
022        * @version
023        *   $Id: Sim.java,v 1.1 2008/07/25 22:54:58 croft Exp $
024        * @since
025        *   2008-07-25
026        * @author
027        *   <a href="http://www.CroftSoft.com/">David Wallace Croft</a>
028        ***********************************************************************/
029    
030        public interface  Sim
031        ////////////////////////////////////////////////////////////////////////
032        ////////////////////////////////////////////////////////////////////////
033        {
034          
035        void  access ( );
036        
037        void  mutate ( );
038        
039        ////////////////////////////////////////////////////////////////////////
040        ////////////////////////////////////////////////////////////////////////
041        }