source: trunk/src_apollo/org/apollo/mvc/Observer.java@ 315

package org.apollo.mvc;

/**
 * An Observer as any object that would like to be notified
 * when another object changes. To do this the object that will change
 * must implement the Subject interface and then the Observer object
 * should be registered with the Subject by calling addObserver()
 * 
 * @author Brook NOvak
 */
public interface Observer {
        
        /**
         * The method called when a Subject that this observer has
         * registered with changes and the Subject has specified a SubjectChangedEvent.
         * 
         * @param event A type of SubjectChangedEvent
         * @param source The subject which the event was fired from
         */
        void modelChanged(Subject source, SubjectChangedEvent event);
        
        /**
         * Informs this observer what it is observing.
         * The subject will call this automatically.
         * The observer must know what it's observing so that
         * it can update based on the subject's data.
         * 
         * @param parent the subject we are observing
         */
        void setObservedSubject(Subject parent);

        /**
         * Provides functionality to retrieve the subject that this class
         * will be observing.
         * 
         * @return the subject we are observing
         */
        Subject getObservedSubject();
        
}