/* -*- Mode: Java; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- * * This file is part of the design patterns project at UBC * * The contents of this file are subject to the Mozilla Public License * Version 1.1 (the "License"); you may not use this file except in * compliance with the License. You may obtain a copy of the License at * either http://www.mozilla.org/MPL/ or http://aspectj.org/MPL/. * * Software distributed under the License is distributed on an "AS IS" basis, * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License * for the specific language governing rights and limitations under the * License. * * The Original Code is ca.ubc.cs.spl.patterns. * * Contributor(s): */ import java.awt.Color; /** * Concretizes the observing relationship for Point (subject) * and Screen (observer). Color changes trigger updates. * * @author Gregor Kiczales * @author Jan Hannemann * @version 1.0, 05/13/02 * */ public aspect ColorObserver extends ObserverProtocol{ /** * Assings the Subject role to the Point class. * Roles are modeled as (empty) interfaces. */ declare parents: Point implements Subject; /** * Assings the Observer role to the Screen class. * Roles are modeled as (empty) interfaces. */ declare parents: Screen implements Observer; /** * Specifies the joinpoints that constitute a change to the * Subject. Captures calls to Point.setColor(Color) * . * * @param s the Point acting as Subject */ protected pointcut subjectChange(Subject s): call(void Point.setColor(Color)) && target(s); /** * Defines how each Observer is to be updated when a change * to a Subject occurs. * * @param s the subject on which a change of interest occured * @param o the observer to be notifed of the change */ protected void updateObserver(Subject s, Observer o) { ((Screen)o).display("Screen updated because color changed."); } }