/* -*- 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.");
}
}