/*
Wotonomy: OpenStep design patterns for pure Java applications.
Copyright (C) 2001 Intersect Software Corporation

This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public
License along with this library; if not, see http://www.gnu.org
*/

package net.wotonomy.control;

import net.wotonomy.foundation.NSSelector;

/**
 * A convenience observer for objects that do not or cannot subclass
 * EODelayedObserver. EOObserverProxy will invoke an NSSelector on an object
 * when it receives a subjectChanged message.
 *
 * @author michael@mpowers.net
 * @author $Author: cgruber $
 * @version $Revision: 893 $
 */
public class EOObserverProxy extends EODelayedObserver {
	protected Object target;
	protected NSSelector selector;
	protected int priority;

	/**
	 * Constructs an EODelayedObserver that will invoke the specified selector on
	 * the specified object, and will run at the specified priority.
	 */
	public EOObserverProxy(Object anObject, NSSelector aSelector, int aPriority) {
		target = anObject;
		selector = aSelector;
		priority = aPriority;
	}

	/**
	 * Constructs an EODelayedObserver that will invoke the specified selector on
	 * the specified object, and will run at ObserverPriorityThird priority, which
	 * is the default.
	 */
	public EOObserverProxy(Object anObject, NSSelector aSelector) {
		this(anObject, aSelector, ObserverPriorityThird);
	}

	/**
	 * Returns the priority of this observer in the queue. This implementation
	 * returns the priority specified in the constructor.
	 */
	public int priority() {
		return priority;
	}

	/**
	 * Notifies observer that one or more objects that it is observing have changed.
	 * The observer should check all objects it is observing for changes.
	 */
	public void subjectChanged() {
		try {
			selector.invoke(target);
		} catch (Exception exc) {
			System.out.println("Error notifying observer: ");
			exc.printStackTrace();
		}
	}

}

/*
 * $Log$ Revision 1.1 2006/02/16 13:19:57 cgruber Check in all sources in
 * eclipse-friendly maven-enabled packages.
 *
 * Revision 1.1 2001/10/22 21:55:32 mpowers This turns out to be a really useful
 * class.
 *
 *
 */