/* java.beans.beancontext.BeanContextChild
   Copyright (C) 1999 Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
 
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

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02111-1307 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
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As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
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terms of your choice, provided that you also meet, for each linked
independent module, the terms and conditions of the license of that
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this exception to your version of the library, but you are not
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package java.beans.beancontext;

import java.beans.PropertyChangeListener;
import java.beans.VetoableChangeListener;
import java.beans.PropertyVetoException;

/**
 * Beans implement this to get information about the execution environment and
 * its services and to be placed in the hierarchy.
 * <P>
 *
 * The difference between a <code>BeanContext</code> and a
 * <code>BeanContextChild</code>, mainly, is that a
 * <code>BeanContext</code> may be a parent.
 * <P>
 *
 * <code>BeanContextChild</code> instances will be serialized at some
 * point in their life, but you need to make sure your bean context does
 * not contain a serializable reference (directly or indirectly) to the
 * parent <code>BeanContext</code>, to any of the other
 * <code>BeanContext</code>s in the tree, or to any resources obtained
 * via the <code>BeanContextServices</code> interface.  One way to do this
 * is to mark any fields that contain such references as
 * <code>transient</code>.  Another way is to use a custom serializer.
 * <P>
 *
 * If you do not do this, when the <code>BeanContext</code> is serialized,
 * all the other <code>BeanContext</code>s and other unnecessary things
 * will be serialized along with it.
 * <P>
 *
 * Before dying, a <code>BeanContextChild</code> should call
 * <code>getBeanContext().remove(this)</code> to detach from the
 * hierarchy and exit cleanly.
 *
 * @author John Keiser
 * @since JDK1.2
 * @see java.beans.beancontext.BeanContext
 */

public interface BeanContextChild {
	/**
	 * Set the parent <code>BeanContext</code>.
	 * <P>
	 *
	 * This method is called from <code>BeanContext.add()</code> and
	 * should not be called directly.
	 * <P>
	 *
	 * When this Object is being added to a new BeanContext or moved
	 * from an old one, a non-null value will be passed in.
	 * <P>
	 *
	 * When this Object is being removed from the current
	 * <code>BeanContext</code>, <code>setBeanContext()</code> will
	 * receive the parameter <code>null</code>.
	 * <P>
	 *
	 * When being removed from the current <code>BeanContext</code>,
	 * it is the <code>BeanContextChild</code>'s responsibility to
	 * release all services it has obtained.
	 * <P>
	 *
	 * This change should generate <code>PropertyChangeEvent</code>
	 * and <code>VetoableChangeEvent</code>s with the property name
	 * "beanContext".  If the change is vetoed, it must re-throw the
	 * exception and not change anything.  In this way, the parent
	 * <code>BeanContextChild</code>, who has registered himself with
	 * you, will have a chance to remove this child from its
	 * collection.
	 * <P>
	 *
	 * If the Bean does not wish to change the parent or be removed
	 * from one, it may throw the <code>PropertyVetoException</code>.
	 * If you veto a <code>setBeanContext(null)</code> call, then you
	 * should try your hardest to remedy whatever problem is keeping
	 * you from being removed from the <code>BeanContext</code> so
	 * that you can <em>not</em> veto it the next time.
	 * Otherwise, nasty pathological recursion stuff could occur in
	 * certain situations.
	 * <P>
	 *
	 * If you do veto the change, you must first back out any changes
	 * you made prior to the veto.  Best not to make any such changes
	 * prior to the veto in the first place.
	 * <P>
	 *
	 * This method is called from <code>BeanContext.add()</code> and
	 * should not be called directly.
	 *
	 * @param parent the new parent for the <code>BeanContextChild</code>,
	 *        or <code>null</code> to signify removal from a tree.
	 * @exception PropertyVetoException if the
	 *            <code>BeanContextChild</code> implementor does not
	 *            wish to have its parent changed.
	 */
	void setBeanContext(BeanContext parent)
		throws PropertyVetoException;

	/**
	 * Get the parent <code>BeanContext</code>.
	 * @return the parent <code>BeanContext</code>.
	 */
	BeanContext getBeanContext();

	/**
	 * Add a listener that will be notified when a specific property changes.
	 * @param prop the name of the property to listen on
	 * @param listener the listener to listen on the property.
	 */
	void addPropertyChangeListener(String prop, PropertyChangeListener listener);

	/**
	 * Remove a listener to a certain property.
	 * @param prop the name of the property being listened on
	 * @param listener the listener listening on the property.
	 */
	void removePropertyChangeListener(String prop, PropertyChangeListener listener);

	/**
	 * Add a listener that will be notified when a specific property
	 * change is requested (a PropertyVetoException may be thrown) as
	 * well as after the change is successfully made.
	 *
	 * @param prop the name of the property to listen on
	 * @param listener the listener to listen on the property.
	 */
	void addVetoableChangeListener(String prop, VetoableChangeListener listener);

	/**
	 * Remove a listener to a certain property.
	 * @param prop the name of the property being listened on
	 * @param listener the listener listening on the property.
	 */
	void removeVetoableChangeListener(String prop, VetoableChangeListener listener);
}
