/*******************************************************************************
 * Copyright (c) 2006, 2008 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/

module org.eclipse.core.databinding.observable.value.IObservableValue;

import java.lang.all;

import org.eclipse.core.databinding.observable.IObservable;
import org.eclipse.core.databinding.observable.Realm;

/**
 * A value whose changes can be tracked by value change listeners.
 * 
 * @noextend This interface is not intended to be extended by clients.
 * @noimplement This interface is not intended to be implemented by clients.
 *              Clients should instead subclass one of the classes that
 *              implement this interface. Note that direct implementers of this
 *              interface outside of the framework will be broken in future
 *              releases when methods are added to this interface.
 * 
 * @see AbstractObservableValue
 * 
 * @since 1.0
 */
public interface IObservableValue : IObservable {

    /**
     * The value type of this observable value, or <code>null</code> if this
     * observable value is untyped.
     * 
     * @return the value type, or <code>null</null>
     */
    public Object getValueType();

    /**
     * Returns the value.  Must be invoked in the {@link Realm} of the observable.
     * 
     * @return the current value
     * @TrackedGetter
     */
    public Object getValue();

    /**
     * Sets the value.  Must be invoked in the {@link Realm} of the observable.
     * 
     * @param value
     *            the value to set
     * @throws UnsupportedOperationException
     *             if this observable value cannot be set.
     */
    public void setValue(Object value);

    /**
     * 
     * @param listener
     */
    public void addValueChangeListener(IValueChangeListener listener);

    /**
     * @param listener
     */
    public void removeValueChangeListener(IValueChangeListener listener);
}