package org.eclipse.epf.common.preferences;

/**
 * wrapper interface for property change event
 * 
 * @author Jinhua Xi
 * @since 1.5
 *
 */
public interface IPropertyChangeEventWrapper {

	   /**
     * Returns the new value of the property.
     *
     * @return the new value, or <code>null</code> if not known
     *  or not relevant (for instance if the property was removed).
     */
    public Object getNewValue();

    /**
     * Returns the old value of the property.
     *
     * @return the old value, or <code>null</code> if not known
     *  or not relevant (for instance if the property was just
     *  added and there was no old value).
     */
    public Object getOldValue();

    /**
     * Returns the name of the property that changed.
     * <p>
     * Warning: there is no guarantee that the property name returned
     * is a constant string.  Callers must compare property names using
     * equals, not ==.
     * </p>
     *
     * @return the name of the property that changed
     */
    public String getProperty();
}