namespace.java

ZK 基础介绍 功能操作 模块 结合数据库操作

/* Namespace.java

{{IS_NOTE
	Purpose:
		
	Description:
		
	History:
		Mon Apr 10 15:59:29     2006, Created by tomyeh
}}IS_NOTE

Copyright (C) 2006 Potix Corporation. All Rights Reserved.

{{IS_RIGHT
	This program is distributed under GPL Version 2.0 in the hope that
	it will be useful, but WITHOUT ANY WARRANTY.
}}IS_RIGHT
*/
package org.zkoss.zk.scripting;

import java.util.Set;
import org.zkoss.zk.ui.Component;

/**
 * To represent the name space for storing variables.
 * There are two ways to declare variables: by zscirpt, or by
 * {@link org.zkoss.zk.ui.Component#setVariable}/
 * {@link org.zkoss.zk.ui.Page#setVariable}.
 *
 * <p>Each ID space ({@link org.zkoss.zk.ui.IdSpace} has an independent
 * name space to store varaibles.
 * It is a mimic concept of ID space to work with zscript.
 *
 * @author tomyeh
 * @see Interpreter
 */
public interface Namespace {
	/** Returns a set of variable names stored in this name space.
	 * <p>Note: it doesn't include the parent's varaibles.
	 */
	public Set getVariableNames();

	/** Returns whether the specified variable is defined.
	 *
	 * @param local whether not to search its ancestor.
	 * If false and the current ID space doen't define the variable,
	 * it searches up its ancestor (via {@link #getParent}) to see
	 * any of them has defined the specified variable.
	 */
	public boolean containsVariable(String name, boolean local);
	/** Returns the variable of the specified name, or null if not
	 * defined or the value is null.
	 *
	 * @param local whether not to search its ancestor.
	 * If false and the current ID space doen't define the variable,
	 * it searches up its ancestor (via {@link #getParent}) to see
	 * any of them has defined the specified variable.
	 */
	public Object getVariable(String name, boolean local);
	/** Sets the variable of the specified name.
	 * @param local whether not to set the variable to this name space
	 * directly. If false, it searches whether the variable is defined
	 * in any of its ancestor (via {@link #getParent}). If local = false
	 * and the ancestor is found, the value is stored to the ancestor
	 * instead of this.
	 * @exception org.zkoss.zk.ui.UiException if failed.
	 */
	public void setVariable(String name, Object value, boolean local);
	/** Unsets a variable from the current ID space.
	 * <p>Unlike {@link #setVariable}, this method removed only
	 * the variable defined in the ID space cotnaining this component.
	 */
	public void unsetVariable(String name, boolean local);

	/** Returns the parent name space, or null if this is topmost.
	 */
	public Namespace getParent();
	/** Sets the parent name space.
	 */
	public void setParent(Namespace parent);

	/** Adds a change listener to listen whether this namespace is changed.
	 * The listener is called when a variable is added, removed, or
	 * the parent is changed.
	 *
	 * @return wether the resolver is added successfully.
	 * Note: if the resolver was added before, it won't be added again
	 * and this method returns false.
	 */
	public boolean addChangeListener(NamespaceChangeListener listener);
	/** Removes a change listener from this namespace.
	 *
	 * @return false if resolved is not added before.
	 */
	public boolean removeChangeListener(NamespaceChangeListener listener);
}