001    // Copyright 2004, 2005 The Apache Software Foundation
002    //
003    // Licensed under the Apache License, Version 2.0 (the "License");
004    // you may not use this file except in compliance with the License.
005    // You may obtain a copy of the License at
006    //
007    //     http://www.apache.org/licenses/LICENSE-2.0
008    //
009    // Unless required by applicable law or agreed to in writing, software
010    // distributed under the License is distributed on an "AS IS" BASIS,
011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012    // See the License for the specific language governing permissions and
013    // limitations under the License.
014    
015    package org.apache.tapestry.util;
016    
017    import java.util.List;
018    
019    /**
020     *  An interface that defines an object that can store named propertys.  The names
021     *  and the properties are Strings.
022     *
023     *  @author Howard Lewis Ship
024     *
025     **/
026    
027    public interface IPropertyHolder
028    {
029        /**
030         *  Returns a List of Strings, the names of all
031         *  properties held by the receiver.  May return an empty list.
032         *  The List is sorted alphabetically.  The List may be modified
033         *  without affecting this property holder.
034         *
035         *  <p>Prior to release 2.2, this method returned Collection.
036         * 
037         **/
038    
039        public List getPropertyNames();
040    
041        /**
042         *  Sets a named property.  The new value replaces the existing value, if any.
043         *  Setting a property to null is the same as removing the property.
044         *
045         **/
046    
047        public void setProperty(String name, String value);
048    
049        /**
050         *  Removes the named property, if present.
051         *
052         **/
053    
054        public void removeProperty(String name);
055    
056        /**
057         *  Retrieves the named property, or null if the property is not defined.
058         *
059         **/
060    
061        public String getProperty(String name);
062    }