tapestry/tapestry-framework/src/java/org/apache/tapestry/engine/IPropertySource.java

// Copyright 2004, 2005 The Apache Software Foundation
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package org.apache.tapestry.engine;

/**
 * A source for configuration properties.
 * 
 * @author Howard Lewis Ship
 * @since 2.3
 */

public interface IPropertySource
{

    /**
     * Returns the value for a given property, or null if the source does not
     * provide a value for the named property. Implementations of
     * IPropertySource may use delegation to resolve the value (that is, if one
     * property source returns null, it may forward the request to another
     * source).
     *
     * @param propertyName
     *          Name of the property to get.
     * 
     * @return Value of property or null if none found.
     */

    String getPropertyValue(String propertyName);
}