001    // Copyright 2010, 2011 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.tapestry5.internal.transform;
016    
017    import org.apache.tapestry5.runtime.ComponentEvent;
018    
019    /**
020     * Supplies one parameter value when invoking a component event handler method. In general,
021     * this involves extracting a value form the event's context and coercing it to a type
022     * appropriate to the parameter.
023     * <p/>
024     * These values are accumulated and used to invoke the event handler method.
025     *
026     * @since 5.2.0
027     */
028    public interface EventHandlerMethodParameterProvider
029    {
030        /**
031         * Extract the value and coerce it to the correct type.
032         *
033         * @return value that can be passed as a method parameter
034         */
035        Object valueForEventHandlerMethodParameter(ComponentEvent event);
036    }