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
015package org.apache.tapestry5.internal.transform;
016
017import 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 */
028public 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}