    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}