    001// Copyright 2010 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.services;
    016
    017/**
    018 * Captures the result of invoking a method.
    019 *
    020 * @since 5.2.0
    021 */
    022public interface MethodInvocationResult
    023{
    024    /**
    025     * The return value from the method invocation. This will be null if the method returns null,
    026     * is a void method, or if a checked exception was thrown by the method.
    027     */
    028    Object getReturnValue();
    029
    030    /**
    031     * If true, then the method invocation ended with a checked exception being thrown.
    032     */
    033    boolean isFail();
    034
    035    /**
    036     * If the invocation threw a checked exception, this method will wrap that exception in a
    037     * RuntimeException and throw that. For most code that doesn't specifically care about
    038     * the thrown exception, this method should be invoked before continuing on to
    039     * examine {@link #getReturnValue()}.
    040     */
    041    void rethrow();
    042
    043    /**
    044     * If {@link #isFail()} is true, this method provides access to the actual checked exception that was thrown.
    045     *
    046     * @param throwableClass
    047     *            the type of exception to match
    048     * @return the exception, if the method invocation threw a checked exception, and the exception is assignable to
    049     *         the provided type. In other cases, null is returned.
    050     */
    051    <T extends Throwable> T getThrown(Class<T> throwableClass);
    052}