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}