001    package org.apache.commons.digester3.plugins;
002    
003    /*
004     * Licensed to the Apache Software Foundation (ASF) under one
005     * or more contributor license agreements.  See the NOTICE file
006     * distributed with this work for additional information
007     * regarding copyright ownership.  The ASF licenses this file
008     * to you under the Apache License, Version 2.0 (the
009     * "License"); you may not use this file except in compliance
010     * with the License.  You may obtain a copy of the License at
011     *
012     *   http://www.apache.org/licenses/LICENSE-2.0
013     *
014     * Unless required by applicable law or agreed to in writing,
015     * software distributed under the License is distributed on an
016     * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
017     * KIND, either express or implied.  See the License for the
018     * specific language governing permissions and limitations
019     * under the License.
020     */
021    
022    /**
023     * Thrown when a bug is detected in the plugins code.
024     * <p>
025     * This class is intended to be used in assertion statements, similar to the way that java 1.4's native assertion
026     * mechanism is used. However there is a difference: when a java 1.4 assertion fails, an AssertionError is thrown, which
027     * is a subclass of Error; here, the PluginAssertionFailure class extends RuntimeException rather than Error.
028     * <p>
029     * This difference in design is because throwing Error objects is not good in a container-based architecture.
030     * <p>
031     * Example:
032     * 
033     * <pre>
034     * if ( impossibleCondition )
035     * {
036     *     throw new PluginAssertionFailure( &quot;internal error: impossible condition is true&quot; );
037     * }
038     * </pre>
039     * <p>
040     * Note that PluginAssertionFailure should <i>not</i> be thrown when user input is bad, or when code external to the
041     * Digester module passes invalid parameters to a plugins method. It should be used only in checks for problems which
042     * indicate internal bugs within the plugins module.
043     * 
044     * @since 1.6
045     */
046    public class PluginAssertionFailure
047        extends RuntimeException
048    {
049    
050        private static final long serialVersionUID = 1L;
051    
052        /**
053         * Constructs a new exception with the specified cause.
054         *
055         * @param cause underlying exception that caused this to be thrown
056         */
057        public PluginAssertionFailure( Throwable cause )
058        {
059            super( cause );
060        }
061    
062        /**
063         * Constructs a new exception with the specified detail message.
064         *
065         * @param msg describes the reason this exception is being thrown.
066         */
067        public PluginAssertionFailure( String msg )
068        {
069            super( msg );
070        }
071    
072        /**
073         * Constructs a new exception with the specified detail message and cause.
074         *
075         * @param msg describes the reason this exception is being thrown.
076         * @param cause underlying exception that caused this to be thrown
077         */
078        public PluginAssertionFailure( String msg, Throwable cause )
079        {
080            super( msg, cause );
081        }
082    
083    }