001    // Copyright 2011, 2012 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    
015    package org.apache.tapestry5.plastic;
016    
017    /**
018     * Allows a listener to be notified about classes about to be loaded by the manager's class loader.
019     * Some classes are loaded by the same class loader but not transformed (for example, inner classes). These
020     * do not generate events. In many cases, transforming a class will cause supporting classes (representing
021     * {@link MethodInvocation}s, and other things) to be created; these do generate events, and can be distinguished
022     * by the {@linkplain PlasticClassEvent#getType() event's type property}.
023     * 
024     * @see PlasticClassListenerHub
025     */
026    public interface PlasticClassListener
027    {
028        /**
029         * Invoked just before a class is to be loaded. Separate events are fired for supporting classes before
030         * the event for the primary class (the class being transformed or created from scratch).
031         * 
032         * @param event
033         *            describes the class to be loaded, and gives access to its disassembled
034         *            bytecode (for debugging purposes)
035         */
036        void classWillLoad(PlasticClassEvent event);
037    }