001    // Copyright 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    
015    package org.apache.tapestry5.plastic;
016    
017    /**
018     * Defines per-instance context values for a transformed PlasticClass.
019     */
020    public interface InstanceContext
021    {
022        /**
023         * Returns the type of the instance created with this context. This is most often of interest
024         * to implementations of {@link ComputedValue}.
025         */
026        Class<?> getInstanceType();
027    
028        /**
029         * Gets an instance context value which is identified by type.
030         * 
031         * @throws IllegalArgumentException
032         *             if no such value is available in the context.
033         */
034        <T> T get(Class<T> valueType);
035    }