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
015package org.apache.tapestry5.plastic;
016
017/**
018 * Defines per-instance context values for a transformed PlasticClass.
019 */
020public 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}