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 * Allows read/write access directly to a field (bypassing accessors). Does not use reflection, even
019 * if the field is private (the normal case for Plastic classes).
020 */
021public interface FieldHandle
022{
023    /**
024     * Gets the current value of the field. If the field is a primitive value, then the primitive
025     * will be wrapped.
026     * 
027     * @throws NullPointerException
028     *             if the instance is null
029     * @throws ClassCastException
030     *             if the instance is not the type that contains the field
031     */
032    Object get(Object instance);
033
034    /**
035     * Updates the current value of the field. If the field is a primitive value, then the newValue
036     * will be unwrapped automatically.
037     * 
038     * @throws NullPointerException
039     *             if the instance is null
040     * @throws NullPointerException
041     *             if the newValue is null and the field is a primitive type
042     * @throws ClassCastException
043     *             if the instance is not the type that contains the field
044     * @throws ClassCastException
045     *             if the newValue is not assignable to the field type (or not the matching wrapper type
046     *             for a primitive field)
047     */
048    void set(Object instance, Object newValue);
049}