001// Copyright 2010 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.services;
016
017/**
018 * Used when accessing the private instance variables of a component instance.
019 * 
020 * @see TransformField#getAccess()
021 * @since 5.2.0
022 */
023public interface FieldAccess
024{
025    /**
026     * Reads the value of the field of the provided instance.
027     * 
028     * @param instance
029     *            object containing field to read
030     */
031    Object read(Object instance);
032
033    /**
034     * Updates the value of the field within the instance.
035     * 
036     * @param instance
037     *            object containing field to update
038     * @param value
039     *            new value for field
040     */
041    void write(Object instance, Object value);
042}