    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
    015    package 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     */
    023    public 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    }