001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018 package org.apache.commons.jexl2.introspection;
019
020 /**
021 * Interface used for setting values that appear to be properties.
022 * Ex.
023 * <code>
024 * ${foo.bar = "hello"}
025 * </code>
026 * @since 1.0
027 * @author <a href="mailto:geirm@optonline.net">Geir Magnusson Jr.</a>
028 * @version $Id: JexlPropertySet.java 889760 2009-12-11 18:42:49Z sebb $
029 */
030 public interface JexlPropertySet {
031 /**
032 * Method used to set the property value of an object.
033 *
034 * @param obj Object on which the property setter will be called with the value
035 * @param arg value to be set
036 * @return the value returned from the set operation (impl specific)
037 * @throws Exception on any error.
038 */
039 Object invoke(Object obj, Object arg) throws Exception;
040
041 /**
042 * Attempts to reuse this JexlPropertySet, checking that it is compatible with
043 * the actual set of arguments.
044 * @param obj the object to invoke the the get upon
045 * @param key the property key to get
046 * @param value the property value to set
047 * @return the result of the method invocation that should be checked by tryFailed to determine if it succeeded
048 * or failed.
049 */
050 Object tryInvoke(Object obj, Object key, Object value);
051
052 /**
053 * Checks whether a tryInvoke failed or not.
054 * @param rval the value returned by tryInvoke
055 * @return true if tryInvoke failed, false otherwise
056 */
057 boolean tryFailed(Object rval);
058
059 /**
060 * Specifies if this JexlPropertySet is cacheable and able to be reused for
061 * this class of object it was returned for.
062 *
063 * @return true if can be reused for this class, false if not
064 */
065 boolean isCacheable();
066 }