org.apache.commons.jexl.util.introspection.VelPropertyGet Maven / Gradle / Ivy

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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.commons.jexl.util.introspection;

/**
 * Interface defining a 'getter'. For uses when looking for resolution of
 * property references
 *
 * $foo.bar
 *
 * @since 1.0
 * @author Geir Magnusson Jr.
 * @version $Id: VelPropertyGet.java 584050 2007-10-12 05:27:50Z proyal $
 */
public interface VelPropertyGet {
    /**
     * invocation method - called when the 'get action' should be performed and
     * a value returned.
     * @param o the object to get the property from.
     * @return the property value.
     * @throws Exception on any error.
     */
    Object invoke(Object o) throws Exception;

    /**
     * specifies if this VelPropertyGet is cacheable and able to be reused for
     * this class of object it was returned for.
     *
     * @return true if can be reused for this class, false if not
     */
    boolean isCacheable();

    /**
     * returns the method name used to return this 'property'.
     * @return the method name.
     */
    String getMethodName();

    /**
     * Tell whether the method underlying this 'property' is alive by
     * checking to see if represents a successful name resolution.
     *
     * @return boolean Whether 'property' is alive.
     */
    boolean isAlive();
}