001    /*
002     * Copyright 2002-2004 the original author or authors.
003     *
004     * Licensed under the Apache License, Version 2.0 (the "License"); you may not
005     * use this file except in compliance with the License. You may obtain a copy of
006     * the License at
007     *
008     * http://www.apache.org/licenses/LICENSE-2.0
009     *
010     * Unless required by applicable law or agreed to in writing, software
011     * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
012     * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
013     * License for the specific language governing permissions and limitations under
014     * the License.
015     */
016    package org.springframework.rules.closure.support;
017    
018    /**
019     * Convenient super class for closures that encapsulate a block of executable
020     * code. Subclasses should override <code>void handle(Object)</code> for
021     * executing a block of code without a result.
022     *
023     * @author Keith Donald
024     */
025    public abstract class Block extends AbstractClosure {
026    
027            /**
028             * {@inheritDoc}
029             *
030             * @return allways <code>null</code>, only code is executed.
031             */
032            public final Object call(Object argument) {
033                    handle(argument);
034                    return null;
035            }
036    
037            /**
038             * Method to override in block subclasses that return no result: this method
039             * is intended encapsulate the block's processing.
040             *
041             * @param argument the argument to process
042             */
043            protected abstract void handle(Object argument);
044    
045    }