groovy.transform.AutoExternalize.groovy Maven / Gradle / Ivy

/*
 * Copyright 2003-2014 the original author or authors.
 *
 * Licensed 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 groovy.transform;

/**
 * Class annotation used to assist in the creation of {@code Externalizable} classes.
 * The {@code @AutoExternalize} annotation instructs the compiler to execute an
 * AST transformation which adds {@code writeExternal()} and {@code readExternal()} methods
 * to a class and adds {@code Externalizable} to the interfaces which the class implements.
 * The {@code writeExternal()} method writes each property (or field) for the class while the
 * {@code readExternal()} method will read each one back in the same order. Properties or fields
 * marked as {@code transient} are ignored.
 * 
 * Example usage:
 * 
 * import groovy.transform.*
 * {@code @AutoExternalize}
 * class Person {
 *   String first, last
 *   List favItems
 *   Date since
 * }
 * 
 * Which will create a class of the following form:
 *  * class Person implements Externalizable {
 *   ...
 *   public void writeExternal(ObjectOutput out) throws IOException {
 *     out.writeObject(first)
 *     out.writeObject(last)
 *     out.writeObject(favItems)
 *     out.writeObject(since)
 *   }
 *
 *   public void readExternal(ObjectInput oin) {
 *     first = oin.readObject()
 *     last = oin.readObject()
 *     favItems = oin.readObject()
 *     since = oin.readObject()
 *   }
 *   ...
 * }
 * 
 * 
 * The {@code @AutoExternalize} transform is implemented as a combination of the {@code @ExternalizeMethods} and {@code @ExternalizeVerifier} transforms.
 *
 * @author Paul King
 * @since 1.8.0
 */
@AnnotationCollector([ExternalizeMethods, ExternalizeVerifier])
@interface AutoExternalize { }