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Groovy: A powerful, dynamic language for the JVM
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/*
 * Copyright 2008-2012 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;

import org.codehaus.groovy.transform.GroovyASTTransformationClass;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * Note: This annotation is currently experimental! Use at your own risk!
 * 
 * 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()
 *   }
 *   ...
 * }
 * 
 *
 * @author Paul King
 * @since 1.8.0
 */
@java.lang.annotation.Documented
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.TYPE})
@GroovyASTTransformationClass("org.codehaus.groovy.transform.AutoExternalizeASTTransformation")
public @interface AutoExternalize {
    /**
     * Comma separated list of property names to exclude from externalizing.
     * For convenience, a String with comma separated names
     * can be used in addition to an array (using Groovy's literal list notation) of String values.
     */
    String[] excludes() default {};

    /**
     * Include fields as well as properties when externalizing.
     */
    boolean includeFields() default false;
}