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Groovy: A powerful, dynamic language for the JVM

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/*
 * Copyright 2008-2010 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;

/**
 * Variable annotation used for changing the scope of a variable within a script from
 * being within the run method of the script to being at the class level for the script.
 * 
 * The annotated variable will become a private field of the script class.
 * The type of the field will be the same as the type of the variable. Example usage:
 * 
 * {@code @Field} List awe = [1, 2, 3]
 * def awesum() { awe.sum() }
 * assert awesum() == 6
 * 
 * In this example, without the annotation, variable awe would be
 * a local script variable (technically speaking it will be a local variable within
 * the run method of the script class). Such a local variable would
 * not be visible inside the awesum method. With the annotation,
 * awe becomes a private List field in the script class and is
 * visible within the awesum method.
 *
 * @author Paul King
 * @since 1.8.0
 */
@java.lang.annotation.Documented
@Retention(RetentionPolicy.SOURCE)
@Target({ElementType.LOCAL_VARIABLE})
@GroovyASTTransformationClass("org.codehaus.groovy.transform.FieldASTTransformation")
public @interface Field {
}