Class Closure

src/main/java/groovy/lang/Closure.java:76–1427

Represents any closure object in Groovy. Groovy allows instances of Closures to be called in a short form. For example: def a = 1 def c = { a } assert c() == 1 To be able to use a Closure in this way with your own subclass, you need to provide

 * </pre>
 */
public abstract class Closure<V> extends GroovyObjectSupport implements Cloneable, Runnable, GroovyCallable<V>, Serializable {

    /**
     * With this resolveStrategy set the closure will attempt to resolve property references and methods to the
     * owner first, then the delegate (<b>this is the default strategy</b>).
     *
     * For example the following code:
     * <pre class="language-groovy groovyTestCase">
     * class Test {
     *     def x = 30
     *     def y = 40
     *
     *     def run() {
     *         def data = [ x: 10, y: 20 ]
     *         def cl = { y = x + y }
     *         cl.delegate = data
     *         cl()
     *         assert x == 30
     *         assert y == 70
     *         assert data == [x:10, y:20]
     *     }
     * }
     *
     * new Test().run()
     * </pre>
     * Will succeed, because the x and y fields declared in the Test class shadow the variables in the delegate.<p>
     * <i>Note that local variables are always looked up first, independently of the resolution strategy.</i>
     */
    public static final int OWNER_FIRST = 0;

    /**
     * With this resolveStrategy set the closure will attempt to resolve property references and methods to the
     * delegate first then the owner.
     *
     * For example the following code:
     * <pre class="language-groovy groovyTestCase">
     * class Test {
     *     def x = 30
     *     def y = 40
     *
     *     def run() {
     *         def data = [ x: 10, y: 20 ]
     *         def cl = { y = x + y }
     *         cl.delegate = data
     *         cl.resolveStrategy = Closure.DELEGATE_FIRST
     *         cl()
     *         assert x == 30
     *         assert y == 40
     *         assert data == [x:10, y:30]
     *     }
     * }
     *
     * new Test().run()
     * </pre>
     * This will succeed, because the x and y variables declared in the delegate shadow the fields in the owner class.<p>
     * <i>Note that local variables are always looked up first, independently of the resolution strategy.</i>
     */
    public static final int DELEGATE_FIRST = 1;