groovy.lang.DelegatesTo Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.lang;
import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
/**
* This annotation can be used by API or DSL writers to document parameters which accept a closure.
* In that case, using this annotation, you can specify what the delegate type of the closure will
* be. This is important for IDE support.
*
* This annotation can also be used to help the type checker ({@link groovy.transform.TypeChecked})
* which would not report errors then if the delegate is of the documented type. Of course, it is
* also compatible with {@link groovy.transform.CompileStatic}.
*
* Example:
*
* // Document the fact that the delegate of the closure will be an ExecSpec
* ExecResult exec(@DelegatesTo(ExecSpec) Closure closure) { ... }
*
*
* @author Cedric Champeau
* @author Peter Niderwieser
* @since 2.1.0
*/
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.PARAMETER})
public @interface DelegatesTo {
Class value() default Target.class;
/**
* The {@link Closure#resolveStrategy} used by the closure.
*/
int strategy() default Closure.OWNER_FIRST;
/**
* The index of the generic type that will be the type of the closure's delegate.
* The generic types are considered with respect to the {@code @DelegatesTo.Target} annotated
* parameter for this usage, with the index starting at 0.
*/
int genericTypeIndex() default -1;
/**
* In cases when there are multiple {@code @DelegatesTo.Target} annotated parameters, this
* member should be set to the {@link DelegatesTo.Target#value()} of the correct target.
*/
String target() default "";
/**
* The type member should be used when the type of the delegate cannot
* be represented with {@link #value()}, {@link #genericTypeIndex()} or
* {@link #target()}. In this case, it is possible to use a String to represent
* the type, at the cost of potential uncaught errors at compile time if the
* type is invalid and increased compile time.
*
* @return a String representation of a type
* @since 2.4.0
*/
String type() default "";
/**
* Parameter annotation used to specify the delegate for a {@code @DelegatesTo} annotated
* parameter of the same method.
*/
@Retention(RetentionPolicy.RUNTIME)
@java.lang.annotation.Target({ElementType.PARAMETER})
public static @interface Target {
/**
* An identifier that should be used to disambiguate targets when there are
* multiple {@code @DelegatesTo.Target} annotated parameters.
*/
String value() default "";
}
}