[Java] Annotation Type DelegatesTo

  • groovy.lang.DelegatesTo 
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.PARAMETER})
public @interface DelegatesTo

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 (TypeChecked) which would not report errors then if the delegate is of the documented type. Of course, it is also compatible with CompileStatic.

Example: 

 // Document the fact that the delegate of the closure will be an ExecSpec
 ExecResult exec(@DelegatesTo(ExecSpec) Closure closure) { ... }
Since:
2.1.0

Nested Class Summary

Nested classes
Modifiers Name Description
@interface DelegatesTo.Target Parameter annotation used to specify the delegate for a @DelegatesTo annotated parameter of the same method.

Element Summary

Optional Element Summary
Type Name and Description
int genericTypeIndex
The index of the generic type that will be the type of the closure's delegate.
int strategy
The Closure.resolveStrategy used by the closure.
String target
In cases when there are multiple @DelegatesTo.Target annotated parameters, this member should be set to the DelegatesTo.Target#value() of the correct target.
String type
The type member should be used when the type of the delegate cannot be represented with value(), genericTypeIndex() or target().
Class value
Default:
Target.class

Inherited Methods Summary

Inherited Methods
Methods inherited from class Name
class Object wait, wait, wait, equals, toString, hashCode, getClass, notify, notifyAll

Element Detail

public int genericTypeIndex

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 @DelegatesTo.Target annotated parameter for this usage, with the index starting at 0.

Default:
-1

public int strategy

The Closure.resolveStrategy used by the closure.

Default:
Closure.OWNER_FIRST

public String target

In cases when there are multiple @DelegatesTo.Target annotated parameters, this member should be set to the DelegatesTo.Target#value() of the correct target.

Default:
""

public String type

The type member should be used when the type of the delegate cannot be represented with value(), genericTypeIndex() or 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.

Returns:
a String representation of a type
Since:
2.4.0
Default:
""

public Class value

Default:
Target.class

© 2003-2020 The Apache Software Foundation
Licensed under the Apache license.
https://docs.groovy-lang.org/3.0.7/html/gapi/groovy/lang/DelegatesTo.html