groovy.lang

Annotation Type DelegatesTo

@Documented
@Retention(value=RUNTIME)
@Target(value=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

Author:

Cedric Champeau, Peter Niderwieser

Optional Element Summary

Optional Elements

Modifier and Type	Optional Element 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

Element Detail

value

public abstract Class value

Default:

groovy.lang.DelegatesTo.Target.class

strategy

public abstract int strategy

The Closure.resolveStrategy used by the closure.

Default:

0

genericTypeIndex

public abstract 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

target

public abstract 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:

""

type

public abstract 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:

""