Package com.blackbuild.klum.ast

Annotation Interface Default

@Target({FIELD,METHOD}) @Retention(RUNTIME) @WriteAccess @Documented public @interface Default

Designates a default value for the given field. This automatically sets the field to that default value when the value of the annotated field is empty (null or empty collection/map) during the default lifecycle phase.

The default target as decided by the members must be exactly one of:

  • field: the value of the field with the given name
  • delegate: the value of an identically named field of the given delegate field. This is especially useful in with the Owner annotation to create composite like tree structures.
  • closure: execute the closure (in the context of this) and use the result

 given:
 @DSL
 class Container {
   String name
   Element element
 }

 @DSL
 class Element {
   @Owner Container owner

   @Default(delegate = 'owner')
   String name
 }

 when: "No name is set for the inner element"
 instance = Container.Create.With {
 name "outer"
   element {}
 }

 then: "the name of the outer instance is used"
 instance.element.name == "outer"

 when:
 instance = Container.Create.With {
   name "outer"
   element {
     name "inner"
   }
 }

 then:
 instance.element.name == "inner"
 }

Like all lifecycle annotations, this annotation can also be placed on a method, which will be executed in the phase, or on a field of type closure, which will be executed along with annotated methods.

  • Optional Element Summary

    Optional Elements
    Modifier and Type
    Optional Element
    Description
    Class<? extends groovy.lang.Closure<Object>>
    code
    Delegates to the given closure, if the annotated field is empty.
    String
    delegate
    Delegate to a field with the same name on the targeted field, if the annotated field is empty
    String
    field
    Delegates to the field with the given name, if the annotated field is empty.

  • Element Details

    • field

      String field

      Delegates to the field with the given name, if the annotated field is empty.

      @Default(field = 'other') String aValue

      leads to

      aValue ?: other
      Default:
      ""

    • code

      Class<? extends groovy.lang.Closure<Object>> code

      Delegates to the given closure, if the annotated field is empty.

      @Default(code = { name.toLowerCase() }) String aValue

      leads to

      aValue ?: name.toLowerCase()
      Default:
      com.blackbuild.klum.ast.NoClosure.class

    • delegate

      String delegate

      Delegate to a field with the same name on the targeted field, if the annotated field is empty

      @Default(delegate = 'other') String aValue

      leads to

      aValue ?: parent.aValue
      Default:
      ""