scala.annotation.meta
When defining a field, the Scala compiler creates up to four accessors
for it: a getter, a setter, and if the field is annotated with
@BeanProperty, a bean getter and a bean setter.
For instance in the following class definition
class C(@myAnnot @BeanProperty var c: Int)there are six entities which can carry the annotation @myAnnot: the
constructor parameter, the generated field and the four accessors.
By default, annotations on (val-, var- or plain) constructor parameters
end up on the parameter, not on any other entity. Annotations on fields
by default only end up on the field.
The meta-annotations in package scala.annotation.meta are used
to control where annotations on fields and class parameters are copied.
This is done by annotating either the annotation type or the annotation
class with one or several of the meta-annotations in this package.
Annotating the annotation type
The target meta-annotations can be put on the annotation type when
instantiating the annotation. In the following example, the annotation
@Id will be added only to the bean getter getX.
import javax.persistence.Id
class A {
@(Id @beanGetter) @BeanProperty val x = 0
}In order to annotate the field as well, the meta-annotation @field
would need to be added.
The syntax can be improved using a type alias:
object ScalaJPA {
type Id = javax.persistence.Id @beanGetter
}
import ScalaJPA.Id
class A {
@Id @BeanProperty val x = 0
}Annotating the annotation class
For annotations defined in Scala, a default target can be specified in the annotation class itself, for example
@getter
class myAnnotation extends AnnotationThis only changes the default target for the annotation myAnnotation.
When instantiating the annotation, the target can still be specified
as described in the last section.
Type members
Classlikes
Consult the documentation in package scala.annotation.meta.
Consult the documentation in package scala.annotation.meta.
- Source:
- beanGetter.scala
Consult the documentation in package scala.annotation.meta.
Consult the documentation in package scala.annotation.meta.
- Source:
- beanSetter.scala
When defining an implicit class, the Scala compiler creates an implicit conversion method for it.
When defining an implicit class, the Scala compiler creates an implicit
conversion method for it. Annotations @companionClass and @companionMethod
control where an annotation on the implicit class will go. By default, annotations
on an implicit class end up only on the class.
- Source:
- companionClass.scala
When defining an implicit class, the Scala compiler creates an implicit conversion method for it.
When defining an implicit class, the Scala compiler creates an implicit
conversion method for it. Annotations @companionClass and @companionMethod
control where an annotation on the implicit class will go. By default, annotations
on an implicit class end up only on the class.
- Source:
- companionMethod.scala
Currently unused; intended as an annotation target for classes such as case classes that automatically generate a companion object
Currently unused; intended as an annotation target for classes such as case classes that automatically generate a companion object
- Source:
- companionObject.scala
Consult the documentation in package scala.annotation.meta.
Consult the documentation in package scala.annotation.meta.
- Source:
- field.scala
Consult the documentation in package scala.annotation.meta.
Consult the documentation in package scala.annotation.meta.
- Source:
- getter.scala
An annotation giving particulars for a language feature in object scala.language.
An annotation giving particulars for a language feature in object scala.language.
- Source:
- languageFeature.scala
Consult the documentation in package scala.annotation.meta.
Consult the documentation in package scala.annotation.meta.
- Source:
- param.scala
Consult the documentation in package scala.annotation.meta.
Consult the documentation in package scala.annotation.meta.
- Source:
- setter.scala