Packages

t

scala.reflect.api

Annotations

trait Annotations extends AnyRef

EXPERIMENTAL

This trait provides annotation support for the reflection API.

In Scala, annotations belong to one of the two categories:

  • Java annotations: annotations on definitions produced by the Java compiler, i.e., subtypes of java.lang.annotation.Annotation attached to program definitions. When read by Scala reflection, the scala.annotation.ClassfileAnnotation trait is automatically added as a superclass to every Java annotation type.
  • Scala annotations: annotations on definitions or types produced by the Scala compiler.

When a Scala annotation that inherits from scala.annotation.StaticAnnotation or scala.annotation.ClassfileAnnotation is compiled, it is stored as special attributes in the corresponding classfile, and not as a Java annotation. Note that subclassing just scala.annotation.Annotation is not enough to have the corresponding metadata persisted for runtime reflection.

Both Java and Scala annotations are represented as typed trees carrying constructor invocations corresponding to the annotation. For instance, the annotation in @ann(1, 2) class C is represented as q"@new ann(1, 2)".

Unlike Java reflection, Scala reflection does not support evaluation of constructor invocations stored in annotations into underlying objects. For instance it's impossible to go from @ann(1, 2) class C to ann(1, 2), so one has to analyze trees representing annotation arguments to manually extract corresponding values. Towards that end, arguments of an annotation can be obtained via annotation.tree.children.tail.

For more information about Annotations, see the Reflection Guide: Annotations, Names, Scopes, and More

Self Type
Universe
Source
Annotations.scala
Linear Supertypes
AnyRef, Any
Known Subclasses
JavaUniverse, Universe, Universe
Type Hierarchy
Content Hierarchy
Universe.LiteralArgumentUniverse.ArrayArgumentUniverse.NestedArgumentUniverse.JavaArgument
Ordering
  1. Grouped
  2. Alphabetic
  3. By Inheritance
Inherited
  1. Annotations
  2. AnyRef
  3. Any
Implicitly
  1. by any2stringadd
  2. by StringFormat
  3. by Ensuring
  4. by ArrowAssoc
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Visibility
  1. Public
  2. All

Type Members

  1. abstract type Annotation >: Null <: Universe.AnnotationApi

    Information about an annotation.

  2. trait AnnotationApi extends AnyRef

    The API of Annotation instances.

    The API of Annotation instances. The main source of information about annotations is the scala.reflect.api.Annotations page.

  3. abstract class AnnotationExtractor extends AnyRef

    An extractor class to create and pattern match with syntax Annotation(tpe, scalaArgs, javaArgs).

    An extractor class to create and pattern match with syntax Annotation(tpe, scalaArgs, javaArgs). Here, tpe is the annotation type, scalaArgs the payload of Scala annotations, and javaArgs the payload of Java annotations.

  4. abstract type ArrayArgument >: Null <: Universe.ArrayArgumentApi with Universe.JavaArgument

    An array argument to a Java annotation as in @Target(value={TYPE,FIELD,METHOD,PARAMETER})

    An array argument to a Java annotation as in @Target(value={TYPE,FIELD,METHOD,PARAMETER})

    Annotations
    @deprecated
    Deprecated

    (Since version 2.11.0) use Annotation.tree to inspect annotation arguments

  5. trait ArrayArgumentApi extends AnyRef

    API of ArrayArgument instances.

    API of ArrayArgument instances. The main source of information about annotations is the scala.reflect.api.Annotations page.

    Annotations
    @deprecated
    Deprecated

    (Since version 2.11.0) use Annotation.tree to inspect annotation arguments

  6. abstract class ArrayArgumentExtractor extends AnyRef

    An extractor class to create and pattern match with syntax ArrayArgument(args) where args is the argument array.

    An extractor class to create and pattern match with syntax ArrayArgument(args) where args is the argument array.

    Annotations
    @deprecated
    Deprecated

    (Since version 2.11.0) use Annotation.tree to inspect annotation arguments

  7. abstract type JavaArgument >: Null <: Universe.JavaArgumentApi

    A Java annotation argument

    A Java annotation argument

    Annotations
    @deprecated
    Deprecated

    (Since version 2.11.0) use Annotation.tree to inspect annotation arguments

  8. trait JavaArgumentApi extends AnyRef

    Has no special methods.

    Has no special methods. Is here to provides erased identity for CompoundType.

    Annotations
    @deprecated
    Deprecated

    (Since version 2.11.0) use Annotation.tree to inspect annotation arguments

  9. abstract type LiteralArgument >: Null <: Universe.LiteralArgumentApi with Universe.JavaArgument

    A literal argument to a Java annotation as "use X instead" in @Deprecated("use X instead")

    A literal argument to a Java annotation as "use X instead" in @Deprecated("use X instead")

    Annotations
    @deprecated
    Deprecated

    (Since version 2.11.0) use Annotation.tree to inspect annotation arguments

  10. trait LiteralArgumentApi extends AnyRef

    The API of LiteralArgument instances.

    The API of LiteralArgument instances. The main source of information about annotations is the scala.reflect.api.Annotations page.

    Annotations
    @deprecated
    Deprecated

    (Since version 2.11.0) use Annotation.tree to inspect annotation arguments

  11. abstract class LiteralArgumentExtractor extends AnyRef

    An extractor class to create and pattern match with syntax LiteralArgument(value) where value is the constant argument.

    An extractor class to create and pattern match with syntax LiteralArgument(value) where value is the constant argument.

    Annotations
    @deprecated
    Deprecated

    (Since version 2.11.0) use Annotation.tree to inspect annotation arguments

  12. abstract type NestedArgument >: Null <: Universe.NestedArgumentApi with Universe.JavaArgument

    A nested annotation argument to a Java annotation as @Nested in @Outer(@Nested).

    A nested annotation argument to a Java annotation as @Nested in @Outer(@Nested).

    Annotations
    @deprecated
    Deprecated

    (Since version 2.11.0) use Annotation.tree to inspect annotation arguments

  13. trait NestedArgumentApi extends AnyRef

    API of NestedArgument instances.

    API of NestedArgument instances. The main source of information about annotations is the scala.reflect.api.Annotations page.

    Annotations
    @deprecated
    Deprecated

    (Since version 2.11.0) use Annotation.tree to inspect annotation arguments

  14. abstract class NestedArgumentExtractor extends AnyRef

    An extractor class to create and pattern match with syntax NestedArgument(annotation) where annotation is the nested annotation.

    An extractor class to create and pattern match with syntax NestedArgument(annotation) where annotation is the nested annotation.

    Annotations
    @deprecated
    Deprecated

    (Since version 2.11.0) use Annotation.tree to inspect annotation arguments

Abstract Value Members

  1. abstract val Annotation: Universe.AnnotationExtractor

    The constructor/extractor for Annotation instances.

  2. abstract def annotationToTree(ann: Universe.Annotation): Universe.Tree
    Attributes
    protected[scala]
  3. abstract def treeToAnnotation(tree: Universe.Tree): Universe.Annotation
    Attributes
    protected[scala]
  4. abstract val ArrayArgument: Universe.ArrayArgumentExtractor

    The constructor/extractor for ArrayArgument instances.

    The constructor/extractor for ArrayArgument instances.

    Annotations
    @deprecated
    Deprecated

    (Since version 2.11.0) use Annotation.tree to inspect annotation arguments

  5. abstract val LiteralArgument: Universe.LiteralArgumentExtractor

    The constructor/extractor for LiteralArgument instances.

    The constructor/extractor for LiteralArgument instances.

    Annotations
    @deprecated
    Deprecated

    (Since version 2.11.0) use Annotation.tree to inspect annotation arguments

  6. abstract val NestedArgument: Universe.NestedArgumentExtractor

    The constructor/extractor for NestedArgument instances.

    The constructor/extractor for NestedArgument instances.

    Annotations
    @deprecated
    Deprecated

    (Since version 2.11.0) use Annotation.tree to inspect annotation arguments

Concrete Value Members

  1. final def !=(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  2. final def ##(): Int
    Definition Classes
    AnyRef → Any
  3. def +(other: String): String
    Implicit
    This member is added by an implicit conversion from Annotations to any2stringadd[Annotations] performed by method any2stringadd in scala.Predef.
    Definition Classes
    any2stringadd
  4. def ->[B](y: B): (Annotations, B)
    Implicit
    This member is added by an implicit conversion from Annotations to ArrowAssoc[Annotations] performed by method ArrowAssoc in scala.Predef.
    Definition Classes
    ArrowAssoc
    Annotations
    @inline()
  5. final def ==(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  6. final def asInstanceOf[T0]: T0
    Definition Classes
    Any
  7. def clone(): AnyRef
    Attributes
    protected[java.lang]
    Definition Classes
    AnyRef
    Annotations
    @native() @throws( ... )
  8. def ensuring(cond: (Annotations) ⇒ Boolean, msg: ⇒ Any): Annotations
    Implicit
    This member is added by an implicit conversion from Annotations to Ensuring[Annotations] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  9. def ensuring(cond: (Annotations) ⇒ Boolean): Annotations
    Implicit
    This member is added by an implicit conversion from Annotations to Ensuring[Annotations] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  10. def ensuring(cond: Boolean, msg: ⇒ Any): Annotations
    Implicit
    This member is added by an implicit conversion from Annotations to Ensuring[Annotations] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  11. def ensuring(cond: Boolean): Annotations
    Implicit
    This member is added by an implicit conversion from Annotations to Ensuring[Annotations] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  12. final def eq(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  13. def equals(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  14. def finalize(): Unit
    Attributes
    protected[java.lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( classOf[java.lang.Throwable] )
  15. def formatted(fmtstr: String): String
    Implicit
    This member is added by an implicit conversion from Annotations to StringFormat[Annotations] performed by method StringFormat in scala.Predef.
    Definition Classes
    StringFormat
    Annotations
    @inline()
  16. final def getClass(): Class[_]
    Definition Classes
    AnyRef → Any
    Annotations
    @native()
  17. def hashCode(): Int
    Definition Classes
    AnyRef → Any
    Annotations
    @native()
  18. final def isInstanceOf[T0]: Boolean
    Definition Classes
    Any
  19. final def ne(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  20. final def notify(): Unit
    Definition Classes
    AnyRef
    Annotations
    @native()
  21. final def notifyAll(): Unit
    Definition Classes
    AnyRef
    Annotations
    @native()
  22. final def synchronized[T0](arg0: ⇒ T0): T0
    Definition Classes
    AnyRef
  23. def toString(): String
    Definition Classes
    AnyRef → Any
  24. final def wait(): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  25. final def wait(arg0: Long, arg1: Int): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  26. final def wait(arg0: Long): Unit
    Definition Classes
    AnyRef
    Annotations
    @native() @throws( ... )
  27. def →[B](y: B): (Annotations, B)
    Implicit
    This member is added by an implicit conversion from Annotations to ArrowAssoc[Annotations] performed by method ArrowAssoc in scala.Predef.
    Definition Classes
    ArrowAssoc

Inherited from AnyRef

Inherited from Any

Inherited by implicit conversion any2stringadd from Annotations to any2stringadd[Annotations]

Inherited by implicit conversion StringFormat from Annotations to StringFormat[Annotations]

Inherited by implicit conversion Ensuring from Annotations to Ensuring[Annotations]

Inherited by implicit conversion ArrowAssoc from Annotations to ArrowAssoc[Annotations]

Annotations

API

The methods available for each reflection entity, without the implementation. Since the reflection entities are later overridden by runtime reflection and macros, their API counterparts guarantee a minimum set of methods that are implemented.

Extractors

Extractors provide the machinery necessary to allow pattern matching and construction of reflection entities that is similar to case classes, although the entities are only abstract types that are later overridden.

Ungrouped