Scala Reflection Library2.13.15 < Back
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# Packages

-  package root
  Definition Classes
    root
-  package scala
  Definition Classes
    root
-  package reflect
  Definition Classes
    scala
-  package api

  EXPERIMENTAL

  EXPERIMENTAL

  The Scala Reflection API (located in scala-reflect.jar).

  In Scala 2.10.0, the Scala Reflection API and its implementation have an "experimental" status. This means that the API and the docs are not complete and can be changed in binary- and source-incompatible manner in 2.10.1. This also means that the implementation has some known issues.

  The following types are the backbone of the Scala Reflection API, and serve as a good starting point for information about Scala Reflection:

  - scala.reflect.api.Symbols
  - scala.reflect.api.Types
  - scala.reflect.api.Mirrors
  - scala.reflect.api.Universe

  For more information about Scala Reflection, see the Reflection Guide

  Definition Classes
    reflect
-  trait Symbols extends AnyRef

  EXPERIMENTAL

  EXPERIMENTAL

  This trait defines symbols and operations on them.

  Symbols are used to establish bindings between a name and the entity it refers to, such as a class or a method. Anything you define and can give a name to in Scala has an associated symbol.

  Symbols contain all available information about the declaration of an entity (class/object/trait etc.) or a member (vals/vars/defs etc.), and as such are an integral abstraction central to both runtime reflection and macros.

  A symbol can provide a wealth of information ranging from the basic `name` method available on all symbols to other, more involved, concepts such as getting the `baseClasses` from `ClassSymbol`. Other common use cases of symbols include inspecting members' signatures, getting type parameters of a class, getting the parameter type of a method or finding out the type of a field.

  Example usage of runtime reflection; getting a method's type signature:

      scala> import scala.reflect.runtime.universe._
      import scala.reflect.runtime.universe._

      scala> class C[T] { def test[U](x: T)(y: U): Int = ??? }
      defined class C

      scala> val test = typeOf[C[Int]].member(TermName("test")).asMethod
      test: reflect.runtime.universe.MethodSymbol = method test

      scala> test.info
      res0: reflect.runtime.universe.Type = [U](x: T)(y: U)scala.Int

  Symbols are organized in a hierarchy. For example, a symbol that represents a parameter of a method is owned by the corresponding method symbol, a method symbol is owned by its enclosing class, a class is owned by a containing package and so on.

  Certain types of tree nodes, such as Ident (references to identifiers) and Select (references to members) expose method `symbol` to obtain the symbol that represents their declaration. During the typechecking phase, the compiler looks up the symbol based on the name and scope and sets the `symbol` field of tree nodes.

  For more information about `Symbol` usage and attached intricacies, see the Reflection Guide: Symbols

  Definition Classes
    api
- ClassSymbol
- ClassSymbolApi
- MethodSymbol
- MethodSymbolApi
- ModuleSymbol
- ModuleSymbolApi
- Symbol
- SymbolApi
- TermSymbol
- TermSymbolApi
- TypeSymbol
- TypeSymbolApi

t

scala.reflect.api.Symbols

# SymbolApi

###

#### trait SymbolApi extends AnyRef

The API of symbols. The main source of information about symbols is the Symbols page.

Class Symbol defines `isXXX` test methods such as `isPublic` or `isFinal`, `params` and `returnType` methods for method symbols, `baseClasses` for class symbols and so on. Some of these methods don't make sense for certain subclasses of `Symbol` and return `NoSymbol`, `Nil` or other empty values.

Self Type
  Universe.Symbol
Source
  Symbols.scala

Linear Supertypes
AnyRef, Any
Known Subclasses
FreeTermSymbol, FreeTermSymbolApi, FreeTypeSymbol, FreeTypeSymbolApi, ClassSymbol, ClassSymbolApi, MethodSymbol, MethodSymbolApi, ModuleSymbol, ModuleSymbolApi, Symbol, TermSymbol, TermSymbolApi, TypeSymbol, TypeSymbolApi
Type Hierarchy

Ordering

1. Grouped
2. Alphabetic
3. By Inheritance

Inherited

1. SymbolApi
2. AnyRef
3. Any

Implicitly

1. by any2stringadd
2. by StringFormat
3. by Ensuring
4. by ArrowAssoc

1. Hide All
2. Show All

Visibility

1. Public
2. Protected

### Type Members

1.  abstract type NameType >: Null <: Universe.Name

   The type of the symbol name.

   The type of the symbol name. Can be either `TermName` or `TypeName` depending on whether this is a `TermSymbol` or a `TypeSymbol`.

   Type name namespaces do not intersect with term name namespaces. This fact is reflected in different types for names of `TermSymbol` and `TypeSymbol`.

### Abstract Value Members

1.  abstract def alternatives: List[Universe.Symbol]

   The overloaded alternatives of this symbol.

2.  abstract def annotations: List[Universe.Annotation]

   A list of annotations attached to this Symbol.

3.  abstract def companion: Universe.Symbol

   For a class: its companion object if exists.

   For a class: its companion object if exists. For a module or a module class: companion class of the module if exists. For a package or a package class: NoSymbol. For all others: NoSymbol.

4.  abstract def filter(cond: (Universe.Symbol) => Boolean): Universe.Symbol

   Filters the underlying alternatives (or a single-element list composed of the symbol itself if the symbol is not overloaded).

   Filters the underlying alternatives (or a single-element list composed of the symbol itself if the symbol is not overloaded). Returns an overloaded symbol is there are multiple matches. Returns a NoSymbol if there are no matches.

5.  abstract def fullName: String

   The encoded full path name of this symbol, where outer names and inner names are separated by periods.

6.  abstract def info: Universe.Type

   The type signature of this symbol.

   The type signature of this symbol.

   This method always returns signatures in the most generic way possible, even if the underlying symbol is obtained from an instantiation of a generic type. For example, signature of the method `def map[B](f: (A) => B): List[B]`, which refers to the type parameter `A` of the declaring class `List[A]`, will always feature `A`, regardless of whether `map` is loaded from the `List[_]` or from `List[Int]`. To get a signature with type parameters appropriately instantiated, one should use `infoIn`.

7.  abstract def infoIn(site: Universe.Type): Universe.Type

   The type signature of this symbol seen as a member of given type `site`.

8.  abstract def isAbstract: Boolean

   Is this symbol abstract (i.e.

   Is this symbol abstract (i.e. an abstract class, an abstract method, value or type member)?

9.  abstract def isAbstractOverride: Boolean

   Is this symbol labelled as "abstract override"?

10.  abstract def isConstructor: Boolean

    Does this method represent a constructor?

    Does this method represent a constructor?

    If `owner` is a class, then this is a vanilla JVM constructor. If `owner` is a trait, then this is a mixin constructor.

11.  abstract def isFinal: Boolean

    Is this symbol final?

12.  abstract def isImplementationArtifact: Boolean

    Does this symbol represent an implementation artifact that isn't meant for public use? Examples of such artifacts are erasure bridges and outer fields.

13.  abstract def isImplicit: Boolean

    Does this symbol represent an implicit value, definition, class or parameter?

14.  abstract def isJava: Boolean

    Is this symbol defined by Java?

15.  abstract def isJavaAnnotation: Boolean

    Does this symbol represent a java annotation interface?

16.  abstract def isJavaEnum: Boolean

    Does this symbol represent a java enum class or a java enum value?

17.  abstract def isMacro: Boolean

    Is this symbol a macro?

18.  abstract def isPackage: Boolean

    Does this symbol represent the definition of a package? Known issues: https://github.com/scala/bug/issues/6732.

19.  abstract def isPackageClass: Boolean

    Does this symbol represent a package class? If yes, `isClass` is also guaranteed to be true.

20.  abstract def isParameter: Boolean

    Is this symbol a parameter (either a method parameter or a type parameter)?

21.  abstract def isPrivate: Boolean

    Does this symbol represent a private declaration or definition? If yes, `privateWithin` might tell more about this symbol's visibility scope.

22.  abstract def isPrivateThis: Boolean

    Does this symbol represent a declaration or definition written in a source file as `private[this]` or generated in tree/symbol form with the combination of flags LOCAL and PRIVATE? If yes, `isPrivate` is guaranteed to be true.

23.  abstract def isProtected: Boolean

    Does this symbol represent a protected declaration or definition? If yes, `privateWithin` might tell more about this symbol's visibility scope.

24.  abstract def isProtectedThis: Boolean

    Does this symbol represent a declaration or definition written in a source file as `protected[this]` or generated in tree/symbol form with the combination of flags LOCAL and PROTECTED? If yes, `isProtected` is guaranteed to be true,

25.  abstract def isPublic: Boolean

    Does this symbol represent a public declaration or definition?

26.  abstract def isSpecialized: Boolean

    Is this symbol a specialized type parameter or a generated specialized member?

27.  abstract def isStatic: Boolean

    Is this symbol static (i.e.

    Is this symbol static (i.e. with no outer instance)? Q: When exactly is a sym marked as STATIC? A: If it's a member of a toplevel object, or of an object contained in a toplevel object, or any number of levels deep. https://groups.google.com/group/scala-internals/browse_thread/thread/d385bcd60b08faf6

28.  abstract def isSynthetic: Boolean

    Does this symbol represent a synthetic (i.e.

    Does this symbol represent a synthetic (i.e. a compiler-generated) entity? Examples of synthetic entities are accessors for vals and vars.

29.  abstract def map(f: (Universe.Symbol) => Universe.Symbol): Universe.Symbol

    If this is a NoSymbol, returns NoSymbol, otherwise returns the result of applying `f` to this symbol.

30.  abstract def name: Symbol.NameType

    The name of the symbol as a member of the `Name` type.

31.  abstract def orElse(alt: => Universe.Symbol): Universe.Symbol

    Provides an alternate if symbol is a NoSymbol.

32.  abstract def overrides: List[Universe.Symbol]

    Returns all symbols overridden by this symbol.

33.  abstract def owner: Universe.Symbol

    The owner of this symbol.

    The owner of this symbol. This is the symbol that directly contains the current symbol's definition. The `NoSymbol` symbol does not have an owner, and calling this method on one causes an internal error. The owner of the Scala root class scala.reflect.api.Mirror.RootClass and the Scala root object scala.reflect.api.Mirror.RootPackage is `NoSymbol`. Every other symbol has a chain of owners that ends in scala.reflect.api.Mirror.RootClass.

34.  abstract def pos: Universe.Position

    Position of the tree.

35.  abstract def privateWithin: Universe.Symbol

    Set when symbol has a modifier of the form private[X] or protected[X], NoSymbol otherwise.

    Set when symbol has a modifier of the form private[X] or protected[X], NoSymbol otherwise.

    Access level encoding: there are three scala flags (PRIVATE, PROTECTED, and LOCAL) which combine with value privateWithin (the "foo" in private[foo]) to define from where an entity can be accessed. The meanings are as follows:

    PRIVATE access restricted to class only. PROTECTED access restricted to class and subclasses only. LOCAL can only be set in conjunction with PRIVATE or PROTECTED. Further restricts access to the same object instance.

    In addition, privateWithin can be used to set a visibility barrier. When set, everything contained in the named enclosing package or class has access. It is incompatible with PRIVATE or LOCAL, but is additive with PROTECTED (i.e. if either the flags or privateWithin allow access, then it is allowed.)

    The java access levels translate as follows:

    java private: isPrivate && (privateWithin == NoSymbol) java package: !isPrivate && !isProtected && (privateWithin == enclosingPackage) java protected: isProtected && (privateWithin == enclosingPackage) java public: !isPrivate && !isProtected && (privateWithin == NoSymbol)

36.  abstract def suchThat(cond: (Universe.Symbol) => Boolean): Universe.Symbol

    Does the same as `filter`, but crashes if there are multiple matches.

37.  abstract def typeSignature: Universe.Type

    See also

      info

38.  abstract def typeSignatureIn(site: Universe.Type): Universe.Type

    See also

      infoIn

39.  abstract def allOverriddenSymbols: List[Universe.Symbol]

    Annotations
      @deprecated
    Deprecated

      (Since version 2.11.0) use `overrides` instead

    See also

      overrides

40.  abstract def associatedFile: AbstractFile

    Source file if this symbol is created during this compilation run, or a class file if this symbol is loaded from a *.class or *.jar.

    Source file if this symbol is created during this compilation run, or a class file if this symbol is loaded from a *.class or *.jar.

    The return type is `scala.reflect.io.AbstractFile`, which belongs to an experimental part of Scala reflection. It should not be used unless you know what you are doing. In subsequent releases, this API will be refined and exposed as a part of scala.reflect.api.

    Annotations
      @deprecated
    Deprecated

      (Since version 2.11.0) use `pos.source.file` instead

41.  abstract def companionSymbol: Universe.Symbol

    For a class: the module or case class factory with the same name in the same package.

    For a class: the module or case class factory with the same name in the same package. For a module: the class with the same name in the same package. For all others: NoSymbol.

    This API may return unexpected results for module classes, packages and package classes. Use `companion` instead in order to get predictable results.

    Annotations
      @deprecated
    Deprecated

      (Since version 2.11.0) use `companion` instead, but beware of possible changes in behavior

### 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 Universe.SymbolApi toany2stringadd[Universe.SymbolApi] performed by method any2stringadd in scala.Predef.
   Definition Classes
     any2stringadd
4.  def ->[B](y: B): (Universe.SymbolApi, B)
   Implicit
     This member is added by an implicit conversion from Universe.SymbolApi toArrowAssoc[Universe.SymbolApi] performed by method ArrowAssoc in scala.Predef.
   Definition Classes
     ArrowAssoc
   Annotations
     @inline()
5.  final def ==(arg0: Any): Boolean
   Definition Classes
     AnyRef → Any
6.  def asClass: Universe.ClassSymbol

   This symbol cast to a ClassSymbol representing a class or trait.

   This symbol cast to a ClassSymbol representing a class or trait.

   Exceptions thrown

     `ScalaReflectionException` if `isClass` is false.

7.  final def asInstanceOf[T0]: T0
   Definition Classes
     Any
8.  def asMethod: Universe.MethodSymbol

   This symbol cast to a MethodSymbol.

   This symbol cast to a MethodSymbol.

   Exceptions thrown

     `ScalaReflectionException` if `isMethod` is false.

9.  def asModule: Universe.ModuleSymbol

   This symbol cast to a ModuleSymbol defined by an object definition.

   This symbol cast to a ModuleSymbol defined by an object definition.

   Exceptions thrown

     `ScalaReflectionException` if `isModule` is false.

10.  def asTerm: Universe.TermSymbol

    This symbol cast to a TermSymbol.

    This symbol cast to a TermSymbol.

    Exceptions thrown

      `ScalaReflectionException` if `isTerm` is false.

11.  def asType: Universe.TypeSymbol

    This symbol cast to a TypeSymbol.

    This symbol cast to a TypeSymbol.

    Exceptions thrown

      `ScalaReflectionException` if `isType` is false.

12.  def clone(): AnyRef
    Attributes
      protected[lang]
    Definition Classes
      AnyRef
    Annotations
      @throws(classOf[java.lang.CloneNotSupportedException]) @native()
13.  def ensuring(cond: (Universe.SymbolApi) => Boolean, msg: => Any): Universe.SymbolApi
    Implicit
      This member is added by an implicit conversion from Universe.SymbolApi toEnsuring[Universe.SymbolApi] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring
14.  def ensuring(cond: (Universe.SymbolApi) => Boolean): Universe.SymbolApi
    Implicit
      This member is added by an implicit conversion from Universe.SymbolApi toEnsuring[Universe.SymbolApi] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring
15.  def ensuring(cond: Boolean, msg: => Any): Universe.SymbolApi
    Implicit
      This member is added by an implicit conversion from Universe.SymbolApi toEnsuring[Universe.SymbolApi] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring
16.  def ensuring(cond: Boolean): Universe.SymbolApi
    Implicit
      This member is added by an implicit conversion from Universe.SymbolApi toEnsuring[Universe.SymbolApi] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring
17.  final def eq(arg0: AnyRef): Boolean
    Definition Classes
      AnyRef
18.  def equals(arg0: AnyRef): Boolean
    Definition Classes
      AnyRef → Any
19.  def finalize(): Unit
    Attributes
      protected[lang]
    Definition Classes
      AnyRef
    Annotations
      @throws(classOf[java.lang.Throwable])
20.  final def getClass(): Class[_ <: AnyRef]
    Definition Classes
      AnyRef → Any
    Annotations
      @native()
21.  def hashCode(): Int
    Definition Classes
      AnyRef → Any
    Annotations
      @native()
22.  def isClass: Boolean

    Does this symbol represent the definition of a class or trait? If yes, `isType` is also guaranteed to be true.

23.  final def isInstanceOf[T0]: Boolean
    Definition Classes
      Any
24.  def isMethod: Boolean

    Does this symbol represent the definition of a method? If yes, `isTerm` is also guaranteed to be true.

25.  def isModule: Boolean

    Does this symbol represent the definition of a module (i.e.

    Does this symbol represent the definition of a module (i.e. it results from an object definition?). If yes, `isTerm` is also guaranteed to be true.

26.  def isModuleClass: Boolean

    Does this symbol represent the definition of a class implicitly associated with an object definition (module class in scala compiler parlance)? If yes, `isType` is also guaranteed to be true.

27.  def isOverloadedMethod: Boolean

    Used to provide a better error message for `asMethod`.

    Used to provide a better error message for `asMethod`.

    Attributes
      protected
28.  def isTerm: Boolean

    Does this symbol represent the definition of a term? Note that every symbol is either a term or a type.

    Does this symbol represent the definition of a term? Note that every symbol is either a term or a type. So for every symbol `sym` (except for `NoSymbol`), either `sym.isTerm` is true or `sym.isType` is true.

29.  def isType: Boolean

    Does this symbol represent the definition of a type? Note that every symbol is either a term or a type.

    Does this symbol represent the definition of a type? Note that every symbol is either a term or a type. So for every symbol `sym` (except for `NoSymbol`), either `sym.isTerm` is true or `sym.isType` is true.

30.  final def ne(arg0: AnyRef): Boolean
    Definition Classes
      AnyRef
31.  final def notify(): Unit
    Definition Classes
      AnyRef
    Annotations
      @native()
32.  final def notifyAll(): Unit
    Definition Classes
      AnyRef
    Annotations
      @native()
33.  final def synchronized[T0](arg0: => T0): T0
    Definition Classes
      AnyRef
34.  def toString(): String
    Definition Classes
      AnyRef → Any
35.  final def wait(): Unit
    Definition Classes
      AnyRef
    Annotations
      @throws(classOf[java.lang.InterruptedException])
36.  final def wait(arg0: Long, arg1: Int): Unit
    Definition Classes
      AnyRef
    Annotations
      @throws(classOf[java.lang.InterruptedException])
37.  final def wait(arg0: Long): Unit
    Definition Classes
      AnyRef
    Annotations
      @throws(classOf[java.lang.InterruptedException]) @native()

### Deprecated Value Members

1.  def formatted(fmtstr: String): String
   Implicit
     This member is added by an implicit conversion from Universe.SymbolApi toStringFormat[Universe.SymbolApi] performed by method StringFormat in scala.Predef.
   Definition Classes
     StringFormat
   Annotations
     @deprecated @inline()
   Deprecated

     (Since version 2.12.16) Use `formatString.format(value)` instead of `value.formatted(formatString)`, or use the `f""` string interpolator. In Java 15 and later, `formatted` resolves to the new method in String which has reversed parameters.

2.  def →[B](y: B): (Universe.SymbolApi, B)
   Implicit
     This member is added by an implicit conversion from Universe.SymbolApi toArrowAssoc[Universe.SymbolApi] performed by method ArrowAssoc in scala.Predef.
   Definition Classes
     ArrowAssoc
   Annotations
     @deprecated
   Deprecated

     (Since version 2.13.0) Use `->` instead. If you still wish to display it as one character, consider using a font with programming ligatures such as Fira Code.

### Inherited from AnyRef

### Inherited from Any

### Inherited by implicit conversion any2stringadd fromUniverse.SymbolApi to any2stringadd[Universe.SymbolApi]

### Inherited by implicit conversion StringFormat fromUniverse.SymbolApi to StringFormat[Universe.SymbolApi]

### Inherited by implicit conversion Ensuring fromUniverse.SymbolApi to Ensuring[Universe.SymbolApi]

### Inherited by implicit conversion ArrowAssoc fromUniverse.SymbolApi to ArrowAssoc[Universe.SymbolApi]

### Method Symbol Members

### Symbol Basic Information

### Symbol Type Tests

### Symbol Conversions

### Iteration Helpers

These methods enable collections-like operations on symbols.

### Ungrouped