scala.reflect.api

Symbols

trait Symbols extends AnyRef

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(newTermName("test")).asMethod
test: reflect.runtime.universe.MethodSymbol = method test

scala> test.typeSignature
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

Self Type
Universe
Source
Symbols.scala
Linear Supertypes
AnyRef, Any
Known Subclasses
JavaUniverse, Universe, Universe
Type Hierarchy Learn more about scaladoc diagrams
Content Hierarchy Learn more about scaladoc diagrams
Universe.TypeSymbolUniverse.ClassSymbolUniverse.FreeTypeSymbolUniverse.TermSymbolUniverse.MethodSymbolUniverse.ModuleSymbolUniverse.FreeTermSymbolUniverse.Symbol
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Inherited
  1. Symbols
  2. AnyRef
  3. Any
Implicitly
  1. by StringAdd
  2. by StringFormat
  3. by Ensuring
  4. by ArrowAssoc
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  1. Public
  2. All

Type Members

  1. abstract type ClassSymbol >: Null <: Universe.TypeSymbol with Universe.ClassSymbolApi

    The type of class symbols representing class and trait definitions.

  2. trait ClassSymbolApi extends Universe.TypeSymbolApi

    The API of class symbols.

  3. abstract type FreeTermSymbol >: Null <: Universe.TermSymbol with Universe.FreeTermSymbolApi

    The type of free terms introduced by reification.

  4. trait FreeTermSymbolApi extends Universe.TermSymbolApi

    The API of free term symbols.

  5. abstract type FreeTypeSymbol >: Null <: Universe.TypeSymbol with Universe.FreeTypeSymbolApi

    The type of free types introduced by reification.

  6. trait FreeTypeSymbolApi extends Universe.TypeSymbolApi

    The API of free type symbols.

  7. abstract type MethodSymbol >: Null <: Universe.TermSymbol with Universe.MethodSymbolApi

    The type of method symbols representing def declarations.

  8. trait MethodSymbolApi extends Universe.TermSymbolApi

    The API of method symbols.

  9. abstract type ModuleSymbol >: Null <: Universe.TermSymbol with Universe.ModuleSymbolApi

    The type of module symbols representing object declarations.

  10. trait ModuleSymbolApi extends Universe.TermSymbolApi

    The API of module symbols.

  11. abstract type Symbol >: Null <: Universe.SymbolApi

    The type of symbols representing declarations.

  12. trait SymbolApi extends AnyRef

    The API of symbols.

  13. abstract type TermSymbol >: Null <: Universe.Symbol with Universe.TermSymbolApi

    The type of term symbols representing val, var, def, and object declarations as well as packages and value parameters.

  14. trait TermSymbolApi extends Universe.SymbolApi

    The API of term symbols.

  15. abstract type TypeSymbol >: Null <: Universe.Symbol with Universe.TypeSymbolApi

    The type of type symbols representing type, class, and trait declarations, as well as type parameters.

  16. trait TypeSymbolApi extends Universe.SymbolApi

    The API of type symbols.

Abstract Value Members

  1. abstract val NoSymbol: Universe.Symbol

    A special "missing" symbol.

    A special "missing" symbol. Commonly used in the API to denote a default or empty value.

Concrete Value Members

  1. final def !=(arg0: AnyRef): Boolean

    Definition Classes
    AnyRef

  2. final def !=(arg0: Any): Boolean

    Definition Classes
    Any

  3. final def ##(): Int

    Definition Classes
    AnyRef → Any

  4. def +(other: String): String

    Implicit information
    This member is added by an implicit conversion from Symbols to StringAdd[Symbols] performed by method StringAdd in scala.Predef.
    Definition Classes
    StringAdd

  5. def ->[B](y: B): (Symbols, B)

    Implicit information
    This member is added by an implicit conversion from Symbols to ArrowAssoc[Symbols] performed by method ArrowAssoc in scala.Predef.
    Definition Classes
    ArrowAssoc
    Annotations
    @inline()

  6. final def ==(arg0: AnyRef): Boolean

    Definition Classes
    AnyRef

  7. final def ==(arg0: Any): Boolean

    Definition Classes
    Any

  8. final def asInstanceOf[T0]: T0

    Definition Classes
    Any

  9. def clone(): AnyRef

    Attributes
    protected[java.lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )

  10. def ensuring(cond: (Symbols) ⇒ Boolean, msg: ⇒ Any): Symbols

    Implicit information
    This member is added by an implicit conversion from Symbols to Ensuring[Symbols] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring

  11. def ensuring(cond: (Symbols) ⇒ Boolean): Symbols

    Implicit information
    This member is added by an implicit conversion from Symbols to Ensuring[Symbols] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring

  12. def ensuring(cond: Boolean, msg: ⇒ Any): Symbols

    Implicit information
    This member is added by an implicit conversion from Symbols to Ensuring[Symbols] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring

  13. def ensuring(cond: Boolean): Symbols

    Implicit information
    This member is added by an implicit conversion from Symbols to Ensuring[Symbols] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring

  14. final def eq(arg0: AnyRef): Boolean

    Definition Classes
    AnyRef

  15. def equals(arg0: Any): Boolean

    Definition Classes
    AnyRef → Any

  16. def finalize(): Unit

    Attributes
    protected[java.lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( classOf[java.lang.Throwable] )

  17. def formatted(fmtstr: String): String

    Returns string formatted according to given format string.

    Returns string formatted according to given format string. Format strings are as for String.format (@see java.lang.String.format).

    Implicit information
    This member is added by an implicit conversion from Symbols to StringFormat[Symbols] performed by method StringFormat in scala.Predef.
    Definition Classes
    StringFormat
    Annotations
    @inline()

  18. final def getClass(): Class[_]

    Definition Classes
    AnyRef → Any

  19. def hashCode(): Int

    Definition Classes
    AnyRef → Any

  20. final def isInstanceOf[T0]: Boolean

    Definition Classes
    Any

  21. final def ne(arg0: AnyRef): Boolean

    Definition Classes
    AnyRef

  22. final def notify(): Unit

    Definition Classes
    AnyRef

  23. final def notifyAll(): Unit

    Definition Classes
    AnyRef

  24. final def synchronized[T0](arg0: ⇒ T0): T0

    Definition Classes
    AnyRef

  25. def toString(): String

    Definition Classes
    AnyRef → Any

  26. final def wait(): Unit

    Definition Classes
    AnyRef
    Annotations
    @throws( ... )

  27. final def wait(arg0: Long, arg1: Int): Unit

    Definition Classes
    AnyRef
    Annotations
    @throws( ... )

  28. final def wait(arg0: Long): Unit

    Definition Classes
    AnyRef
    Annotations
    @throws( ... )

  29. def →[B](y: B): (Symbols, B)

    Implicit information
    This member is added by an implicit conversion from Symbols to ArrowAssoc[Symbols] performed by method ArrowAssoc in scala.Predef.
    Definition Classes
    ArrowAssoc

Inherited from AnyRef

Inherited from Any

Inherited by implicit conversion StringAdd from Symbols to StringAdd[Symbols]

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

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

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

Symbols

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.

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