Trait 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(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

Self Type
Universe
Source
Symbols.scala
Linear Supertypes
Known Subclasses

Type Members

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

trait ClassSymbolApi extends Universe.TypeSymbolApi

The API of class 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.

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

trait MethodSymbolApi extends Universe.TermSymbolApi

The API of method 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.

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

trait ModuleSymbolApi extends Universe.TermSymbolApi

The API of module 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.

abstract type Symbol >: Null <: Universe.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.

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

trait TermSymbolApi extends Universe.SymbolApi

The API of term 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.

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

trait TypeSymbolApi extends Universe.SymbolApi

The API of type 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.

Abstract Value Members

abstract val NoSymbol: Universe.Symbol

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

Concrete Value Members

final def !=(arg0: Any): Boolean

Definition Classes
AnyRef → Any

final def ##(): Int

Definition Classes
AnyRef → Any

def +(other: String): String

Implicit
This member is added by an implicit conversion from Symbols to any2stringadd[Symbols] performed by method any2stringadd in scala.Predef.
Definition Classes
any2stringadd

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

Implicit
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()

final def ==(arg0: Any): Boolean

Definition Classes
AnyRef → Any

final def asInstanceOf[T0]: T0

Definition Classes
Any

def clone(): AnyRef

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

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

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

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

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

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

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

def ensuring(cond: Boolean): Symbols

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

final def eq(arg0: AnyRef): Boolean

Definition Classes
AnyRef

def equals(arg0: Any): Boolean

Definition Classes
AnyRef → Any

def finalize(): Unit

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

def formatted(fmtstr: String): String

Implicit
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()

final def getClass(): Class[_]

Definition Classes
AnyRef → Any
Annotations
@native()

def hashCode(): Int

Definition Classes
AnyRef → Any
Annotations
@native()

final def isInstanceOf[T0]: Boolean

Definition Classes
Any

final def ne(arg0: AnyRef): Boolean

Definition Classes
AnyRef

final def notify(): Unit

Definition Classes
AnyRef
Annotations
@native()

final def notifyAll(): Unit

Definition Classes
AnyRef
Annotations
@native()

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

Definition Classes
AnyRef

def toString(): String

Definition Classes
AnyRef → Any

final def wait(): Unit

Definition Classes
AnyRef
Annotations
@throws( ... )

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

Definition Classes
AnyRef
Annotations
@throws( ... )

final def wait(arg0: Long): Unit

Definition Classes
AnyRef
Annotations
@throws( ... ) @native()

def [B](y: B): (Symbols, B)

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

© 2002-2019 EPFL, with contributions from Lightbend.
Licensed under the Apache License, Version 2.0.
https://www.scala-lang.org/api/2.12.9/scala-reflect/scala/reflect/api/Symbols.html