Scala Reflection Library2.12.2-20170504-135222-21d12e9 < 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
- Annotations
- Constants
- Exprs
- FlagSets
- ImplicitTags
- Internals
- JavaUniverse
- Liftables
- Mirror
- Mirrors
- Names
- Position
- Positions
- Printers
- Quasiquotes
- Scopes
- StandardDefinitions
- StandardLiftables
- StandardNames
- Symbols
- TreeCreator
- Trees
- TypeCreator
- TypeTags
- Types
- Universe

t

scala.reflect.api

# Mirrors 

###

#### trait Mirrors extends AnyRef

EXPERIMENTAL

This trait provides support for Mirrors in the Scala Reflection API.

`Mirror`s are a central part of Scala Reflection. All information provided by reflection is made accessible through `Mirror`s. Depending on the type of information to be obtained, or the reflective action to be taken, different flavors of mirrors must be used. "Classloader" mirrors can be used to obtain representations of types and members. From a classloader `Mirror`, it's possible to obtain more specialized "invoker" `Mirror`s (the most commonly-used mirrors), which implement reflective invocations, such as method/constructor calls and field accesses.

The two flavors of mirrors:

- “Classloader” mirrors. These mirrors translate names to symbols (via methods `staticClass`/`staticModule`/`staticPackage`).
- "Invoker” mirrors. These mirrors implement reflective invocations (via methods `MethodMirror.apply`, `FieldMirror.get`, etc). These "invoker" mirrors are the types of mirrors that are most commonly used.

##### Compile-time Mirrors

Compile-time `Mirror`s make use of only classloader `Mirror`s to load `Symbol`s by name.

The entry point to classloader `Mirror`s is via scala.reflect.macros.blackbox.Context#mirror or scala.reflect.macros.whitebox.Context#mirror. Typical methods which use classloader `Mirror`s include scala.reflect.api.Mirror#staticClass, scala.reflect.api.Mirror#staticModule, and scala.reflect.api.Mirror#staticPackage. For example:

    import scala.reflect.macros.blackbox.Context

    case class Location(filename: String, line: Int, column: Int)

    object Macros {
      def currentLocation: Location = macro impl

      def impl(c: Context): c.Expr[Location] = {
        import c.universe._
        val pos = c.macroApplication.pos
        val clsLocation = c.mirror.staticModule("Location") // get symbol of "Location" object
        c.Expr(Apply(Ident(clsLocation), List(Literal(Constant(pos.source.path)), Literal(Constant(pos.line)), Literal(Constant(pos.column)))))
      }
    }

Of Note: There are several high-level alternatives that one can use to avoid having to manually lookup symbols. For example, `typeOf[Location.type].termSymbol` (or `typeOf[Location].typeSymbol` if we needed a `ClassSymbol`), which are type safe since we don’t have to use `String`s to lookup the `Symbol`.

##### Runtime Mirrors

Runtime `Mirror`s make use of both classloader and invoker `Mirror`s.

The entry point to `Mirror`s for use at runtime is via `ru.runtimeMirror(<classloader>)`, where `ru` is scala.reflect.runtime.universe.

The result of a scala.reflect.api.JavaUniverse#runtimeMirror call is a classloader mirror, of type scala.reflect.api.Mirrors#ReflectiveMirror, which can load symbols by names as discussed above (in the “Compile-time” section).

A classloader mirror can create invoker mirrors, which include: scala.reflect.api.Mirrors#InstanceMirror, scala.reflect.api.Mirrors#MethodMirror, scala.reflect.api.Mirrors#FieldMirror, scala.reflect.api.Mirrors#ClassMirror and scala.reflect.api.Mirrors#ModuleMirror.

Examples of how these two types of `Mirror`s interact are available below.

##### Types of Mirrors, Their Use Cases & Examples

scala.reflect.api.Mirrors#ReflectiveMirror. Used for loading `Symbol`s by name, and as an entry point into invoker mirrors. Entry point: `val m = ru.runtimeMirror(<classloader>)`. Example:

    scala> val ru = scala.reflect.runtime.universe
    ru: scala.reflect.api.JavaUniverse = ...

    scala> val m = ru.runtimeMirror(getClass.getClassLoader)
    m: reflect.runtime.universe.Mirror = JavaMirror ...

scala.reflect.api.Mirrors#InstanceMirror. Used for creating invoker `Mirror`s for methods and fields and for inner classes and inner objects (modules). Entry point: `val im = m.reflect(<value>)`. Example:

    scala> class C { def x = 2 }
    defined class C

    scala> val im = m.reflect(new C)
    im: reflect.runtime.universe.InstanceMirror = instance mirror for C@3442299e

scala.reflect.api.Mirrors#MethodMirror. Used for invoking instance methods (Scala only has instance methods-- methods of objects are instance methods of object instances, obtainable via `ModuleMirror.instance`). Entry point: `val mm = im.reflectMethod(<method symbol>)`. Example:

    scala> val methodX = typeOf[C].declaration(TermName("x")).asMethod
    methodX: reflect.runtime.universe.MethodSymbol = method x

    scala> val mm = im.reflectMethod(methodX)
    mm: reflect.runtime.universe.MethodMirror = method mirror for C.x: scala.Int (bound to C@3442299e)

    scala> mm()
    res0: Any = 2

scala.reflect.api.Mirrors#FieldMirror. Used for getting/setting instance fields (Scala only has instance fields-- fields of objects are instance methods of object instances obtainable via ModuleMirror.instance). Entry point: `val fm = im.reflectMethod(<field or accessor symbol>)`. Example:

    scala> class C { val x = 2; val y = 3 }
    defined class C

    scala> val m = ru.runtimeMirror(getClass.getClassLoader)
    m: reflect.runtime.universe.Mirror = JavaMirror ...

    scala> val im = m.reflect(new C)
    im: reflect.runtime.universe.InstanceMirror = instance mirror for C@5f0c8ac1

    scala> val fieldX = typeOf[C].declaration(TermName("x")).asTerm.accessed.asTerm
    fieldX: reflect.runtime.universe.TermSymbol = value x
    scala> val fmX = im.reflectField(fieldX)
    fmX: reflect.runtime.universe.FieldMirror = field mirror for C.x (bound to C@5f0c8ac1)

    scala> fmX.get
    res0: Any = 2

    scala> fmX.set(3) // NOTE: can set an underlying value of an immutable field!

    scala> val fieldY = typeOf[C].declaration(TermName("y")).asTerm.accessed.asTerm
    fieldY: reflect.runtime.universe.TermSymbol = variable y

    scala> val fmY = im.reflectField(fieldY)
    fmY: reflect.runtime.universe.FieldMirror = field mirror for C.y (bound to C@5f0c8ac1)

    scala> fmY.get
    res1: Any = 3

    scala> fmY.set(4)

    scala> fmY.get
    res2: Any = 4

scala.reflect.api.Mirrors#ClassMirror. Used for creating invoker mirrors for constructors. Entry points: for static classes `val cm1 = m.reflectClass(<class symbol>)`, for inner classes `val mm2 = im.reflectClass(<class symbol>)`. Example:

    scala> case class C(x: Int)
    defined class C

    scala> val m = ru.runtimeMirror(getClass.getClassLoader)
    m: reflect.runtime.universe.Mirror = JavaMirror ...

    scala> val classC = typeOf[C].typeSymbol.asClass

    classC: reflect.runtime.universe.Symbol = class C

    scala> val cm = m.reflectClass(classC)
    cm: reflect.runtime.universe.ClassMirror = class mirror for C (bound to null)

    scala> val ctorC = typeOf[C].declaration(ru.nme.CONSTRUCTOR).asMethod
    ctorC: reflect.runtime.universe.MethodSymbol = constructor C

    scala> val ctorm = cm.reflectConstructor(ctorC)
    ctorm: reflect.runtime.universe.MethodMirror = constructor mirror for C.<init>(x: scala.Int): C (bound to null)

    scala> ctorm(2)
    res0: Any = C(2)

scala.reflect.api.Mirrors#ModuleMirror. Used for getting singleton instances of objects. Entry points: for static objects (modules) `val mm1 = m.reflectModule(<module symbol>)`, for inner objects (modules) `val mm2 = im.reflectModule(<module symbol>)`. Example:

    scala> object C { def x = 2 }
    defined module C

    scala> val m = ru.runtimeMirror(getClass.getClassLoader)
    m: reflect.runtime.universe.Mirror = JavaMirror ...

    scala> val objectC = typeOf[C.type].termSymbol.asModule
    objectC: reflect.runtime.universe.ModuleSymbol = object C

    scala> val mm = m.reflectModule(objectC)
    mm: reflect.runtime.universe.ModuleMirror = module mirror for C (bound to null)

    scala> val obj = mm.instance
    obj: Any = C$@1005ec04

For more information about `Mirrors`s, see the Reflection Guide: Mirrors

Self Type
  Universe
Source
  Mirrors.scala

Linear Supertypes
AnyRef, Any
Known Subclasses
JavaUniverse, Universe, Universe
Type Hierarchy
Content Hierarchy
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Inherited

1. Mirrors
2. AnyRef
3. Any

Implicitly

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

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### Type Members

1.  trait ClassMirror extends Universe.TemplateMirror

   A mirror that reflects the instance parts of a runtime class.

   A mirror that reflects the instance parts of a runtime class. See the overview page for details on how to use runtime reflection.

2.  trait FieldMirror extends AnyRef

   A mirror that reflects a field.

   A mirror that reflects a field. See the overview page for details on how to use runtime reflection.

3.  trait InstanceMirror extends AnyRef

   A mirror that reflects a runtime value.

   A mirror that reflects a runtime value. See the overview page for details on how to use runtime reflection.

4.  trait MethodMirror extends AnyRef

   A mirror that reflects a method.

   A mirror that reflects a method. See the overview page for details on how to use runtime reflection.

5.  abstract type Mirror >: Null <: api.Mirror[Mirrors.this.type]

   The base type of all mirrors of this universe.

   The base type of all mirrors of this universe.

   This abstract type conforms the base interface for all mirrors defined in scala.reflect.api.Mirror and is gradually refined in specific universes (e.g. `Mirror` of a scala.reflect.api.JavaUniverse is capable of reflection).

6.  trait ModuleMirror extends Universe.TemplateMirror

   A mirror that reflects a Scala object definition or the static parts of a runtime class.

   A mirror that reflects a Scala object definition or the static parts of a runtime class. See the overview page for details on how to use runtime reflection.

7.  trait ReflectiveMirror extends api.Mirror[Mirrors.this.type]

   A mirror that reflects instances and static classes.

   A mirror that reflects instances and static classes. See the overview page for details on how to use runtime reflection.

8.  abstract type RuntimeClass >: Null <: AnyRef

   Abstracts the runtime representation of a class on the underlying platform.

9.  trait RuntimeClassApi extends AnyRef

   Has no special methods.

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

10.  trait RuntimeMirror extends api.Mirror[Mirrors.this.type] with Universe.ReflectiveMirror

    The API of a mirror for a reflective universe.

    The API of a mirror for a reflective universe. See the overview page for details on how to use runtime reflection.

11.  trait TemplateMirror extends AnyRef

    A mirror that reflects the instance or static parts of a runtime class.

    A mirror that reflects the instance or static parts of a runtime class. See the overview page for details on how to use runtime reflection.

### Abstract Value Members

1.  abstract val rootMirror: Universe.Mirror

   The root mirror of this universe.

   The root mirror of this universe. This mirror contains standard Scala classes and types such as `Any`, `AnyRef`, `AnyVal`, `Nothing`, `Null`, and all classes loaded from scala-library, which are shared across all mirrors within the enclosing universe.

### 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 Mirrors to any2stringadd[Mirrors] performed by method any2stringadd in scala.Predef.
   Definition Classes
     any2stringadd
4.  def ->[B](y: B): (Mirrors, B)
   Implicit
     This member is added by an implicit conversion from Mirrors to ArrowAssoc[Mirrors] 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
     @throws( ... )
8.  def ensuring(cond: (Mirrors) ⇒ Boolean, msg: ⇒ Any): Mirrors
   Implicit
     This member is added by an implicit conversion from Mirrors to Ensuring[Mirrors] performed by method Ensuring in scala.Predef.
   Definition Classes
     Ensuring
9.  def ensuring(cond: (Mirrors) ⇒ Boolean): Mirrors
   Implicit
     This member is added by an implicit conversion from Mirrors to Ensuring[Mirrors] performed by method Ensuring in scala.Predef.
   Definition Classes
     Ensuring
10.  def ensuring(cond: Boolean, msg: ⇒ Any): Mirrors
    Implicit
      This member is added by an implicit conversion from Mirrors to Ensuring[Mirrors] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring
11.  def ensuring(cond: Boolean): Mirrors
    Implicit
      This member is added by an implicit conversion from Mirrors to Ensuring[Mirrors] 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 Mirrors to StringFormat[Mirrors] performed by method StringFormat in scala.Predef.
    Definition Classes
      StringFormat
    Annotations
      @inline()
16.  final def getClass(): Class[_]
    Definition Classes
      AnyRef → Any
17.  def hashCode(): Int
    Definition Classes
      AnyRef → Any
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
21.  final def notifyAll(): Unit
    Definition Classes
      AnyRef
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
      @throws( ... )
27.  def →[B](y: B): (Mirrors, B)
    Implicit
      This member is added by an implicit conversion from Mirrors to ArrowAssoc[Mirrors] performed by method ArrowAssoc in scala.Predef.
    Definition Classes
      ArrowAssoc

### Inherited from AnyRef

### Inherited from Any

### Inherited by implicit conversion any2stringadd from Mirrors to any2stringadd[Mirrors]

### Inherited by implicit conversion StringFormat from Mirrors to StringFormat[Mirrors]

### Inherited by implicit conversion Ensuring from Mirrors to Ensuring[Mirrors]

### Inherited by implicit conversion ArrowAssoc from Mirrors to ArrowAssoc[Mirrors]

### Mirrors

### 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.

### Ungrouped