scala

# reflect

#### package reflect

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  package.scala

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### Type Members

1. #### abstract class AnyValManifest[T <: AnyVal] extends Manifest[T] with Equals

   Annotations
     @SerialVersionUID()

2. #### trait ClassTag[T] extends ClassManifestDeprecatedApis[T] with Equals with Serializable

   A `ClassTag[T]` stores the erased class of a given type `T`, accessible via the `runtimeClass` field.

   A `ClassTag[T]` stores the erased class of a given type `T`, accessible via the `runtimeClass` field. This is particularly useful for instantiating `Array`s whose element types are unknown at compile time.

   `ClassTag`s are a weaker special case of scala.reflect.api.TypeTags#TypeTags, in that they wrap only the runtime class of a given type, whereas a `TypeTag` contains all static type information. That is, `ClassTag`s are constructed from knowing only the top-level class of a type, without necessarily knowing all of its argument types. This runtime information is enough for runtime `Array` creation.

   For example:

       scala> def mkArray[T : ClassTag](elems: T*) = Array[T](elems: _*)
       mkArray: [T](elems: T*)(implicit evidence$1: scala.reflect.ClassTag[T])Array[T]

       scala> mkArray(42, 13)
       res0: Array[Int] = Array(42, 13)

       scala> mkArray("Japan","Brazil","Germany")
       res1: Array[String] = Array(Japan, Brazil, Germany)

   See scala.reflect.api.TypeTags for more examples, or the Reflection Guide: TypeTags for more details.

   Annotations
     @implicitNotFound( msg = "No ClassTag available for ${T}" )

3. #### trait Manifest[T] extends ClassManifest[T] with Equals

   A `Manifest[T]` is an opaque descriptor for type T.

   A `Manifest[T]` is an opaque descriptor for type T. Its supported use is to give access to the erasure of the type as a `Class` instance, as is necessary for the creation of native `Arrays` if the class is not known at compile time.

   The type-relation operators `<:<` and `=:=` should be considered approximations only, as there are numerous aspects of type conformance which are not yet adequately represented in manifests.

   Example usages:

       def arr[T] = new Array[T](0)                          // does not compile
       def arr[T](implicit m: Manifest[T]) = new Array[T](0) // compiles
       def arr[T: Manifest] = new Array[T](0)                // shorthand for the preceding

       // Methods manifest, classManifest, and optManifest are in [[scala.Predef]].
       def isApproxSubType[T: Manifest, U: Manifest] = manifest[T] <:< manifest[U]
       isApproxSubType[List[String], List[AnyRef]] // true
       isApproxSubType[List[String], List[Int]]    // false

       def methods[T: ClassManifest] = classManifest[T].erasure.getMethods
       def retType[T: ClassManifest](name: String) =
         methods[T] find (_.getName == name) map (_.getGenericReturnType)

       retType[Map[_, _]]("values")  // Some(scala.collection.Iterable)

   Annotations
     @implicitNotFound( msg = "No Manifest available for ${T}." )

4. #### trait OptManifest[+T] extends Serializable

   A `OptManifest[T]` is an optional scala.reflect.Manifest.

   A `OptManifest[T]` is an optional scala.reflect.Manifest.

   It is either a `Manifest` or the value `NoManifest`.

5. #### type ClassManifest[T] = ClassTag[T]

   A `ClassManifest[T]` is an opaque descriptor for type `T`.

   A `ClassManifest[T]` is an opaque descriptor for type `T`. It is used by the compiler to preserve information necessary for instantiating `Arrays` in those cases where the element type is unknown at compile time.

   The type-relation operators make an effort to present a more accurate picture than can be realized with erased types, but they should not be relied upon to give correct answers. In particular they are likely to be wrong when variance is involved or when a subtype has a different number of type arguments than a supertype.

   Annotations
     @deprecated @implicitNotFound( msg = ... )
   Deprecated

     (Since version 2.10.0) Use scala.reflect.ClassTag instead

6. #### trait ClassManifestDeprecatedApis[T] extends OptManifest[T]

   Annotations
     @deprecated
   Deprecated

     (Since version 2.10.0) Use scala.reflect.ClassTag instead

### Value Members

1. #### object ClassManifestFactory

   `ClassManifestFactory` defines factory methods for manifests.

   `ClassManifestFactory` defines factory methods for manifests. It is intended for use by the compiler and should not be used in client code.

   Unlike `ClassManifest`, this factory isn't annotated with a deprecation warning. This is done to prevent avalanches of deprecation warnings in the code that calls methods with manifests.

   In a perfect world, we would just remove the @deprecated annotation from `ClassManifest` the object and then delete it in 2.11. After all, that object is explicitly marked as internal, so noone should use it. However a lot of existing libraries disregarded the scaladoc that comes with `ClassManifest`, so we need to somehow nudge them into migrating prior to removing stuff out of the blue. Hence we've introduced this design decision as the lesser of two evils.

2. #### object ClassTag extends Serializable

   Class tags corresponding to primitive types and constructor/extractor for ClassTags.

3. #### val Manifest: ManifestFactory.type

   The object `Manifest` defines factory methods for manifests.

   The object `Manifest` defines factory methods for manifests. It is intended for use by the compiler and should not be used in client code.

4. #### object ManifestFactory

   `ManifestFactory` defines factory methods for manifests.

   `ManifestFactory` defines factory methods for manifests. It is intended for use by the compiler and should not be used in client code.

   Unlike `Manifest`, this factory isn't annotated with a deprecation warning. This is done to prevent avalanches of deprecation warnings in the code that calls methods with manifests. Why so complicated? Read up the comments for `ClassManifestFactory`.

5. #### object NameTransformer

   Provides functions to encode and decode Scala symbolic names.

   Provides functions to encode and decode Scala symbolic names. Also provides some constants.

6. #### object NoManifest extends OptManifest[Nothing] with Serializable

   One of the branches of an scala.reflect.OptManifest.

7. #### def classTag[T](implicit ctag: ClassTag[T]): ClassTag[T]

8. #### def ensureAccessible[T <: AccessibleObject](m: T): T

   Make a java reflection object accessible, if it is not already and it is possible to do so.

   Make a java reflection object accessible, if it is not already and it is possible to do so. If a SecurityException is thrown in the attempt, it is caught and discarded.

### Deprecated Value Members

1. #### val ClassManifest: ClassManifestFactory.type

   The object `ClassManifest` defines factory methods for manifests.

   The object `ClassManifest` defines factory methods for manifests. It is intended for use by the compiler and should not be used in client code.

   Annotations
     @deprecated
   Deprecated

     (Since version 2.10.0) Use scala.reflect.ClassTag instead

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