Manifest (original) (raw)
scala.reflect.Manifest
See theManifest companion object
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 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: Manifest] = manifest[T].runtimeClass.getMethods
def retType[T: Manifest](name: String) =
methods[T] find (_.getName == name) map (_.getGenericReturnType)
retType[Map[_, _]]("values") // Some(scala.collection.Iterable<B>)
Attributes
Companion
Source
Graph
Supertypes
Known subtypes
Members list
Checks whether this instance can possibly equal that.
Checks whether this instance can possibly equal that.
A method that should be called from every well-designed equals method that is open to be overridden in a subclass. See Programming in Scala, Chapter 28 for discussion and design.
Value parameters
that
the value being probed for possible equality
Attributes
Returns
true if this instance can possibly equal that, otherwise false
Definition Classes
Source
Note: testing for erasure here is important, as it is many times faster than <:< and rules out most comparisons.
Note: testing for erasure here is important, as it is many times faster than <:< and rules out most comparisons.
Attributes
Definition Classes
Source
Calculates a hash code value for the object.
Calculates a hash code value for the object.
The default hashing algorithm is platform dependent.
Note that it is allowed for two objects to have identical hash codes (o1.hashCode.equals(o2.hashCode)) yet not be equal (o1.equals(o2) returns false). A degenerate implementation could always return 0. However, it is required that if two objects are equal (o1.equals(o2) returns true) that they have identical hash codes (o1.hashCode.equals(o2.hashCode)). Therefore, when overriding this method, be sure to verify that the behavior is consistent with the equals method.
Attributes
Returns
the hash code value for this object.
Definition Classes
Source
Produces a new array with element type T and length len
Produces a new array with element type T and length len
Attributes
Inherited from:
Source
Returns a string representation of the object.
Returns a string representation of the object.
The default representation is platform dependent.
Attributes
Returns
a string representation of the object.
Definition Classes
Inherited from:
Source
A ClassTag[T] can serve as an extractor that matches only objects of type T.
A ClassTag[T] can serve as an extractor that matches only objects of type T.
The compiler tries to turn unchecked type tests in pattern matches into checked ones by wrapping a (_: T) type pattern as ct(_: T), where ct is the ClassTag[T] instance. Type tests necessary before calling other extractors are treated similarly. SomeExtractor(...) is turned into ct(SomeExtractor(...)) if T in SomeExtractor.unapply(x: T) is uncheckable, but we have an instance of ClassTag[T].
Attributes
Inherited from:
Source
Produces a ClassTag that knows how to instantiate an Array[Array[T]]
Produces a ClassTag that knows how to instantiate an Array[Array[T]]
Attributes
Inherited from:
Source
A class representing the type U to which T would be erased.
A class representing the type U to which T would be erased. Note that there is no subtyping relationship between T and U.
Attributes
Inherited from:
Source
Tests whether the type represented by this manifest is a subtype of the type represented by that manifest, subject to the limitations described in the header.
Tests whether the type represented by this manifest is a subtype of the type represented by that manifest, subject to the limitations described in the header.
Attributes
Deprecated
[Since version 2.10.0] use scala.reflect.runtime.universe.TypeTag for subtype checking instead
Inherited from:
Source
ClassManifestDeprecatedApis.scala
Tests whether the type represented by this manifest is a supertype of the type represented by that manifest, subject to the limitations described in the header.
Tests whether the type represented by this manifest is a supertype of the type represented by that manifest, subject to the limitations described in the header.
Attributes
Deprecated
[Since version 2.10.0] use scala.reflect.runtime.universe.TypeTag for subtype checking instead
Inherited from:
Source
ClassManifestDeprecatedApis.scala
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