scala.reflect.ClassTag
See theClassTag companion objectA 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.
AttributesA 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
.
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 parametersthe value being probed for possible equality
true if this instance can possibly equal that
, otherwise false
Checks whether this instance is equal to that
.
Checks whether this instance is equal to that
. This universal equality method is defined in AnyRef
.
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.
the hash code value for this object.
Produces a new array with element type T
and length len
Produces a new array with element type T
and length len
Returns a string representation of the object.
Returns a string representation of the object.
The default representation is platform dependent.
Attributesa string representation of the object.
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]
.
Produces a ClassTag
that knows how to instantiate an Array[Array[T]]
Produces a ClassTag
that knows how to instantiate an Array[Array[T]]
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.
[Since version 2.10.0]
use scala.reflect.runtime.universe.TypeTag for subtype checking instead
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.
[Since version 2.10.0]
use scala.reflect.runtime.universe.TypeTag for subtype checking instead
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