Question

Is there a way to generically obtain a Scala type’s manifest? For example, if I only have a Class reference to work with, is there a way I can obtain its corresponding manifest?

Answer 1

Scala’s built-in implicitly[T] will get you an implicit value of type T (if one exists). So implicitly[Manifest[T]] will return a Manifest for type T.

If you have a Class reference, you can get the Manifest for the Class like this:

def manifestFor[T: Manifest](c: Class[T]) = implicitly[Manifest[T]]

class Foo
val x =  new Foo
manifestFor(x.getClass)
//scala.reflect.Manifest[_ <: Foo] = _ <: Foo

The Manifest’s type is _ <: Foo instead of just Foo, but they are equal.

implicitly[Manifest[Foo]] == manifestFor(x.getClass)
//Boolean = true