Harshal Pandya Harshal Pandya - 2 months ago 15
Scala Question

abstract type pattern is unchecked since it is eliminated by erasure

Could someone tell me how can I avoid the warning in the code block below:

abstract class Foo[T <: Bar]{
case class CaseClass[T <: Bar](t: T)
def method1 = {
case CaseClass(t: T) => println(t)
csse _ =>
}
}


This results in a compiler warning:

abstract type pattern T is unchecked since it is eliminated by erasure
case CaseClass(t: T) => println(t)
^

Answer

You could use ClassTag (or TypeTag):

import scala.reflect.ClassTag

abstract class Foo[T <: Bar : ClassTag]{
  ...
  val clazz = implicitly[ClassTag[T]].runtimeClass
  def method1 = {
    case CaseClass(t) if clazz.isInstance(t) => println(t) // you could use `t.asInstanceOf[T]`
    case _ => 
  }
}