抽象类型模式是未选中的,因为它是通过擦除来消除的

Question

有人可以告诉我如何避免下面的代码块中的警告:

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

这会导致编译器警告:

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

Answer 1

你可以使用ClassTag(或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 _ => 
  }
}