如何从子类中获取类型化的参数

Question

trait Binding[InternalType, ExternalType]
object BooleanBinding extends Binding[Boolean, String]
class Field(val binding : Binding[_,_], val name : String)
val field = new Field(BooleanBinding, "name")

给出字段，如何获取Binding的InternalType，在这种情况下为Boolean。

Answer 1

您可以通过反射获得类型。由于类型擦除，必须使用TypeTag。

import scala.reflect.runtime.universe._

trait Binding[InternalType, ExternalType]

object BooleanBinding extends Binding[Boolean, String]

class Field[A:TypeTag, B:TypeTag](val binding : Binding[A,B], val name : String) {
  val InternalType = typeOf[A]
  val ExternalType = typeOf[B]
}

private val name = new Field(BooleanBinding, "name")

println(name.InternalType)
// Boolean

println(name.ExternalType)
// String