如何覆盖 scala 中的泛型方法并用反射调用它

Question

Here is my parent class

sealed trait Conf
sealed case class EmptyConf(value:String) extends Conf

abstract class EntryPoint() {
  def create[C <: Conf](conf: C): Definition
}

Here is the child

class TestEntryPoint extends EntryPoint {
  override def create(conf: EmptyConf): Definition = ???
}

Compiler says:

class TestEntryPoint needs to be abstract, 
since method create in class EntryPoint of type [C <: Conf](conf: C)Definition 
is not defined

What do I do wrong?

UPD: I tried

abstract class EntryPoint[C <: Conf]() {
  def create(conf: C): Definition
}

class TestEntryPoint extends EntryPoint[EmptyConf] {
  override def create(conf: EmptyConf): Definition = ???
}

Then I have troubles instantiating it using reflection.

private def instantiate[P <: EntryPoint[_]](entryPointClass: Class[P],
                                                   conf: Conf): Definition = {
    entryPointClass.getConstructor()
      .newInstance()
      .create(conf)
  }

It won't compile since create expects subclass of Conf . How can I get it in runtime?

UPD: It works, thank you. Just add some bruteforce

entryPointClass.getDeclaredMethods
      .find(_.getName == "create")
      .map(_.invoke(instance, conf))
      .map(_.asInstanceOf[Definition])
      .getOrElse(throw DefinitionInstantiationException(
        s"Can't instantiate ${entryPointClass.getName} " +
          s"using configuration ${conf.getClass.getName}",
        new RuntimeException))

Not type-save though...

Answer 1

It seems that this is what you want

abstract class EntryPoint[C <: Conf]() {
  def create(conf: C): Definition
}

class TestEntryPoint extends EntryPoint[EmptyConf] {
  override def create(conf: EmptyConf): Definition = ???
}