Scala provide type information in subclassed generic function

Question

Here is my problem.

I have an abstract class that defines a method with type parameters as input and output. I want the subclasses to provide the type information when subclassing but I want to do it in a way that I don't parametrize the whole class.

Some pseudo code of what I'm aiming at.

abstract class A {

  def foo[T](t: T): T

}



class B() extends A {

  override foo[Int](t: Int): Int = t + 1

}



class C() extends A {

  override foo[Double](t: Double): Double = t + 1.0

}

How do I pass the type information on subclassing? I looked at similar problems. They address that with self types, type classes and abstract types.

Thanks

Recommended for you: Get network issues from WhatsUp Gold. Not end users.

Answer 1

As you've said, an abstract type on A can solve that:

abstract class A {
  type T
  def foo(t: T): T
}

class B extends A {
  override type T = Int
  override def foo(t: Int): Int = t + 1
}

class C extends A {
  override type T = Double
  override def foo(t: Double): Double = t + 1.0
}

Scala provide type information in subclassed generic function

Sign up