Parameterise super class with class member of mixin class

Question

trait Mixin {
    class P
}

abstract class SuperClass[T]

class Impl extends SuperClass[P] with Mixin

Gives:

not found: type P

Is there any way to provide the member class P which is mixed in as the parameter to a super class, or is this impossible because of ordering of evaluation (or some other problem?).

Answer 1

This way the scopes don't work out correctly. But type members and type parameters are nearly equivalent, and if you can make T a member of SuperClass instead, you get

abstract class SuperClass {
  type T
}
// optional
object SuperClass {
  type Aux[T0] = SuperClass { type T = T0 }
}

class Impl extends SuperClass with Mixin {
  type T = P
}

In those cases where you want T to be used as a generic parameter, you use SuperClass.Aux[T].