Scala Generic Subtypes and Cake Pattern - scala

Question

I have the following class hierarchy:
abstract class Event(val timeStamp:Long,val id:Long )
case class StudentEvent(override val timeStamp:Long, override val id:Long,
firstName:String,lastName:String) extends Event(timeStamp,id )
case class TeacherEvent(override val timeStamp:Long, override val id:Long,
firstName:String,lastName:String.....) extends Event(timeStamp,id)
Now I have the following trait:
trait Action[T <: Event] {
def act[T](event:T)
}
Now I would like to extend this trait for students and teachers:
trait StudentAction extends Action[StudentEvent]{
def act(event:StudentEvent) = println(event)
}
trait TeacherAction extends Action[TeacherEvent]{
def act(event:TeacherEvent) = println(event)
}
Now I would like to to create Handler class which take cars for all type of events:
class Handler{
self:Action[Event] =>
def handle(event:Event) = act(event)
}
Now when I try to create Handler for some type of Event, I'm getting compilation error:
val studentHandler = new Handler with StudentAction
illegal inheritance; self-type Handler with StudentAction does not conform to Handler's selftype Handler
with Action[Event]
What am I missing?

Answer 1

Handler type had to be parametrized too:
scala> class Handler[T<:Event] {
| self:Action[T] =>
| def handle(event:T) = act(event)
| }
defined class Handler

Answer 2

#Ashalynd is correct. up voted.
also to extract the inherit logic into a purer code looks like this:
class PARENT
class CHILD extends PARENT
trait A[T <: PARENT]
trait AA extends A[CHILD]
class B[T <: PARENT] {
self: A[T] =>
}
val b = new B[CHILD]() with AA