StackableTraitAbstractOverride.scala

  trait GeneralTrait {
    def f: Int
  }

  class BaseImpl extends GeneralTrait {
    override def f: Int = 5
  }

  class BaseImpl2 extends GeneralTrait {
    override def f: Int = 50
  }

  trait StackTrait extends GeneralTrait {
    abstract override def f: Int = super.f + 6
  }

  val s1 =  (new BaseImpl).f  //== 5
  val s2= (new BaseImpl with StackTrait).f  //== 11
  val s3=  (new BaseImpl2 with StackTrait).f  //== 56

////////////////////////////////////////////////////////////////////////////
  abstract class BaseClassImpl {
    def f(x:Int): List[Int]
  }

  class MoreImpl extends BaseClassImpl {
    def u: String = "whatever functionality else"
    override def f(x:Int) = List(x)
  }

  trait IncrementList extends BaseClassImpl {
    abstract override def f(x:Int) = {super.f(x) :+ x+1}
  }

  trait DoubleList {
    this:BaseClassImpl =>
    override def f(x:Int) = List(x) :+ x *100
  }

  val n2 = (new MoreImpl).u    //whatever functionality else
  val n21 = (new MoreImpl).f(100)                     // List(100) 
  val n3 = (new MoreImpl with IncrementList).f(100)  //List(100, 101)
  val n3 = (new MoreImpl with DoubleList).f(100)     //List(100, 10000)
 ////////////////////////////////////////////////////////////////////////////////////

  
  

}

//Error: method put in class IntQueue is accessed from super.
// It may not be abstract unless it is overridden by a member declared `abstract' and `override'