In Scala, how do you define a local parameter in the primary constructor of a class?

Question

In Scala, how does one define a local parameter in the primary constructor of a class that is not a data member and that, for example, serves only to initialize a data membe

Answer 1

After some experimentation, I determined that simply leaving out var or val in front of the parameter b will make it a local parameter and not a data member:

class A(var a: Int)
class B(b: Int) extends A(b)

Java expansion:

$ javap -private B
Compiled from "construct.scala"
public class B extends A implements scala.ScalaObject{
    public B(int);
}

$ javap -private A
Compiled from "construct.scala"
public class A extends java.lang.Object implements scala.ScalaObject{
    private int a;
    public A(int);
    public void a_$eq(int);
    public int a();
    public int $tag()       throws java.rmi.RemoteException;
}

Notice that class A has a private data member a due to the var a: Int in its primary constructor. Class B, however, has no data members, but its primary constructor still has a single integer parameter.