GIGO: words unreadable aloud

Chapter 7, Exercise 14

Create an abstract class with no methods. Derive a class and add a method. Create a static method that takes a reference to the base class, downcasts it to the derived class, and calls the method. In main(), demonstrate that it works...

package x; 
abstract class Chaos     {                             }
class Blur extends Chaos { def focus = W.rn( "ford" ); }
object c7xI {
    def castor ( cha : Chaos ) = {
        val lens = cha.asInstanceOf[ Blur ];
        lens focus;
    }
    def main ( args: Array[String] ) = {
        val c = new Blur;
        castor( c );
    }
}

... Now put the abstract declaration for the method in the base class, thus eliminating the need for the downcast.

package x; 
abstract class Chaos     { def focus : Unit;           }
class Blur extends Chaos { def focus = W.rn( "ford" ); }
object c7xI_2 {
    def castor ( cha : Chaos ) = {
        cha focus;
    }
    def main ( args: Array[String] ) = {
        val c = new Blur;
        castor( c );
    }
}

11:58:38 PM comment/