on 12-Sep-2014 (Fri)

Tags

#odersky-programming-in-scala-2ed #scala

Question

How can you simplify this class?

class ArrayElement(conts: Array[String]) extends Element {
  val contents: Array[String] = conts
}

Answer

Create a parametric field:

class ArrayElement(
  val contents: Array[String]
) extends Element

Tags

#odersky-programming-in-scala-2ed #scala

Question

How come an abstract method can call super? It would certainly fall for classes.

trait Doubling extends IntQueue {
  abstract override def put(x: Int) { super.put(2 * x) }
}

Answer

Since super calls in a trait are dynamically bound, the super call in trait Doubling will work so long as the trait is mixed in after another trait or class that gives a concrete definition to the method.

Tags

#odersky-programming-in-scala-2ed #scala

Question

How can I write import p.n using full import selectors?

Answer

import p.{n}

Tags

#odersky-programming-in-scala-2ed #scala

Question

What does access modifier private[this] mean? Is it more or less restrictive than private ?

Answer

It is more restrictive, because it allows access only from the same object. Same class, different object is not allowed (think: typical implementation of equals() in Java has this.x == that.x; it wouldn't work with private[this] in Scala)