Question

In this blogpost by James Iry, he writes:

Plus, Scala has an “option” method that promotes a value to either Some(value) or None depending on whether it’s null or not …

I can’t seem to find this option method anywhere in the scaladoc.

Iulian Dragos‘s gdata client project contains a method that is probably what James was referring to.

def option[A <: AnyRef](a: A): Option[A] =
  if (a eq null) None else Some(a)

Please point out where can I find this method in the scaladoc.

P.S. I have a method that looks like this:

def permutations(s: String): List[String] = ...

I’m in 2 minds as to whether I should change it to:

def permutations(s: Option[String]): List[String] = ...

since the client can invoke it with null. Currently in the first instance, I expect a String parameter & I box it manually using the option method mentioned previously.

Answer 1

You can simply use the apply factory method on its companion object:

scala> Option.apply("Test")                
res51: Option[java.lang.String] = Some(Test)

scala> Option.apply(null)  
res52: Option[Null] = None

… or the shorter version:

scala> Option("Test")  
res49: Option[java.lang.String] = Some(Test)

scala> Option(null)
res50: Option[Null] = None