Question

I have a method like this:

def aMethod(param: String = "asdf") = {
    ...
}

If the method is called as follows, then param is given the default value “asdf”:

aMethod() ...

But what I would like, is that if the method is called with null, then the default value would also be applied:

aMethod(null)  //inside the method, I can use `param` and it has the value "asdf".

Whats the best way to do this in Scala? I can think of pattern matching or a simple if statement.

Answer 1

Pattern matching

def aMethod(param: String = null) {
    val paramOrDefault = param match {
        case null => "asdf"
        case s => s
    }
}

Option (implicitly)

def aMethod(param: String = null) {
    val paramOrDefault = Option(param).getOrElse("asdf")
}

Option (explicitly)

def aMethod(param: Option[String] = None) {
    val paramOrDefault = param getOrElse "asdf"
}

The last approach is actually the most idiomatic and readable once you get use to it.