optional default parameter in scala

Question

I have a function which builds a path like so:

def generatePath(arg1: String, arg2: String, arg3: String* = null) = {
    Array(arg1, arg2, arg3).mkString("/")
}

The function should return something like this:

generatePath("data", "g1")
"data/g1"

generatePath("data", "g1", "hello")
"data/g1/hello"

generatePath("data", "g1", "hello", "world", "yes")
"data/g1/hello/world/yes"

val additionalPaths: Array[String] = Array[String]("yahoo", "awesome")
generatePath("data", "g1", additionalPaths: _*)
"data/g1/yahoo/awesome"

I can't figure out how to get it to work though. I do want it to be so that you can omit arg3, that arg3 can take any number of arguments, or a flattened Seq.

Answer 1

Just remove default value and it will work. String* allows zero-length lists as well.

def generatePath(arg1: String, arg2: String, arg3: String* ) = {
    Array(arg1, arg2, arg3.mkString("/")).mkString("/")
}

println(generatePath("1", "2"))
println(generatePath("1", "2", "3"))
println(generatePath("1", "2", "3", "4"))