In Scala return value itself for default pattern matching

Question

For value: Any I need to check one string case.
For rest cases should return value itself.
What is the right syntax: case _ => _ ?

def foo(value: Any) = value match {
  case x: String => if (x == "cond") None else x
  case _ => _ // Compiler -> Not found value x$1. Unbound placeholder parameter
}

Answer 1

Simply use some (arbitrary) identifier rather than _:

def foo(value: Any) = value match {
  case x: String => if (x == "cond") None else x
  case other => other
}

However, it is not best practice to return None in some cases, if you're not returning Some in the other cases. A more correct version would be:

def foo(value: Any) = value match {
  case "cond" => None
  case other => Some(other)
}

Then in either case you have an object of type Option.