Call Scala function with explicit default arguments

Question

Is there a way in Scala to explicity tell a function that you want to use the default arguments?

Example

def myFunction(default : Int = 0) { /* logic */ }

myFunction(number match {
    case 5 => 5
    case _ => ???
 })

Is it possible to replace ??? with something that will act as calling the function with the default? (Of course, I could replace with 0, but assume this example for simplicity)

Thanks

chengpohi · Accepted Answer · 2017-06-26 09:45:50Z

3

 number match {
    case 5 => myFunction(5)
    case _ => myFunction()
 }

I think You can do it by using pattern match with function call.

answered Jun 26, 2017 at 9:45

chengpohi

14.2k1 gold badge28 silver badges43 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Bruno Over a year ago

Thanks :) This is the approach I went for.

Jasper-M · Accepted Answer · 2017-06-26 10:00:48Z

The right way is what @chengpohi suggests. The only way to do exactly what you asked is to mess with how scalac implements default arguments under the hood:

myFunction(number match {
  case 5 => 5
  case _ => myFunction$default$1
})

But that is very much not recommended.

Also mind that this will probably not work when pasted without adaptation in the REPL, because the REPL wraps things in additional objects and you'll have to know the absolute path to myFunction$default$1. To test it in the REPL you'll have to wrap it in an object or class:

scala> object Foo {
     |   def myFunction(a: Int = 0) = println(a)
     | 
     |   val number = 42
     |   myFunction(number match {
     |     case 5 => 5
     |     case _ => myFunction$default$1
     |   })
     | }
defined object Foo

scala> Foo
0
res5: Foo.type = Foo$@2035f1f0

Collectives™ on Stack Overflow

Call Scala function with explicit default arguments

2 Answers 2

1 Comment

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Related