CODEWITHSUNDEEP
scalavariadic-functions
oxbow_lakes
oxbow_lakes

Reputation: 134270

Using varargs from Scala

I'm tearing my hair out trying to figure out how to do the following:

def foo(msf: String, o: Any, os: Any*) = {
    println( String.format(msf, o :: List(os:_*)) )
}

There's a reason why I have to declare the method with an o and an os Seq separately. Basically, I end up with the format method called with a single object parameter (of type List ). Attempting:

def foo(msf: String, o: Any, os: Any*) = {
    println( String.format(msf, (o :: List(os:_*))).toArray )
}

Gives me the type error:

found: Array[Any]

required Seq[java.lang.Object]

I've tried casting, which compiles but fails for pretty much the same reason as the first example. When I try

println(String.format(msg, (o :: List(os:_*)) :_* ))

this fails to compile with implicit conversion ambiguity (any2ArrowAssoc and any2stringadd)

Upvotes: 55

Views: 48182

Answers (2)

Daniel C. Sobral
Daniel C. Sobral

Reputation: 297165

def foo(msf: String, o: AnyRef, os: AnyRef*) =
  println( String.format(msf, o :: os.toList : _* ) )

or

def foo(msf: String, o: AnyRef, os: AnyRef*) =
      println( msf format (o :: os.toList : _* ) )

I much prefer the latter, though it has no locale* support.

  • Scala 2.8 does have locale support with RichString's format.

Upvotes: 13

James Iry
James Iry

Reputation: 19367

def foo(msf: String, o: AnyRef, os: AnyRef*) = 
  println( String.format(msf, (o :: os.toList).toArray : _* ))

Upvotes: 67

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