Creating singletons with parameters

Add some point I needed a singleton object, but I also needed to initialze it with specific code. So a standard Scala object wan’t going to help me there since passing parameters to object like this does not compile.

object Singleton(param: String) {

  def foo() = println(param)
}

I decided to go with implicit parameters. First I created the Singleton object and state that the actual thing to be put into foo will be provided implicit (in a rather explicit way, but you can’t have it all).

object Singleton {

  private val foo = implicitly[String](Main.foo)

  def useFoo() = println(foo)
}

And then in Main I declare the implicit and after that the object can be used anywhere.

object Main extends App {

  implicit val foo = "Ain't this cool or what..."

  Singleton.useFoo()
}

And we’re done, another problem solved. Let’s grab a coffee.