Managed

gistfile1.scala

import io.Source
import java.io.FileWriter


object ManagedDemo extends App{
  import Managed._
  import Managed.{managed => ®}

  for (
    fw <- ®(new FileWriter("target/test-out.txt"));
    fr <- ®(Source.fromFile("build.sbt"))
  ){
    fw.write(fr.mkString)
  }

  println("written:\n"+ ®(Source.fromFile("target/test-out.txt")).map(_.mkString))
}

trait Managed{
  def close() : Unit
}

object Managed{
  implicit def close2Managed[A <: { def close() : Any }](c:A) : Managed = Managed( c.close() )
  implicit def dispose2Managed[A <: { def dispose() : Any   }](c:A) : Managed = Managed( c.dispose() )

  private def apply(closeResource : => Unit) : Managed = new Managed {
    def close() : Unit = closeResource
  }

  def managed[A <% Managed](res: => A) = new Traversable[A]{
    def foreach[U](f: (A) => U) {
      val closable : A = res
      try{
        f(closable)
      }finally{
        closable.close()
      }
    }
  }
}