Utility code to auto-close resources (e.g. files)

Control.scala

// Control.using is used to automatically close any resource that has a close method
// note: from the book "Beginning Scala" (by David Pollak)
object Control {
  
 	import scala.language.reflectiveCalls
	def using[A <: { def close(): Unit }, B](param: A)(f: A => B): B =
		try {
			f(param)
		} finally {
			param.close()
		}
}

// example of usage
object Test extends App {
  
  import Control._
  def readLines(filename:String):Option[List[String]] = {
    try {
      val lines = using(io.Source.fromFile(filename)) {
    	  source => (for (line <- source.getLines) yield line).toList
      }
    	Some(lines)
    } catch {
      case e: Exception => None
    }
  }

  if (args.length == 1) readLines(args(0)) match {
	  case Some(lines) => println(lines.length + " lines")
    case None => println("No lines")
  }
  else println("No input")
}