gistfile1.txt

Welcome to Scala version 2.10.0-20120503-160535-58f6a13460 (Java HotSpot(TM) 64-Bit Server VM, Java 1.6.0_31).
Type in expressions to have them evaluated.
Type :help for more information.

scala> :paste
// Entering paste mode (ctrl-D to finish)

trait DynamicThis[+T] extends Dynamic {
  this: T =>

  def dynamicMissingMethod(which: String, method: String)(args: Any*): Any
  private def wrap(which: String, method: String)(args: Any*): this.type = {
    dynamicMissingMethod(which, method)(args: _*)
    this
  }
  
  def selectDynamic(method: String): T                           = wrap("selectDynamic", method)()
  def applyDynamic(method: String)(args: Any*): T                = wrap("applyDynamic", method)(args: _*)
  def applyDynamicNamed(method: String)(args: (String, Any)*): T = wrap("applyDynamicNamed", method)(args: _*)
  def updateDynamic(method: String)(args: Any*): T               = wrap("updateDynamic", method)(args: _*)
}

class Accumulator extends DynamicThis[Accumulator] {
  private var calls: List[String] = Nil

  def dynamicMissingMethod(which: String, method: String)(args: Any*) = calls ::= (which match {
    case "selectDynamic"     => method
    case "applyDynamic"      => args.mkString(method + "(", ", ", ")")
    case "applyDynamicNamed" => args.map({ case (k, v) => k + " = " + v }).mkString(method + "(", ", ", ")")
    case "updateDynamic"     => "update (?) "+ args.mkString(method + "(", ", ", ")")
  })

  override def toString = calls.reverse mkString "."
}

// Exiting paste mode, now interpreting.

defined trait DynamicThis
defined class Accumulator

scala> val x = new Accumulator
x: Accumulator = 

scala> x.bippy("hi", "mom").bingo.bong.bong.bong.and(dog = "groucho", cat = "harpo")
res0: Accumulator = bippy(hi, mom).bingo.bong.bong.bong.and(dog = groucho, cat = harpo)