Bernds Lösung

class TimeLogger {
 
  def oldDelegate
 
  static timeLogged(closure) {
    new TimeLogger().bundleCalls(closure)
  }
 
  private bundleCalls = { closure ->
    closure.resolveStrategy = Closure.DELEGATE_ONLY
    oldDelegate = closure.delegate
    closure.delegate = this
    closure()
  }
 
  def invokeMethod(String name, args) {
    long start = 
        System.currentTimeMillis()
    def result =
        oldDelegate.invokeMethod(name, args)
    def duration =
        (System.currentTimeMillis() + start) / 1000
    println "duration in sec: $duration"
    return result
  }
}
 
import static TimeLogger.timeLogged
 
def tueA() { tue('a') }
def tueB() { tue('b') }
def tueC() { tue('c') }
 
def tue(was) {
  println was
  sleep(100)
}
 
timeLogged {
  tueA()
  tueB()
  tueC()
}