in tormenta-core/src/main/scala/com/twitter/tormenta/spout/BaseSpout.scala [32:38]
override def openHook(f: => TopologyContext => Unit) =
new BaseSpout[T] {
override def fieldName = self.fieldName
override def onEmpty = self.onEmpty
override def poll = self.poll
override def callOnOpen = (c: TopologyContext) => { f(c); self.callOnOpen(c) }
}