static const HitEffect = {
NextHit = nil;
func Hit () {
  // this is the object
  Awesome();
  var fn = this.Hit;
  this.Hit = GetEffect(HitEffect).NextHit;
  var r = this->Hit();
  this.Hit = fn;
  return r;
}
func Start(obj) {
  // this is the effect
  if (obj->GetEffect(HitEffect))
    return obj->RemoveEffect(this);
  NextHit = obj.Hit;
  obj.Hit = Hit;
}
func Stop(obj) {
  // this is the effect
  obj.Hit = NextHit;
}
}
One could probably imagine some library solution that would reduce the boilerplate a bit, but having the engine do the job would be easier. And would work with multiple instances of an effect on the same object. (Though the Real Solution(tm) to that would be closures. With closures one could also reduce the boilerplate to a single function call, at the cost of one wrapper function per callback. Not really worth it...)