namespace boost {
  namespace dataflow {
    namespace extension {
      template<typename T> 
        struct component_operation_impl<boost::signals::storage_component_traits< T >, operations::invoke>;
    }
  }
  namespace signals {
    template<typename Signature> class storage_modifier;

    template<typename Storage> struct storage_component_traits;

    template<typename Signature, 
             typename OutSignal = SIGNAL_NETWORK_DEFAULT_OUT, 
             typename SignalArgs = typename default_signal_args<Signature>::type> 
      class storage;
  }
}