source: src/Patterns/Observer/Relay.hpp@ 3324cf

/*
 * Relay.hpp
 *
 *  Created on: Dec 1, 2011
 *      Author: heber
 */

#ifndef RELAY_HPP_
#define RELAY_HPP_

// include config.h
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include "Observable.hpp"

/**
 * A Relay acts as a node in a many-to-one observation.
 *
 * All Observable::update() calls will pass through this relay. Hence, if an
 * instance desires to observe all atoms and be notified of each single change,
 * he would otherwise be forced to not only Observable:signon() to each and
 * every one of them but also to keep track of all newly created ones.
 *
 * Instead he simply uses Relay::signOn() of the specific Relay he wishes
 * to use (note Relay should are singleton of nature but are not required to
 * inherit the Singleton pattern) and will get notified as if he were
 * signOn()'ed to each atom because Observer::update() will get passed through
 * the Relay. I.e. the given reference to the Observer points to the atom that
 * initiated the update() call and not to the Relay.
 */
class Relay : public Observable {
public:
  Relay(std::string _name);
  virtual ~Relay();

  virtual void signOn(Observer *target, PriorityLevel priority = Observable::PriorityDefault) const;

  virtual void signOff(Observer *target) const;

  virtual void signOn(Observer *target, size_t channelno) const;

  virtual void signOff(Observer *target, size_t channelno) const;

protected:
  virtual void update(Observable *publisher);
  virtual void recieveNotification(Observable *publisher, Notification_ptr notification);
  virtual void subjectKilled(Observable *publisher);

  virtual void notifyAll();

private:
  //!> Current peer that called last update on us, to be passed on to Observers
  Observable *Updater;
};


#endif /* RELAY_HPP_ */