from RemoteObject import *

class MyThread(threading.Thread):
    """this is a wrapper for threading.Thread that improves
    the syntax for creating and starting threads.  See Appendix A
    of The Little Book of Semaphores, http://greenteapress.com/semaphores/
    """
    def __init__(self, target, *args):
        threading.Thread.__init__(self, target=target, args=args)
        self.start()

class Subject(RemoteObject):
    """A Subject is an object that keeps track of the Observers
    watching it.  When the state of a subject changes, it
    notifies each Observer on the list."""

    def __init__(self):
        RemoteObject.__init__(self)
        self.observers = []

    def notify_observers(self):
        """notify all registered observers when the state of
        the subject changes"""
        for observer in self.observers:
            print 'Notifying', observer
            try:
                observer.notify()
            except:
                pass

    # the following methods are intended to be invoked remotely

    def register(self, name):
        """register a new Observer (invoked by the Observer)"""
        observer = ns.get_proxy(name)
        self.observers.append(observer)

class SimpleSubject(Subject):

    def __init__(self, state=0):
        """The state of a SimpleSubject is a single integer named 'state'
        In a real application, the state would be a more elaborate
        data structure."""
        Subject.__init__(self)
        self.state = 0

    # the following methods are intended to be invoked remotely
        
    def set_state(self, state):
        """change the state of the Subject"""
        print 'New state', state
        self.state = state
        MyThread(self.notify_observers)

    def get_state(self):
        """get the current state of the Subject"""
        return self.state

ns = NameServer()
name = 'bob'
sub = SimpleSubject()
sub.connect(ns, name)
sub.requestLoop()