def notify(self):
"""when the Subject is modified, it invokes notify;
then the Observer uses get_state to see the update.
As a simpler alternative, the Subject could pass the
new state as a parameter."""
print 'Notified'
ns = NameServer()
proxy = ns.get_proxy(self.subject)
print 'Got proxy'
state = proxy.get_state()
print 'Observer notified; new state =', state
def notify(self):
"""when the Subject is modified, it invokes notify;
then the Observer uses get_state to see the update.
As a simpler alternative, the Subject could pass the
new state as a parameter."""
print 'Notified'
ns = NameServer()
proxy = ns.get_proxy(self.subject)
print 'Got proxy'
state = proxy.get_state()
print 'Observer notified; new state =', state
def main(script, to='downey', message='hello', sender='downey', *args):
"""Contact the remote object with the given name and
invoke popup with the given message"""
ns = NameServer()
try:
name = 'popup_%s' % to
server = ns.get_proxy(name)
except Pyro.errors.NamingError:
print "I can't find a remote object named " + name
return
print server.popup(message, sender)
def __init__(self, subject_name):
# connect to the name server
id = random.randint(0, 1000000)
observer_name = subject_name + '_observer%d' % id
RemoteObject.__init__(self, observer_name)
# register with the subject
self.subject = subject_name
ns = NameServer()
proxy = ns.get_proxy(subject_name)
proxy.register(observer_name)
print "I just registered."
def __init__(self, subject_name):
# connect to the name server
id = random.randint(0, 1000000)
observer_name = subject_name + '_observer%d' % id
RemoteObject.__init__(self, observer_name)
# register with the subject
self.subject = subject_name
ns = NameServer()
proxy = ns.get_proxy(subject_name)
proxy.register(observer_name)
print "I just registered."
def notify_observers(self):
"""notify all registered observers when the state of
the subject changes"""
for observer in copy(self.observers):
try:
print "Notifying", observer
ns = NameServer()
proxy = ns.get_proxy(observer)
proxy.notify()
except Exception, x:
# this clause should catch errors that occur
# in the Observer code.
print "".join(Pyro.util.getPyroTraceback(x))
except:
def notify_observers(self):
"""notify all registered observers when the state of
the subject changes"""
for observer in copy(self.observers):
try:
print 'Notifying', observer
ns = NameServer()
proxy = ns.get_proxy(observer)
proxy.notify()
except Exception, x:
# this clause should catch errors that occur
# in the Observer code.
print ''.join(Pyro.util.getPyroTraceback(x))
except:
def notify_observers(self):
"""notify all registered observers when the state of
the subject changes"""
for observer in copy(self.observers):
try:
print 'Notifying', observer
ns = NameServer()
proxy = ns.get_proxy(observer)
proxy.notify()
except Exception as x:
# this clause should catch errors that occur
# in the Observer code.
print ''.join(Pyro.util.getPyroTraceback(x))
except BaseException:
# this clause should catch Pyro NamingErrors,
# which occur when an observer dies.
print 'Removing ' + observer
self.observers.remove(observer)
"""Example of the Observer pattern using Pyro.
Copyright 2010 Allen B. Downey
License: GNU GPLv3 http://www.gnu.org/licenses/gpl.html
"""
import Pyro.errors
from remote_object import NameServer
class Modifier:
"""A Modifier is an object that reads and writes the state of
a Subject, but it is not a registered Observer."""
def __init__(self, subject_name):
self.subject = ns.get_proxy(subject_name)
def modify(self):
"""Increment the state of the Subject."""
state = self.subject.get_state()
self.subject.set_state(state + 1)
print 'Set state ' + str(state + 1)
ns = NameServer()
subject_name = 'simple_subject'
mod = Modifier(subject_name)
mod.modify()
