# .NET-style events in Python.
import time
import thread
from datetime import datetime
class Event():
	def __init__(self):
		self.event_handlers = []
	def add_handler(self, event_handler):
		self.event_handlers.append(event_handler)
	def remove_handler(self, event_handler):
		self.event_handlers.remove(event_handler)
	def raise_event(self, sender, eventArgs):
		for handler in self.event_handlers:
			thread.start_new_thread(handler, (sender, eventArgs))

class EventArgs():
	@property
	def empty(self):
		if not __empty:
			__empty = EventArgs()
		return __empty
	empty = staticmethod(empty)

class FireAlarmActivatedEventArgs(EventArgs):
	def __get_time(self):
		return self.time
	def __get_room(self):
		return self.room
	time = property(fget=__get_time)
	room = property(fget=__get_room)
	def __init__(self, time, room):
		self.time = time
		self.room = room

class Building:
	@property
	def fire_alarm_activated(self):
		return self.__fire_alarm_activated
	def __init__(self):
		self.__fire_alarm_activated = Event()
	def start_fire(self):
		print "It burns, it burns."
		self.fire_alarm_activated.raise_event(
			self, FireAlarmActivatedEventArgs(datetime.now(), 303))
	def evacuate(self):
		print "Evacuating building %s." % (id(self))

class Program:
	def __init__(self):
		self.building = Building()
	def on_fire_alarm_activated(self, sender, eventArgs):
		print "Fire detected in building %s, room %s, at %s" % (
			id(sender), eventArgs.room, eventArgs.time)
		print "Calling fire department."
		sender.evacuate()
	def main(self, *args):
		print "\n"
		self.building.fire_alarm_activated.add_handler(
			self.on_fire_alarm_activated)
		self.building.start_fire()
		time.sleep(0.1)
		print "\n"

Program().main()