events.py

import re

class Event (object):
	message = re.compile("^(?::(?P<prefix>\S+) )?(?P<command>\w+|\d\d\d) (?P<params>.+)$")
	
	def __new__ (cls, line, **kwargs):
		message = cls.message.search(line)
		if message:
			prefix, command, params = message.groups()
			print prefix, command, params
			if command == 'PRIVMSG':
				return PRIVMSG(prefix, params)
			return object.__new__(cls, line, **kwargs)
		else:
			print "Line is not an irc message"
			return None
		
	def __init__ (self, line):
		print "Event created from line '{}'".format(line)

class Message ():
	def __init__ (self, prefix, params):
		print (self.__class__.__name__, prefix, params)

class PRIVMSG (Message):
	pass

print Event('Not_a_valid_irc_message')
print
print Event('PRIVMSG #lambda :Blah blah blah')