#!/usr/bin/env python

from copy import deepcopy, copy

class Event():

INIT = "init"

CHANGE = "change"

OPEN = "open"

CLOSE = "close"

ACTIVATE = "activate"

COMPLETE = "complete"

DEACTIVATE = "de_activate"

def __init__( self, type ):

self.type = type

self.target = None

self.data = None

class EventDispatcher():

def __init__(self):

self.map = {}

'''

- Adds an event handler by binding it to an event type

'''

def push_handler( self, type, handler ):

if type not in self.map:

self.map[type] = [ handler ]

else:

self.map[type].append( handler )

'''

- Remove an event handler

'''

def pop_handler( self, type, handler ):

if type in self.map:

handlers = self.map[type]

for h in handlers:

if handler == h:

handlers.remove(h)

'''

- Invoke each handler bound to the dispatched event

- uses deepcopy to handle use case wherein new hanlders are added to

- within other handlers, causing lengths of dictionaries to change and errors to be thrown

'''

def dispatch_event( self, event ):

type = event.type

event.target = self

# -- creating copy to prevent length of handlers from changing if handlers are added within other handlers

clone = deepcopy( self.map )

for type in clone:

handlers = self.map[type]

for handler in handlers:

handler( event )