# -*- coding: iso-8859-1 -*-
#-----------------------------------------------------------------------------
# Modeling Framework: an Object-Relational Bridge for python
#
# Copyright (c) 2001-2004 Sbastien Bigaret <sbigaret@users.sourceforge.net>
# All rights reserved.
#
# This file is part of the Modeling Framework.
#
# This code is distributed under a "3-clause BSD"-style license;
# see the LICENSE file for details.
#-----------------------------------------------------------------------------
"""
ObserverCenter
Corresponding design patterns: observer+mediator
Instant notification
First invocation on a particular object does notify the observers and is
recorded so that subsequent notifications are discarded. The memory of
already-notified objects can be globally reset by calling
'notifyObserversObjectWillChange' with a 'None' parameter, or on a
per-object base using 'ensureSubsequentChangeWillBeNotifiedForObject'.
Observed object should call
'ObserverCenter.notifyObserversObjectWillChange(self)' to indicate to its
observers that it is about to change.
The ObserverCenter and the interface 'ObservingInterface' are independant
from the framework and can be used alone.
Both observers and observed objects are referenced by weak references
[...more to say here...]
CVS information
$Id: ObserverCenter.py 932 2004-07-20 06:21:57Z sbigaret $
"""
__version__='$Revision: 932 $'[11:-2]
def addObserver(anObserver, anObject):
"""
Resets the 'alreadyNotified' flag
Parameter 'anObserver' should conform to the 'IObserving' interface
"""
def addOmniscientObserver(anObserver):
"""
Parameter 'anObserver' should conform to the 'IObserving' interface
"""
#def enableObserverNotification():
# """
# """
def ensureSubsequentChangeWillBeNotifiedForObject(anObject):
"""
Call this method if you want to make sure the next invocation of
'notifyObserversObjectWillChange' will actually notify observers.
Note that you can achieve the same goal globally by calling
'notifyObserversObjectWillChange' with parameter 'None'.
"""
def notifyObserversObjectWillChange(anObject):
"""
Searches all observers for object 'anObject' and send them the
'objectWillChange' message. Please note that this notification is sent
once and will not be sent upon subsequent request. To reset,
send anObject=None.
Omniscient observers are notified before observers registered for 'anObject'.
Note that any exception that might happen when sending the 'objectWillChange'
message is ignored, hence all observers will receive the message.
"""
#def observerNotificationSuppressCount():
# ""
def observersForObject(anObject):
"""
Returns all observers registered for 'anObject'
"""
def removeObserver(anObserver, anObject):
"""
Removes the supplied 'anObserver' from the list of 'anObject' 's observers.
Parameter 'anObserver' should conform to the 'IObserving' interface.
Silently returns if 'anObserver' cannot be found.
"""
def removeOmniscientObserver(anObserver):
"""
Removes the supplied omniscient observer.
Parameter 'anObserver' should conform to the 'IObserving' interface.
Raises 'ValueError' if 'anObserver' is not a registered omniscient observer.
"""
#def suppressObserverNotification():
# """
# Disables the notification mechanism.
# """
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