[Zope3-checkins] CVS: Zope3/src/zope/app/observable - README.txt:1.1

[Nathan Yergler]

Update of /cvs-repository/Zope3/src/zope/app/observable
In directory cvs.zope.org:/tmp/cvs-serv19954/src/zope/app/observable

Added Files:
	README.txt 
Log Message:


Added simple README for instance-based event subscribers.  Still needs an example or two, I think.


=== Added File Zope3/src/zope/app/observable/README.txt ===
$Id: README.txt,v 1.1 2004/04/02 13:50:04 nathan Exp $

Instance and Based Event Subscription Support

Package Description
===================

This package implements support for subscribing to events for a
particular instance of an object.  This package
implements the proposal found at
http://dev.zope.org/Wikis/DevSite/Projects/ComponentArchitecture/InstanceAndTypeBasedSubscriptions .

The package provides an event channel for dispatching events to the
appropriate instance as well as an adapter from IObservable to
IAnnotatable.  This is important because an object must support
IAnnotatable (and therefore IAnnotations) in order to support
instance-based subscriptions. 

Subscriptions for a particular instance are stored in the instance's
annotations, in a key defined in zope.app.observable.observable.key
(currently 'zope.app.observable').  The annotation stored in the key
is actually an Observers object, which is local registry that is not
aware of the global registry in any way.  More information on the
Observers object is available in observers.txt.