Skip to main content

Zope Event Publication

Project description

The zope.event package provides a simple event system. It provides:

  • An event publishing system

  • A very simple event-dispatching system on which more sophisticated event dispatching systems can be built. (For example, a type-based event dispatching system that builds on zope.event can be found in zope.component.

Detailed Documentation

Events

This package provides a simple event system on which application-specific event systems can be built.

Application code can generate events without being concerned about the event-processing frameworks that might handle the events.

Events are objects that represent something happening in a system. They are used to extend processing by providing processing plug points.

The package has a list of subscribers. Application code can manage subscriptions by manipulating this list. For the examples here, we’ll save the current contents away and empty the list. We’ll restore the contents when we’re done with our examples.

>>> import zope.event
>>> old_subscribers = zope.event.subscribers[:]
>>> del zope.event.subscribers[:]

The package provides a notify function, which is used to notify subscribers that something has happened:

>>> class MyEvent:
...     pass
>>> event = MyEvent()
>>> zope.event.notify(event)

The notify function is called with a single object, which we call an event. Any object will do:

>>> zope.event.notify(None)
>>> zope.event.notify(42)

An extremely trivial subscription mechanism is provided. Subscribers are simply callback functions:

>>> def f(event):
...     print 'got:', event

that are put into the subscriptions list:

>>> zope.event.subscribers.append(f)
>>> zope.event.notify(42)
got: 42
>>> def g(event):
...     print 'also got:', event
>>> zope.event.subscribers.append(g)
>>> zope.event.notify(42)
got: 42
also got: 42

To unsubscribe, simply remove a subscriber from the list:

>>> zope.event.subscribers.remove(f)
>>> zope.event.notify(42)
also got: 42

Generally, application frameworks will provide more sophisticated subscription mechanisms that build on this simple mechanism. The frameworks will install subscribers that then dispatch to other subscribers based on event types or data.

We’re done, so we’ll restore the subscribers:

>>> zope.event.subscribers[:] = old_subscribers

Download

Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Source Distribution

zope.event-1.0.tar.gz (3.7 kB view details)

Uploaded Source

File details

Details for the file zope.event-1.0.tar.gz.

File metadata

  • Download URL: zope.event-1.0.tar.gz
  • Upload date:
  • Size: 3.7 kB
  • Tags: Source
  • Uploaded using Trusted Publishing? No

File hashes

Hashes for zope.event-1.0.tar.gz
Algorithm Hash digest
SHA256 7cb6580b0b743c6596714f669c3223ab1b1dd47b28c1ddb900a20cc6b230eed8
MD5 5de32f8acc8942c1cd7e878dcc6992a8
BLAKE2b-256 150ccaf0cb3d8e3305be980eee50c9442c38cd068cf25566a5b4045df905ac04

See more details on using hashes here.

Supported by

AWS Cloud computing and Security Sponsor Datadog Monitoring Fastly CDN Google Download Analytics Pingdom Monitoring Sentry Error logging StatusPage Status page