Bringing the elegance of C# EventHandler to Python
The C# language provides a handy way to declare, subscribe to and fire events. Technically, an event is a “slot” where callback functions (event handlers) can be attached to - a process referred to as subscribing to an event. Here is a handy package that encapsulates the core to event subscription and event firing and feels like a “natural” part of the language.
>>> def something_changed(reason): ... print "something changed because %s" % reason ... >>> from events import Events >>> events = Events() >>> events.on_change += something_changed
Multiple callback functions can subscribe to the same event. When the event is fired, all attached event handlers are invoked in sequence. To fire the event, perform a call on the slot:
>>> events.on_change('it had to happen') 'something changed because it had to happen'
By default, Events does not check if an event can be subscribed to and fired. You can predefine events by subclassing Events and listing them. Attempts to subscribe to or fire an undefined event will raise an EventsException.
>>> class MyEvents(Events): ... __events__ = ('on_this', 'on_that', ) >>> events = MyEvents() # this will raise an EventsException as `on_change` is unknown to MyEvents: >>> events.on_change += something_changed
You can also predefine events for a single Events instance by passing an iterator to the constructor.
>>> events = Events(('on_this', 'on_that')) # this will raise an EventsException as `on_change` is unknown to events: >>> events.on_change += something_changed
Complete documentation is available at http://events.readthedocs.org
Events is on PyPI so all you need to do is:
pip install events
python setup.py test
Or use tox to test the package under all supported Pythons: 2.6, 2.7, 3.3, 3.4, 3.5 and 3.6.
Events is BSD licensed. See the LICENSE for details.
Please see the Contribution Guidelines.
Based on the excellent recipe by Zoran Isailovski, Copyright (c) 2005.