77 lines
1.8 KiB
Python
77 lines
1.8 KiB
Python
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"""Class-based event handlers
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A light-weight event-handler framework based on event classes.
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Handlers are registered for event classes:
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>>> import zope.event.classhandler
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>>> class MyEvent(object):
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... pass
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>>> def handler1(event):
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... print("handler1 %r" % event.__class__.__name__)
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>>> zope.event.classhandler.handler(MyEvent, handler1)
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Descriptor syntax:
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>>> @zope.event.classhandler.handler(MyEvent)
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... def handler2(event):
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... print("handler2 %r" % event.__class__.__name__)
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>>> class MySubEvent(MyEvent):
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... pass
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>>> @zope.event.classhandler.handler(MySubEvent)
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... def handler3(event):
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... print("handler3 %r" % event.__class__.__name__)
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Subscribers are called in class method-resolution order, so only
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new-style event classes are supported, and then by order of registry.
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>>> import zope.event
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>>> zope.event.notify(MySubEvent())
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handler3 'MySubEvent'
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handler1 'MySubEvent'
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handler2 'MySubEvent'
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"""
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import zope.event
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__all__ = [
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'handler',
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]
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registry = {}
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def handler(event_class, handler_=None, _decorator=False):
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""" Define an event handler for a (new-style) class.
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This can be called with a class and a handler, or with just a
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class and the result used as a handler decorator.
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"""
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if handler_ is None:
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return lambda func: handler(event_class, func, True)
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if not registry:
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zope.event.subscribers.append(dispatch)
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if event_class not in registry:
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registry[event_class] = [handler_]
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else:
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registry[event_class].append(handler_)
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if _decorator:
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return handler
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def dispatch(event):
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for event_class in event.__class__.__mro__:
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for handler in registry.get(event_class, ()):
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handler(event)
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