Event system

Generic library provides generic.event module which helps you implement event systems in your application. By event system I mean an API for subscribing for some types of events and to handle those events so previously subscribed handlers are being executed.

Basic usage

First you need to describe event types you want to use in your application, generic.event dispatches events to corresponding handlers by inspecting events’ types, so it’s natural to model those as classes:

>>> class CommentAdded(object):
...   def __init__(self, post_id, comment):
...     self.post_id = post_id
...     self.comment = comment

Now you want to register handler for your event type:

>>> from generic.event import Manager

>>> manager = Manager()

>>> @manager.subscriber(CommentAdded)
... def print_comment(ev):
...   print(f"Got new comment: {ev.comment}")

Then you just call generic.event.handle function with CommentAdded instance as its argument:

>>> manager.handle(CommentAdded(167, "Hello!"))
Got new comment: Hello!

This is how it works.

Event inheritance

Using per-application event API

API reference

class generic.event.Manager

Event manager.

Provides API for subscribing for and firing events. There’s also global event manager instantiated at module level with functions subscribe(), handle() and decorator subscriber() aliased to corresponding methods of class.

handle(event: object) None

Fire event

All subscribers will be executed with no determined order.

subscribe(handler: Callable[[object], None], event_type: Type[object]) None

Subscribe handler to specified event_type

subscriber(event_type: Type[object]) Callable[[Callable[[object], None]], Callable[[object], None]]

Decorator for subscribing handlers.

Works like this:

>>> mymanager = Manager()
>>> class MyEvent():
...     pass
>>> @mymanager.subscriber(MyEvent)
... def mysubscriber(evt):
...     # handle event
...     return
>>> mymanager.handle(MyEvent())
unsubscribe(handler: Callable[[object], None], event_type: Type[object]) None

Unsubscribe handler from event_type