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.

handle(event: object) → None¶

Fire event

All subscribers will be executed with no determined order. If a handler raises an exceptions, an ExceptionGroup will be raised containing all raised exceptions.

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