Whistle

Event Dispatcher for Python

Whistle is a simple tool that allow your application components to communicate with each other by dispatching events and listening to them.

Install Documentation

What is Whistle?

Whistle is a lightweight Event Dispatcher library for Python 3.10+ that enables decoupled application communication through event dispatching and listening.

It's largely inspired from Symfony's EventDispatcher component.

Using an event dispatcher is a great way to write loosely coupled extensible code, having each part only communicate using light events, making your code more modular, testable, and maintainable.


Star
Whistle, python's event dispatcher.

Key Features

  • Synchronous and asynchronous dispatching - Choose the right dispatcher for your use case
  • Priority-based listener execution - Control the order listeners run
  • Event propagation control - Stop event flow when needed
  • Type safety - Prevent mixing sync and async listeners
  • Custom events - Attach domain-specific data to events
  • Zero dependencies - Lightweight and easy to integrate

Quick start

Install the whistle package:

 $ pip install whistle

Create an event dispatcher

from whistle import EventDispatcher

dispatcher = EventDispatcher()

Add a listener to react to events

def on_spectacle_starts(event):
    print('Please turn down your phones!')

dispatcher.add_listener('spectacle.starts', on_spectacle_starts)

Or use the decorator syntax for convenience:

@dispatcher.listen('spectacle.starts')
def on_spectacle_starts(event):
    print('Please turn down your phones!')

Dispatch it!

dispatcher.dispatch('spectacle.starts')
# Output: Please turn down your phones!

License

Whistle and the surrounding material (like this website) is licensed under the Apache License, version 2.0.