Type-hinted events for python, inspired by C# events and delegates.
- Describe events as decorated methods, similar to
@property - Add and remove subscriptions with
+=and-=, like C# events.emitter.on_event += self.respond_to_event
- Subscribed methods are weakly held.
- Subscribed instances will garbage collect automatically without needing to remove all their subscriptions.
- Type hinting, typechecking, and docstring support.
- F2 to rename an event will rename it everywhere.
- Typechecker will verify that you pass the correct args to
.emit(). - Typechecker will verify that subscribers accept the correct args.
For a complete example, see examples/example.py
class Emitter:
# Events are declared by decorating an abstract, *empty* method.
# This method declares the event signature.
@event
def on_change(self, old_value: str, new_value: str): ...
class Observer:
def __init__(self, emitter: Emitter):
emitter.on_change += self.log_change
def log_change(self, old_value: str, new_value: str):
print(f"Value changed from \"{old_value}\" to \"{new_value}\"")
emitter = Emitter()
observer = Observer(emitter)
# Emit with `.emit` or as bare call
emitter.on_change.emit('old', 'new')
emitter.on_change('old', 'new')Not (yet) published to PyPi, so install directly from git using your preferred
package manager. For example, with pip:
pip install git+https://github.com/cspotcode/py_typed_events.gitMicrosoft's doc about the "observer" pattern, which can be implemented with events:
https://learn.microsoft.com/en-us/previous-versions/msp-n-p/ee817669(v=pandp.10)?redirectedfrom=MSDN
Build script uses just: https://github.com/casey/just
Read justfile for details.