Python Dispatch¶
python-dispatch¶
Lightweight event handling for Python
Description¶
This is an implementation of the “Observer Pattern” with inspiration from the Kivy framework. Many of the features though are intentionally stripped down and more generalized. The goal is to have a simple drop-in library with no dependencies that stays out of the programmer’s way.
Installation¶
“python-dispatch” is available on PyPI and can be installed using pip:
pip install python-dispatch
Python Requirements¶
After version 0.1
of this project, only Python 3.6 and above will be supported.
If using an older Python version, the older releases should still be available
on PyPI and the correct package should be chosen automatically by pip
.
If not, either upgrade pip
and setuptools
:
pip install -U pip setuptools
Or specify the version manually:
pip install python-dispatch<0.2
Links¶
Project Home | https://github.com/nocarryr/python-dispatch |
PyPI | https://pypi.python.org/pypi/python-dispatch |
Documentation | https://python-dispatch.readthedocs.io |
Usage¶
Events¶
from pydispatch import Dispatcher
class MyEmitter(Dispatcher):
# Events are defined in classes and subclasses with the '_events_' attribute
_events_ = ['on_state', 'new_data']
def do_some_stuff(self):
# do stuff that makes new data
data = self.get_some_data()
# Then emit the change with optional positional and keyword arguments
self.emit('new_data', data=data)
# An observer - could inherit from Dispatcher or any other class
class MyListener(object):
def on_new_data(self, *args, **kwargs):
data = kwargs.get('data')
print('I got data: {}'.format(data))
def on_emitter_state(self, *args, **kwargs):
print('emitter state changed')
emitter = MyEmitter()
listener = MyListener()
emitter.bind(on_state=listener.on_emitter_state)
emitter.bind(new_data=listener.on_new_data)
emitter.do_some_stuff()
# >>> I got data: ...
emitter.emit('on_state')
# >>> emitter state changed
Properties¶
from pydispatch import Dispatcher, Property
class MyEmitter(Dispatcher):
# Property objects are defined and named at the class level.
# They will become instance attributes that will emit events when their values change
name = Property()
value = Property()
class MyListener(object):
def on_name(self, instance, value, **kwargs):
print('emitter name is {}'.format(value))
def on_value(self, instance, value, **kwargs):
print('emitter value is {}'.format(value))
emitter = MyEmitter()
listener = MyListener()
emitter.bind(name=listener.on_name, value=listener.on_value)
emitter.name = 'foo'
# >>> emitter name is foo
emitter.value = 42
# >>> emitter value is 42
Contributing¶
Contributions are welcome!
If you want to contribute through code or documentation, please see the Contributing Guide for information.
License¶
This project is released under the MIT License. See the LICENSE file for more information.