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

pip install python-dispatch

Usage

For more information, see the documentation here: https://nocarryr.github.io/python-dispatch

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

Metadata

Release files for python-dispatch 0.0.8

For a detailed explanation of source distributions (sdists) and built distributions (wheels), please see the package formats documentation.

Source distribution (sdist)

Source distribution for python-dispatch 0.0.8
File	Size	Uploaded
python-dispatch-0.0.8.tar.gz	9.2 kB	Apr 21, 2017	Details

Built distribution (wheel)

Table of built distributions (wheels) for python-dispatch 0.0.8
File	Interpreter	ABI	Platform	Reset
python_dispatch-0.0.8-py2.py3-none-any.whl 11.4 kB Apr 21, 2017	Python 3, Python 2	none	any	Details

Total release size: 20.6 kB

Release files / python-dispatch-0.0.8.tar.gz

Download URL	python-dispatch-0.0.8.tar.gz
Size	9.2 kB
Tags	Source
SHA-256 checksum How to use checksums	`dfa8a67402977c66e5813385ffc364ace68d9fd8b37fd8bd72f3cff2654c2e04`
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Upload date	Apr 21, 2017
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Release files / python_dispatch-0.0.8-py2.py3-none-any.whl

Download URL	python_dispatch-0.0.8-py2.py3-none-any.whl
Size	11.4 kB
Tags	Python 2 Python 3
SHA-256 checksum How to use checksums	`b2ea5ed792a399f3589279684bfd71d02a2384771e419603dc1e80197392c391`
BLAKE2b-256 checksum How to use checksums	`1aca3545507fc0e87a10901aa301762f2638811eaf3077868e84ba0be7a928ad`
Upload date	Apr 21, 2017
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