Skip to main content
Python Software Foundation 20th Year Anniversary Fundraiser  Donate today!

Simple python event signaling

Project description

smokesignal - simple python signaling

[![Build Status](](

`smokesignal` is a simple python library for sending and receiving signals.
It draws some inspiration from the django signal framework but is meant as a
general purpose variant.

Requirements & Compatibility

`smokesignal` requires no dependencies outside of the python standard library.
It has been tested on and is compatible with python versions 2.6, 2.7, 3.2, and 3.3.

How To Use

Most uses of `smokesignal` involve the functions `on`, which registers a single
method to respond to a signal, and `emit`, which sends a signal. The `on` method can
be used either as a decorator or as a plain function call:

import smokesignal

def my_callback():

smokesignal.on('foo', my_callback)

Once registered, a callback will respond once a signal is emitted:

import smokesignal


Note that `emit` also accepts argument and keyword argument lists that are passed
directly to callbacks. You can also indicate the maximum number of times a callback
should respond to a signal with the `max_calls` keyword argument for `on`, or by using
the `once` method if all you need is for a callback to respond at most once.

If you no longer wish for a callback to respond to any signals, you can use either
`disconnect_from`, if you intend on removing specific signals, or `disconnect` if you intend
to remove all of them:

import smokesignal

# my_callback will no longer respond to signals

# my_callback will no longer respond to 'foo', but may repond to others
smokesignal.disconnect_from(my_callback, 'foo')

Other batteries included:

# Remove all callbacks responding to a specific signal

# Remove all callbacks responding to all signals

# Get a tuple of all signals a callback responds to

# Check if a callback responds to a signal
smokesignal.responds_to(my_callback, 'foo')

Known Issues/Caveats

A major "nice to have" feature of `smokesignal` would be decorated instance methods.
However, that doesn't work for the time being:

import smokesignal

class Foo(object):
def callback(self):

The above does not work because of how `callback` is registered; at the time of registering
it is completely ignorant of any specific instance, so when it is called, it cannot
pass `self` as the first argument. However, there is a bit of a workaround:

import smokesignal

class Foo(object):
def __init__(self, *args, **kwargs):
def _callback():
super(Foo, self).__init__(*args, **kwargs)

def callback(self):

The above will register the callback without any argument requirements but will
also ensure that the _intended_ callback method is called correctly.

Contribution and License
Developed by Shaun Duncan (shaun [dot] duncan [at] gmail [dot] com) and is
licensed under the terms of a MIT license.

Project details

Supported by

AWS AWS Cloud computing Datadog Datadog Monitoring DigiCert DigiCert EV certificate Facebook / Instagram Facebook / Instagram PSF Sponsor Fastly Fastly CDN Google Google Object Storage and Download Analytics Microsoft Microsoft PSF Sponsor Pingdom Pingdom Monitoring Salesforce Salesforce PSF Sponsor Sentry Sentry Error logging StatusPage StatusPage Status page