Blinker provides a fast dispatching system that allows any number of interested parties to subscribe to events, or "signals".

Signal receivers can subscribe to specific senders or receive signals sent by any sender.

>>> from blinker import signal
>>> started = signal('round-started')
>>> def each(round):
...     print "Round %s!" % round
...
>>> started.connect(each)

>>> def round_two(round):
...     print "This is round two."
...
>>> started.connect(round_two, sender=2)

>>> for round in range(1, 4):
...     started.send(round)
...
Round 1!
Round 2!
This is round two.
Round 3!

See the Blinker documentation for more information.

Blinker requires Python 2.4 or higher, Python 3.0 or higher, or Jython 2.5 or higher.

1.3 (July 3, 2013)

• The global signal stash behind blinker.signal() is now backed by a regular name-to-Signal dictionary. Previously, weak references were held in the mapping and ephemeral usage in code like signal('foo').connect(...) could have surprising program behavior depending on import order of modules.
• blinker.Namespace is now built on a regular dict. Use blinker.WeakNamespace for the older, weak-referencing behavior.
• Signal.connect('text-sender') uses an alternate hashing strategy to avoid sharp edges in text identity.

1.2 (October 26, 2011)

• Added Signal.receiver_connected and Signal.receiver_disconnected per-Signal signals.
• Deprecated the global 'receiver_connected' signal.
• Verified Python 3.2 support (no changes needed!)

1.1 (July 21, 2010)

• Added @signal.connect_via(sender) decorator
• Added signal.connected_to shorthand name for the temporarily_connected_to context manager.

1.0 (March 28, 2010)

• Python 3.x compatibility

0.9 (February 26, 2010)

• Sphinx docs, project website
• Added with a_signal.temporarily_connected_to(receiver): ... support