== What Are Signals? ==

Signals allow you to make Django call custom methods after common actions using a dispatcher. Beyond that, I really don't know much else. Please help expand this documentation, if you can.

The author of Zyons [http://feh.holsman.net/articles/2006/06/13/django-signals talks about signals a bit here].

== Example ==

The following is taken from [http://zyons.com/ Zyons], the only place I've seen signals used so far. Unless I'm completely incorrect, the following code has the dispatcher call "increment_tag_summary" before a TagUserObject object is saved, and "decrement_tag_summary" after a TagUserObject object is deleted.

=== models.py ===

{{{
from django.db.models import signals
from django.dispatch import dispatcher

[...]

def increment_tag_summary(sender, instance, signal, *args, **kwargs):
    [...]

def decrement_tag_summary(sender, instance, signal, *args, **kwargs):
    [...]

dispatcher.connect( increment_tag_summary , signal=signals.pre_save, sender=TagUserObject )
dispatcher.connect( decrement_tag_summary , signal=signals.post_delete, sender=TagUserObject )
}}}