PYME.contrib.dispatch.dispatcher module

class PYME.contrib.dispatch.dispatcher.Signal(providing_args=None, use_caching=False)

Bases: object

Base class for all signals

Internal attributes:

receivers

{ receiverkey (id) : weakref(receiver) }

Create a new signal.

connect(receiver, sender=None, weak=True, dispatch_uid=None)

Connect receiver to sender for signal.

Arguments:

receiver

A function or an instance method which is to receive signals. Receivers must be hashable objects.

If weak is True, then receiver must be weak referenceable.

Receivers must be able to accept keyword arguments.

If a receiver is connected with a dispatch_uid argument, it will not be added if another receiver was already connected with that dispatch_uid.

sender

The sender to which the receiver should respond. Must either be a Python object, or None to receive events from any sender.

weak

Whether to use weak references to the receiver. By default, the module will attempt to use weak references to the receiver objects. If this parameter is false, then strong references will be used.

dispatch_uid

An identifier used to uniquely identify a particular instance of a receiver. This will usually be a string, though it may be anything hashable.

disconnect(receiver=None, sender=None, dispatch_uid=None)

Disconnect receiver from sender for signal.

If weak references are used, disconnect need not be called. The receiver will be removed from dispatch automatically.

Arguments:

receiver

The registered receiver to disconnect. May be none if dispatch_uid is specified.

sender

The registered sender to disconnect

dispatch_uid

the unique identifier of the receiver to disconnect

has_listeners(sender=None)

send(sender, **named)

Send signal from sender to all connected receivers.

If any receiver raises an error, the error propagates back through send, terminating the dispatch loop. So it’s possible that all receivers won’t be called if an error is raised.

Arguments:

sender

The sender of the signal. Either a specific object or None.

named

Named arguments which will be passed to receivers.

Return a list of tuple pairs [(receiver, response), … ].

send_robust(sender, **named)

Send signal from sender to all connected receivers catching errors.

Arguments:

sender

The sender of the signal. Can be any Python object (normally one registered with a connect if you actually want something to occur).

named

Named arguments which will be passed to receivers.

Return a list of tuple pairs [(receiver, response), … ].

If any receiver raises an error (specifically any subclass of Exception), return the error instance as the result for that receiver.

PYME.contrib.dispatch.dispatcher.receiver(signal, **kwargs)

A decorator for connecting receivers to signals. Used by passing in the signal (or list of signals) and keyword arguments to connect:

@receiver(post_save, sender=MyModel)
def signal_receiver(sender, **kwargs):
    ...

@receiver([post_save, post_delete], sender=MyModel)
def signals_receiver(sender, **kwargs):
    ...