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celery.utils.dispatch.signal

Signal class.

class celery.utils.dispatch.signal.Signal(providing_args=None)

Base class for all signals

receivers

Internal attribute, holds a dictionary of

`{receriverkey (id): weakref(receiver)}` mappings.

connect(*args, **kwargs)

Connect receiver to sender for signal.

参数:

• 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-referencable (more precisely saferef.safe_ref() must be able to create a reference to the receiver).

  Receivers must be able to accept keyword arguments.

  If receivers have a dispatch_uid attribute, the receiver will not be added if another receiver already exists with that dispatch_uid.

• sender – The sender to which the receiver should respond. Must either be of type Signal, 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, weak=True, 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.

参数:

• receiver – The registered receiver to disconnect. May be none if dispatch_uid is specified.
• sender – The registered sender to disconnect.
• weak – The weakref state to disconnect.
• dispatch_uid – the unique identifier of the receiver to disconnect

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 is quite possible to not have all receivers called if a raises an error.

参数:

• sender – The sender of the signal. Either a specific object or None.
• **named – Named arguments which will be passed to receivers.

返回:

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

send_robust(sender, **named)

Send signal from sender to all connected receivers catching errors.

参数:

• 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. These arguments must be a subset of the argument names defined in providing_args.

返回:

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

引发 DispatcherKeyError:  

if any receiver raises an error (specifically any subclass of Exception), the error instance is returned as the result for that receiver.