sugar3.dispatch.dispatcher module

class sugar3.dispatch.dispatcher.Signal(providing_args=None)

Bases: object

Base class for all signals

Internal attributes:

receivers – { receriverkey (id) : weakref(receiver) }

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

Connect receiver to sender for signal

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.safeRef() 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.

returns None

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

Disconnect receiver from sender for signal

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

disconnect reverses the process of connect.

If weak references are used, disconnect need not be called.

The receiver will be remove from dispatch automatically.

returns None

send(sender, **named)

Send signal from sender to all connected receivers.

sender – the sender of the signal

Either a specific object or None.

named – named arguments which will be passed to receivers.

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

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.

send_robust(sender, **named)

Send signal from sender to all connected receivers catching errors

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.

Return a list of tuple pairs [(receiver, response), ... ], may raise DispatcherKeyError

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