neutron_lib.callbacks.manager module¶

class neutron_lib.callbacks.manager.Callback(id, method, cancellable)¶

Bases: tuple

class neutron_lib.callbacks.manager.CallbacksManager¶

Bases: object

A callback system that allows objects to cooperate in a loose manner.

publish(resource, event, trigger, payload=None)¶

Notify all subscribed callback(s) with a payload.

Dispatch the resource’s event to the subscribed callbacks.

Parameters:

resource – The resource for the event.
event – The event.
trigger – The trigger. A reference to the sender of the event.
payload – The optional event object to send to subscribers. If passed this must be an instance of BaseEvent.

Raises:

neutron_lib.callbacks.exceptions.Invalid – if the payload object is not an instance of BaseEvent.
CallbackFailure – if the underlying callback has errors.

subscribe(callback, resource, event, priority=55550000, cancellable=False)¶

Subscribe callback for a resource event.

The same callback may register for more than one event.

Parameters:

callback – the callback. It must raise or return a boolean.
resource – the resource. It must be a valid resource.
event – the event. It must be a valid event.
priority – the priority. Callbacks are sorted by priority to be called. Smaller one is called earlier.
cancellable – if the callback is “cancellable”, in case of returning an exception, the callback manager will raise a CallbackFailure exception.

unsubscribe(callback, resource, event)¶

Unsubscribe callback from the registry.

Parameters:

unsubscribe_all(callback)¶

Unsubscribe callback for all events and all resources.

unsubscribe_by_resource(callback, resource)¶

Unsubscribe callback for any event associated to the resource.

Parameters:

class neutron_lib.callbacks.manager.PriorityCallbacks(priority, pri_callbacks, cancellable)¶

Bases: tuple

neutron_lib.callbacks.manager module