def get_maintainer(self, graph, handler, target, dispatcher):
""" Return a notifier for maintaining downstream observers when
a dict is mutated.
Parameters
----------
graph : ObserverGraph
Description for the *downstream* observers, i.e. excluding self.
handler : callable
User handler.
target : object
Object seen by the user as the owner of the observer.
dispatcher : callable
Callable for dispatching the handler.
Returns
-------
notifier : ObserverChangeNotifier
"""
return ObserverChangeNotifier(
observer_handler=_observer_change_handler,
event_factory=dict_event_factory,
prevent_event=lambda event: False,
graph=graph,
handler=handler,
target=target,
dispatcher=dispatcher,
)
def get_maintainer(self, graph, handler, target, dispatcher):
""" Return a notifier for maintaining downstream observers when
a trait is changed.
All events should be allowed through, including setting default value
such that downstream observers can be maintained on the new value.
Parameters
----------
graph : ObserverGraph
Description for the *downstream* observers, i.e. excluding self.
handler : callable
User handler.
target : object
Object seen by the user as the owner of the observer.
dispatcher : callable
Callable for dispatching the handler.
Returns
-------
notifier : ObserverChangeNotifier
"""
return ObserverChangeNotifier(
observer_handler=observer_change_handler,
event_factory=trait_event_factory,
prevent_event=lambda event: False,
graph=graph,
handler=handler,
target=target,
dispatcher=dispatcher,
)
def create_notifier(**kwargs):
""" Convenient function for creating an instance of ObserverChangeNotifier
for testing purposes.
"""
values = dict(
graph=mock.Mock(),
observer_handler=mock.Mock(),
event_factory=mock.Mock(),
prevent_event=lambda event: False,
handler=mock.Mock(),
target=mock.Mock(),
dispatcher=dispatch_here,
)
values.update(kwargs)
return ObserverChangeNotifier(**values)