def change_period(self, new_period):
self._renew_period = new_period
if self._renew_handle:
Planner.kill_task(self._renew_handle)
self._renew_handle = None
if self._renew_period > 0:
self._renew_handle = Planner.repeat(self._renew_period, self._update_value)
def _add_listener(self, listener):
if not self._listeners and self._renew_period > 0:
self._renew_handle = Planner.repeat(self._renew_period, self._update_value)
self._listeners.append(listener)
self._handle_count += 1
return listener[0]
