+class LazyUUIDTask(object):
+ """
+ A lazy wrapper around Task object, referenced by UUID.
+
+ - Supports comparison with LazyUUIDTask or Task objects (equality by UUIDs)
+ - If any attribute other than 'uuid' requested, a lookup in the
+ backend will be performed and this object will be replaced by a proper
+ Task object.
+ """
+
+ def __init__(self, tw, uuid):
+ self._tw = tw
+ self._uuid = uuid
+
+ def __getitem__(self, key):
+ # LazyUUIDTask does not provide anything else other than 'uuid'
+ if key is 'uuid':
+ return self._uuid
+ else:
+ self.replace()
+ return self[key]
+
+ def __getattr__(self, name):
+ # Getattr is called only if the attribute could not be found using
+ # normal means
+ self.replace()
+ return self.name
+
+ def __eq__(self, other):
+ if other['uuid']:
+ # For saved Tasks, just define equality by equality of uuids
+ return self['uuid'] == other['uuid']
+
+ def __hash__(self):
+ return self['uuid'].__hash__()
+
+ def replace(self):
+ """
+ Performs conversion to the regular Task object, referenced by the
+ stored UUID.
+ """
+
+ replacement = self._tw.tasks.get(uuid=self._uuid)
+ self.__class__ = replacement.__class__
+ self.__dict__ = replacement.__dict__
+
+
+class LazyUUIDTaskSet(object):
+ """
+ A lazy wrapper around TaskQuerySet object, for tasks referenced by UUID.
+
+ - Supports 'in' operator with LazyUUIDTask or Task objects
+ - If iteration over the objects in the LazyUUIDTaskSet is requested, the
+ LazyUUIDTaskSet will be converted to QuerySet and evaluated
+ """
+
+ def __init__(self, tw, uuids):
+ self._tw = tw
+ self._uuids = set(uuids)
+
+ def __getattr__(self, name):
+ # Getattr is called only if the attribute could not be found using
+ # normal means
+ self.replace()
+ return self.name
+
+ def __eq__(self, other):
+ return set(t['uuid'] for t in other) == self._uuids
+
+ def __contains__(self, task):
+ return task['uuid'] in self._uuids
+
+ def __len__(self):
+ return len(self._uuids)
+
+ def __iter__(self):
+ self.replace()
+ for task in self:
+ yield task
+
+ def replace(self):
+ """
+ Performs conversion to the regular TaskQuerySet object, referenced by
+ the stored UUIDs.
+ """
+
+ replacement = self._tw.tasks.filter(' '.join(self._uuids))
+ self.__class__ = replacement.__class__
+ self.__dict__ = replacement.__dict__
+
+