policy_module/osm_policy_module/core/singleton.py

   1 """Simple singleton class."""
   2
   3 from __future__ import unicode_literals
   4
   5
   6 class Singleton(object):
   7     """Simple singleton class."""
   8
   9     def __init__(self, decorated):
  10         """Initialize singleton instance."""
  11         self._decorated = decorated
  12
  13     def instance(self):
  14         """Return singleton instance."""
  15         try:
  16             return self._instance
  17         except AttributeError:
  18             self._instance = self._decorated()
  19             return self._instance