cached_property.py

   1 # -*- coding: utf-8 -*-
   2
   3 __author__ = 'Daniel Greenfeld'
   4 __email__ = 'pydanny@gmail.com'
   5 __version__ = '0.1.3'
   6 __license__ = 'BSD'
   7
   8
   9 class cached_property(object):
  10     """ A property that is only computed once per instance and then replaces
  11         itself with an ordinary attribute. Deleting the attribute resets the
  12         property. """
  13
  14     def __init__(self, func):
  15         self.__doc__ = getattr(func, '__doc__')
  16         self.func = func
  17
  18     def __get__(self, obj, cls):
  19         if obj is None:
  20             return self
  21         value = obj.__dict__[self.func.__name__] = self.func(obj)
  22         return value