This document describes the current stable version of Celery (4.2). For development docs, go here.
Source code for kombu.utils.objects
"""Object Utilities."""
from __future__ import absolute_import, unicode_literals
[docs]class cached_property(object):
"""Cached property descriptor.
Caches the return value of the get method on first call.
Examples:
.. code-block:: python
@cached_property
def connection(self):
return Connection()
@connection.setter # Prepares stored value
def connection(self, value):
if value is None:
raise TypeError('Connection must be a connection')
return value
@connection.deleter
def connection(self, value):
# Additional action to do at del(self.attr)
if value is not None:
print('Connection {0!r} deleted'.format(value)
"""
def __init__(self, fget=None, fset=None, fdel=None, doc=None):
self.__get = fget
self.__set = fset
self.__del = fdel
self.__doc__ = doc or fget.__doc__
self.__name__ = fget.__name__
self.__module__ = fget.__module__
def __get__(self, obj, type=None):
if obj is None:
return self
try:
return obj.__dict__[self.__name__]
except KeyError:
value = obj.__dict__[self.__name__] = self.__get(obj)
return value
def __set__(self, obj, value):
if obj is None:
return self
if self.__set is not None:
value = self.__set(obj, value)
obj.__dict__[self.__name__] = value
def __delete__(self, obj, _sentinel=object()):
if obj is None:
return self
value = obj.__dict__.pop(self.__name__, _sentinel)
if self.__del is not None and value is not _sentinel:
self.__del(obj, value)
return self.__class__(self.__get, fset, self.__del)
return self.__class__(self.__get, self.__set, fdel)