From b88abd684041ffa66bfe445e1ac26164e803d488 Mon Sep 17 00:00:00 2001
From: Tomek Paczkowski <tomek@hauru.eu>
Date: Sat, 23 Feb 2013 23:20:00 +0100
Subject: [PATCH] Fixed #19872
Made cached_property to behave as property when accessed via class.
---
django/utils/functional.py | 4 +++-
tests/regressiontests/utils/functional.py | 29 ++++++++++++++++++++++-
2 files changed, 31 insertions(+), 2 deletions(-)
diff --git a/django/utils/functional.py b/django/utils/functional.py
index 1b5200c98c..51001ea655 100644
--- a/django/utils/functional.py
+++ b/django/utils/functional.py
@@ -39,7 +39,9 @@ class cached_property(object):
def __init__(self, func):
self.func = func
- def __get__(self, instance, type):
+ def __get__(self, instance, type=None):
+ if instance is None:
+ return self
res = instance.__dict__[self.func.__name__] = self.func(instance)
return res
diff --git a/tests/regressiontests/utils/functional.py b/tests/regressiontests/utils/functional.py
index 90a6f08630..3bb50007c6 100644
--- a/tests/regressiontests/utils/functional.py
+++ b/tests/regressiontests/utils/functional.py
@@ -1,5 +1,5 @@
from django.utils import unittest
-from django.utils.functional import lazy, lazy_property
+from django.utils.functional import lazy, lazy_property, cached_property
class FunctionalTestCase(unittest.TestCase):
@@ -37,3 +37,30 @@ class FunctionalTestCase(unittest.TestCase):
self.assertRaises(NotImplementedError, lambda: A().do)
self.assertEqual(B().do, 'DO IT')
+
+ def test_cached_property(self):
+ """
+ Test that cached_property caches its value,
+ and that it behaves like a property
+ """
+
+ class A(object):
+
+ @cached_property
+ def value(self):
+ return 1, object()
+
+ a = A()
+
+ # check that it is cached
+ self.assertEqual(a.value, a.value)
+
+ # check that it returns the right thing
+ self.assertEqual(a.value[0], 1)
+
+ # check that state isn't shared between instances
+ a2 = A()
+ self.assertNotEqual(a.value, a2.value)
+
+ # check that it behaves like a property when there's no instance
+ self.assertIsInstance(A.value, cached_property)