Fixed #29478 -- Added support for mangled names to cached_property.

Co-Authored-By: Sergey Fedoseev <fedoseev.sergey@gmail.com>

2 files changed, 44 insertions, 6 deletions

diff --git a/docs/ref/utils.txt b/docs/ref/utils.txt
index 6f529d14fb..06de2731ec 100644
--- a/docs/ref/utils.txt
+++ b/docs/ref/utils.txt
@@ -492,13 +492,19 @@ https://web.archive.org/web/20110718035220/http://diveintomark.org/archives/2004
     database by some other process in the brief interval between subsequent
     invocations of a method on the same instance.
 
-    You can use the ``name`` argument to make cached properties of other
-    methods. For example, if you had an expensive ``get_friends()`` method and
-    wanted to allow calling it without retrieving the cached value, you could
-    write::
+    You can make cached properties of methods. For example, if you had an
+    expensive ``get_friends()`` method and wanted to allow calling it without
+    retrieving the cached value, you could write::
 
         friends = cached_property(get_friends, name='friends')
 
+    You only need the ``name`` argument for Python < 3.6 support.
+
+    .. versionchanged:: 2.2
+
+        Older versions of Django require the ``name`` argument for all versions
+        of Python.
+
     While ``person.get_friends()`` will recompute the friends on each call, the
     value of the cached property will persist until you delete it as described
     above::
@@ -510,8 +516,11 @@ https://web.archive.org/web/20110718035220/http://diveintomark.org/archives/2004
 
     .. warning::
 
-        ``cached_property`` doesn't work properly with a mangled__ name unless
-        it's passed a ``name`` of the form ``_Class__attribute``::
+        .. _cached-property-mangled-name:
+
+        On Python < 3.6, ``cached_property`` doesn't work properly with a
+        mangled__ name unless it's passed a ``name`` of the form
+        ``_Class__attribute``::
 
             __friends = cached_property(get_friends, name='_Person__friends')
 
diff --git a/docs/releases/2.2.txt b/docs/releases/2.2.txt
index aa04b34f0e..02d3fd8682 100644
--- a/docs/releases/2.2.txt
+++ b/docs/releases/2.2.txt
@@ -351,6 +351,35 @@ To simplify a few parts of Django's database handling, `sqlparse
 <https://pypi.org/project/sqlparse/>`_ is now a required dependency. It's
 automatically installed along with Django.
 
+``cached_property`` aliases
+---------------------------
+
+In usage like::
+
+    from django.utils.functional import cached_property
+
+    class A:
+
+        @cached_property
+        def base(self):
+            return ...
+
+        alias = base
+
+``alias`` is not cached. Such usage now raises ``TypeError: Cannot assign the
+same cached_property to two different names ('base' and 'alias').`` on Python
+3.6 and later.
+
+Use this instead::
+
+    import operator
+
+    class A:
+
+        ...
+
+        alias = property(operator.attrgetter('base'))
+
 Miscellaneous
 -------------