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https://github.com/python/cpython/commit/135ecc3492cee259090fd4aaed9056c130cd2eba
commit: 135ecc3492cee259090fd4aaed9056c130cd2eba
branch: main
author: Raymond Hettinger <rhettinger@users.noreply.github.com>
committer: rhettinger <rhettinger@users.noreply.github.com>
date: 2021-12-03T20:37:08-06:00
summary:

bpo-20751: Replace method example with attribute example, matching the descriptor howto (GH-29909)

files:
M Doc/reference/datamodel.rst

diff --git a/Doc/reference/datamodel.rst b/Doc/reference/datamodel.rst
index b14b2cb1ef5e4..41092458102de 100644
--- a/Doc/reference/datamodel.rst
+++ b/Doc/reference/datamodel.rst
@@ -1818,10 +1818,38 @@ Class Binding
``A.__dict__['x'].__get__(None, A)``.

Super Binding
- If ``a`` is an instance of :class:`super`, then the binding ``super(B, obj).m()``
- searches ``obj.__class__.__mro__`` for the base class ``A``
- immediately following ``B`` and then invokes the descriptor with the call:
- ``A.__dict__['m'].__get__(obj, obj.__class__)``.
+ A dotted lookup such as ``super(A, a).x`` searches
+ ``obj.__class__.__mro__`` for a base class ``B`` following ``A`` and then
+ returns ``B.__dict__['x'].__get__(a, A)``. If not a descriptor, ``x`` is
+ returned unchanged.
+
+.. testcode::
+ :hide:
+
+ class Desc:
+ def __get__(*args):
+ return args
+
+ class B:
+
+ x = Desc()
+
+ class A(B):
+
+ x = 999
+
+ def m(self):
+ 'Demonstrate these two calls are equivalent'
+ result1 = super(A, a).x
+ result2 = B.__dict__['x'].__get__(a, A)
+ return result1 == result2
+
+.. doctest::
+ :hide:
+
+ >>> a = A()
+ >>> a.m()
+ True

For instance bindings, the precedence of descriptor invocation depends on
which descriptor methods are defined. A descriptor can define any combination

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