From d22d97a02d79b22a6ef7618620b06e40afa04287 Mon Sep 17 00:00:00 2001 From: Gouvernathor <44340603+Gouvernathor@users.noreply.github.com> Date: Fri, 1 Mar 2024 16:51:47 +0100 Subject: [PATCH] gh-104219: Document that idunders can return NotImplemented (GH-104220) (cherry picked from commit 2713c2abc8d0f30cd0060cd307bb4ec92f1f04bf) Co-authored-by: Gouvernathor <44340603+Gouvernathor@users.noreply.github.com> Co-authored-by: C.A.M. Gerlach Co-authored-by: Jelle Zijlstra --- Doc/reference/datamodel.rst | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/Doc/reference/datamodel.rst b/Doc/reference/datamodel.rst index 146743221cc1b5..c29c34f2d45111 100644 --- a/Doc/reference/datamodel.rst +++ b/Doc/reference/datamodel.rst @@ -3037,10 +3037,12 @@ left undefined. (``+=``, ``-=``, ``*=``, ``@=``, ``/=``, ``//=``, ``%=``, ``**=``, ``<<=``, ``>>=``, ``&=``, ``^=``, ``|=``). These methods should attempt to do the operation in-place (modifying *self*) and return the result (which could be, - but does not have to be, *self*). If a specific method is not defined, the + but does not have to be, *self*). If a specific method is not defined, or if + that method returns :data:`NotImplemented`, the augmented assignment falls back to the normal methods. For instance, if *x* is an instance of a class with an :meth:`__iadd__` method, ``x += y`` is - equivalent to ``x = x.__iadd__(y)`` . Otherwise, ``x.__add__(y)`` and + equivalent to ``x = x.__iadd__(y)`` . If :meth:`__iadd__` does not exist, or if ``x.__iadd__(y)`` + returns :data:`!NotImplemented`, ``x.__add__(y)`` and ``y.__radd__(x)`` are considered, as with the evaluation of ``x + y``. In certain situations, augmented assignment can result in unexpected errors (see :ref:`faq-augmented-assignment-tuple-error`), but this behavior is in fact