From 0d7cf26a25da130ee4b11cee85f5394ccec5b40d Mon Sep 17 00:00:00 2001 From: Victorien <65306057+Viicos@users.noreply.github.com> Date: Tue, 12 May 2026 04:45:51 +0200 Subject: [PATCH] gh-148669: Clarify `__reduce__()` module lookup behavior (GH-148670) (cherry picked from commit 54a5fd4126df74f7b84d1f8a6a36ef79803f66f9) Co-authored-by: Victorien <65306057+Viicos@users.noreply.github.com> --- Doc/library/pickle.rst | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/Doc/library/pickle.rst b/Doc/library/pickle.rst index 02b79a9f3a7a47..efae4910ca4358 100644 --- a/Doc/library/pickle.rst +++ b/Doc/library/pickle.rst @@ -59,7 +59,7 @@ The :mod:`!pickle` module differs from :mod:`marshal` in several significant way * :mod:`marshal` cannot be used to serialize user-defined classes and their instances. :mod:`!pickle` can save and restore class instances transparently, however the class definition must be importable and live in the same module as - when the object was stored. + when the object was pickled. * The :mod:`marshal` serialization format is not guaranteed to be portable across Python versions. Because its primary job in life is to support @@ -696,7 +696,10 @@ or both. If a string is returned, the string should be interpreted as the name of a global variable. It should be the object's local name relative to its module; the pickle module searches the module namespace to determine the - object's module. This behaviour is typically useful for singletons. + object's module: for a given ``obj`` to be pickled, the ``__module__`` + attribute is looked up on ``obj`` directly, which falls back to a lookup + on the type of ``obj`` if no ``__module__`` instance attribute is set. + This behaviour is typically useful for singletons. When a tuple is returned, it must be between two and six items long. Optional items can either be omitted, or ``None`` can be provided as their