From: Miss Islington (bot) <31488909+miss-islington@users.noreply.github.com>
Date: Mon, 16 Nov 2020 01:52:22 +0000 (-0800)
Subject: bpo-42317: Improve docs of typing.get_args concerning Union (GH-23254)
X-Git-Tag: v3.9.1rc1~45
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=2369759a47c5292bacf2eef17b4e2388b7d36675;p=thirdparty%2FPython%2Fcpython.git

bpo-42317: Improve docs of typing.get_args concerning Union (GH-23254)

(cherry picked from commit c3b9592244a9112d8af9610ff1c4e1e4cd4bfaca)

Co-authored-by: Dominik1123 <15989985+Dominik1123@users.noreply.github.com>
---

diff --git a/Doc/library/typing.rst b/Doc/library/typing.rst
index a5f8b0403f80..324abdeb5eb5 100644
--- a/Doc/library/typing.rst
+++ b/Doc/library/typing.rst
@@ -1687,6 +1687,9 @@ Introspection helpers
    For a typing object of the form ``X[Y, Z, ...]`` these functions return
    ``X`` and ``(Y, Z, ...)``. If ``X`` is a generic alias for a builtin or
    :mod:`collections` class, it gets normalized to the original class.
+   If ``X`` is a :class:`Union` contained in another generic type,
+   the order of ``(Y, Z, ...)`` may be different from the order of
+   the original arguments ``[Y, Z, ...]`` due to type caching.
    For unsupported objects return ``None`` and ``()`` correspondingly.
    Examples::