From: Miss Islington (bot) <31488909+miss-islington@users.noreply.github.com> Date: Thu, 22 Sep 2022 18:17:30 +0000 (-0700) Subject: gh-96397: Document that keywords in calls need not be identifiers (GH-96393) X-Git-Tag: v3.10.8~114 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=8a2afd295b77cebe940b9772d55243a6f7186ed9;p=thirdparty%2FPython%2Fcpython.git gh-96397: Document that keywords in calls need not be identifiers (GH-96393) This represents the official SC stance, see https://github.com/python/steering-council/issues/142GH-issuecomment-1252172695 (cherry picked from commit 9d432b4a181cd42017699de4354e7b36c5b87d88) Co-authored-by: Jeff Allen --- diff --git a/Doc/reference/expressions.rst b/Doc/reference/expressions.rst index b8c8d5fe3e33..0a9e7141d397 100644 --- a/Doc/reference/expressions.rst +++ b/Doc/reference/expressions.rst @@ -1049,10 +1049,20 @@ used in the same call, so in practice this confusion does not arise. If the syntax ``**expression`` appears in the function call, ``expression`` must evaluate to a :term:`mapping`, the contents of which are treated as -additional keyword arguments. If a keyword is already present -(as an explicit keyword argument, or from another unpacking), +additional keyword arguments. If a parameter matching a key has already been +given a value (by an explicit keyword argument, or from another unpacking), a :exc:`TypeError` exception is raised. +When ``**expression`` is used, each key in this mapping must be +a string. +Each value from the mapping is assigned to the first formal parameter +eligible for keyword assignment whose name is equal to the key. +A key need not be a Python identifier (e.g. ``"max-temp °F"`` is acceptable, +although it will not match any formal parameter that could be declared). +If there is no match to a formal parameter +the key-value pair is collected by the ``**`` parameter, if there is one, +or if there is not, a :exc:`TypeError` exception is raised. + Formal parameters using the syntax ``*identifier`` or ``**identifier`` cannot be used as positional argument slots or as keyword argument names.