From: Terry Jan Reedy Date: Tue, 4 May 2021 09:00:29 +0000 (-0400) Subject: bpo-44025: Clarify when '_' is a keyword. (#25873) X-Git-Tag: v3.11.0a1~1215 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=3b200b2aa648fcc8a2673871807c1463afe00195;p=thirdparty%2FPython%2Fcpython.git bpo-44025: Clarify when '_' is a keyword. (#25873) In match statements, in case patterns and nowhere else. Co-authored-by: Jelle Zijlstra --- diff --git a/Doc/reference/compound_stmts.rst b/Doc/reference/compound_stmts.rst index 96bd9b028d50..77400a8d8504 100644 --- a/Doc/reference/compound_stmts.rst +++ b/Doc/reference/compound_stmts.rst @@ -797,7 +797,7 @@ Syntax: capture_pattern: !'_' NAME A single underscore ``_`` is not a capture pattern (this is what ``!'_'`` -expresses). And is instead treated as a :token:`wildcard_pattern`. +expresses). It is instead treated as a :token:`wildcard_pattern`. In a given pattern, a given name can only be bound once. E.g. ``case x, x: ...`` is invalid while ``case [x] | x: ...`` is allowed. @@ -820,7 +820,9 @@ and binds no name. Syntax: .. productionlist:: python-grammar wildcard_pattern: '_' -``_`` is a :ref:`soft keyword `. +``_`` is a :ref:`soft keyword ` within any pattern, +but only within patterns. It is an identifier, as usual, even within +``match`` headers, ``guards``, and ``case`` blocks. In simple terms, ``_`` will always succeed. diff --git a/Misc/NEWS.d/next/Documentation/2021-05-03-22-08-08.bpo-44025.gcB7iP.rst b/Misc/NEWS.d/next/Documentation/2021-05-03-22-08-08.bpo-44025.gcB7iP.rst new file mode 100644 index 000000000000..1432236a32f6 --- /dev/null +++ b/Misc/NEWS.d/next/Documentation/2021-05-03-22-08-08.bpo-44025.gcB7iP.rst @@ -0,0 +1 @@ +Clarify when '_' in match statements is a keyword, and when not.