bpo-31672 - Add one last minor clarification for idpattern (#4483)
Add one last minor clarification for idpattern
diff --git a/Lib/string.py b/Lib/string.py
index a3e6d91..fd4b1f7 100644
--- a/Lib/string.py
+++ b/Lib/string.py
@@ -79,11 +79,14 @@
"""A string class for supporting $-substitutions."""
delimiter = '$'
- # r'[a-z]' matches to non-ASCII letters when used with IGNORECASE,
- # but without ASCII flag. We can't add re.ASCII to flags because of
- # backward compatibility. So we use local -i flag and [a-zA-Z] pattern.
+ # r'[a-z]' matches to non-ASCII letters when used with IGNORECASE, but
+ # without the ASCII flag. We can't add re.ASCII to flags because of
+ # backward compatibility. So we use the ?a local flag and [a-z] pattern.
+ # We also can't remove the A-Z ranges, because although they are
+ # technically redundant with the IGNORECASE flag, the value is part of the
+ # publicly documented API.
# See https://bugs.python.org/issue31672
- idpattern = r'(?-i:[_a-zA-Z][_a-zA-Z0-9]*)'
+ idpattern = r'(?a:[_a-zA-Z][_a-zA-Z0-9]*)'
braceidpattern = None
flags = _re.IGNORECASE