https://github.com/python/cpython/commit/d4a8066c82a9b71c26d98c285db233fe2ef07517
commit: d4a8066c82a9b71c26d98c285db233fe2ef07517
branch: main
author: Bernát Gábor <[email protected]>
committer: ethanfurman <[email protected]>
date: 2026-06-04T12:58:20-07:00
summary:
gh-150817: Speed up Flag bitwise operations (GH-150824)
Flag.__or__, __and__ and __xor__ walked both operands on every call to reject
None values. Run that scan only when one of the operand values is actually
None, so valid combinations skip it. The TypeError and its message are
unchanged for the invalid cases.
files:
A Misc/NEWS.d/next/Library/2026-06-02-15-44-57.gh-issue-150817.lpFCh0.rst
M Lib/enum.py
diff --git a/Lib/enum.py b/Lib/enum.py
index f97a5193492e60..7aff36c94ce1dc 100644
--- a/Lib/enum.py
+++ b/Lib/enum.py
@@ -1620,10 +1620,14 @@ def __or__(self, other):
if other_value is NotImplemented:
return NotImplemented
- for flag in self, other:
- if self._get_value(flag) is None:
- raise TypeError(f"'{flag}' cannot be combined with other flags
with |")
value = self._value_
+ # _get_value(self) is self._value_ and _get_value(other) is
+ # other_value, so only walk the operands (to raise on the offending
+ # flag) when one of those values is actually None.
+ if value is None or other_value is None:
+ for flag in self, other:
+ if self._get_value(flag) is None:
+ raise TypeError(f"'{flag}' cannot be combined with other
flags with |")
return self.__class__(value | other_value)
def __and__(self, other):
@@ -1631,10 +1635,11 @@ def __and__(self, other):
if other_value is NotImplemented:
return NotImplemented
- for flag in self, other:
- if self._get_value(flag) is None:
- raise TypeError(f"'{flag}' cannot be combined with other flags
with &")
value = self._value_
+ if value is None or other_value is None:
+ for flag in self, other:
+ if self._get_value(flag) is None:
+ raise TypeError(f"'{flag}' cannot be combined with other
flags with &")
return self.__class__(value & other_value)
def __xor__(self, other):
@@ -1642,10 +1647,11 @@ def __xor__(self, other):
if other_value is NotImplemented:
return NotImplemented
- for flag in self, other:
- if self._get_value(flag) is None:
- raise TypeError(f"'{flag}' cannot be combined with other flags
with ^")
value = self._value_
+ if value is None or other_value is None:
+ for flag in self, other:
+ if self._get_value(flag) is None:
+ raise TypeError(f"'{flag}' cannot be combined with other
flags with ^")
return self.__class__(value ^ other_value)
def __invert__(self):
diff --git
a/Misc/NEWS.d/next/Library/2026-06-02-15-44-57.gh-issue-150817.lpFCh0.rst
b/Misc/NEWS.d/next/Library/2026-06-02-15-44-57.gh-issue-150817.lpFCh0.rst
new file mode 100644
index 00000000000000..42532bb0222cf4
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2026-06-02-15-44-57.gh-issue-150817.lpFCh0.rst
@@ -0,0 +1,2 @@
+Speed up the ``|``, ``&`` and ``^`` operations on :class:`enum.Flag` members.
+Patch by Bernát Gábor.
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