Speed-up building enums by value, e.g. http.HTTPStatus(200) (#11318)
bpo-35585: Speed up enum by-value lookup
diff --git a/Lib/enum.py b/Lib/enum.py
index fec1aed..f7452f0 100644
--- a/Lib/enum.py
+++ b/Lib/enum.py
@@ -563,8 +563,10 @@
# by-value search for a matching enum member
# see if it's in the reverse mapping (for hashable values)
try:
- if value in cls._value2member_map_:
- return cls._value2member_map_[value]
+ return cls._value2member_map_[value]
+ except KeyError:
+ # Not found, no need to do long O(n) search
+ pass
except TypeError:
# not there, now do long search -- O(n) behavior
for member in cls._member_map_.values():