Given the enum:

classColours(Enum):RED=1

In Python 3.9 and 3.10:

>>>Colours.__dict__["RED"]isColours.REDTrue>>>Colours.RED.RED<Colours.RED:1>

In Python 3.11:

>>>Colours.__dict__["RED"]isColours.REDFalse>>>Colours.RED.REDTraceback (mostrecentcalllast):File"<stdin>",line1,in<module>File"/home/mark/repos/cpython/Lib/enum.py",line198,in__get__raiseAttributeError(^^^^^^^^^^^^^^^^^^^^^AttributeError:<enum'Colours'>memberhasnoattribute'RED'

While these might seem like minor semantic changes, there is also a large performance impact.
Lookup ofColours.RED is simple and efficient in 3.10, but involves a lot of indirection and dispatching through theenum.property class in 3.11.
The performance impact is likely to get worse in 3.12, as we optimize more kinds of attributes.

Introduced inc314e60, I believe.

@pablogsal
@ethanfurman

Linked PRs

• gh-93910: [Enum] remove member.member deprecation #103236
• [3.11] gh-93910: [Enum] remove member.member deprecation (GH-103236) #103299