How to compare Enums in Python?

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You should always implement the rich comparison operaters if you want to use them with an Enum. Using the functools.total_ordering class decorator, you only need to implement an __eq__ method along with a single ordering, e.g. __lt__. Since enum.Enum already implements __eq__ this becomes even easier:

>>> import enum
>>> from functools import total_ordering
>>> @total_ordering
... class Grade(enum.Enum):
...   A = 5
...   B = 4
...   C = 3
...   D = 2
...   F = 1
...   def __lt__(self, other):
...     if self.__class__ is other.__class__:
...       return self.value < other.value
...     return NotImplemented
... 
>>> Grade.A >= Grade.B
True
>>> Grade.A >= 3
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unorderable types: Grade() >= int()

Terrible, horrible, ghastly things can happen with IntEnum. It was mostly included for backwards-compatibility sake, enums used to be implemented by subclassing int. From the docs:

For the vast majority of code, Enum is strongly recommended, since
IntEnum breaks some semantic promises of an enumeration (by being
comparable to integers, and thus by transitivity to other unrelated
enumerations). It should be used only in special cases where there’s
no other choice; for example, when integer constants are replaced with
enumerations and backwards compatibility is required with code that
still expects integers.

Here’s an example of why you don’t want to do this:

>>> class GradeNum(enum.IntEnum):
...   A = 5
...   B = 4
...   C = 3
...   D = 2
...   F = 1
... 
>>> class Suit(enum.IntEnum):
...   spade = 4
...   heart = 3
...   diamond = 2
...   club = 1
... 
>>> GradeNum.A >= GradeNum.B
True
>>> GradeNum.A >= 3
True
>>> GradeNum.B == Suit.spade
True
>>>

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