A Problem with Combined Enum in Python

Try not to use combined Enum if possible

Image by makbonae on Pixabay

Sometimes we may want to create a combined Enum which includes all the elements of other Enum classes. For example, we may want to create an Enum for the AI models of each AI platform like OpenAI, Gemini, Claude, etc, and use it as a common entry for all the AI models. In this post, we will introduce the problem with such a solution and why we should avoid using it in practice.

Create a combined Enum

In Python, we cannot directly combine two Enum classes in the sense of merging them into a new Enum that contains all members of both. We cannot subclass multiple Enum classes to create a new Enum that inherits members from both either. A feasible solution is to create the combined Enum dynamically using the functional API of Enum.

from enum import IntEnum

class EnumA(IntEnum):
    OPTION_A = 1
    OPTION_B = 2

class EnumB(IntEnum):
    OPTION_C = 3
    OPTION_D = 4

CombinedEnum = IntEnum(
    "CombinedEnum",
    {**EnumA.__members__, **EnumB.__members__},
)

print(EnumA.OPTION_A) # 1
print(EnumB.OPTION_C) # 3
print(CombinedEnum.OPTION_A) # 1
print(CombinedEnum.OPTION_C) # 3

In this solution, we call the Enum class or its subclass which is IntEnum in this example as a function and pass the Enum…