Access env variable in enum manner -- useful for feature flags based on environment variables

flag_enum_descriptor.py

import os
from enum import Flag
from typing import Any


class EnvFlag: # Descriptor

    def __init__(self, name: str) -> None:
        self.name = name

    def __get__(self, instance: Any, owner: Any) -> bool:
        return bool(os.environ.get(self.name, False))


class FeatureFlag(Flag):
    LOGIN = EnvFlag("LOGIN")

# No LOGIN env variable set
print("No env:", FeatureFlag.LOGIN)
os.environ["LOGIN"] = "1"

print("Env as '1':", FeatureFlag.LOGIN)
os.environ["LOGIN"] = "True"

print("Env as 'True':", FeatureFlag.LOGIN)
os.environ["LOGIN"] = ""

print("Env as '':", FeatureFlag.LOGIN)