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Enums Explained

An enum (enumeration) is a set of named constants. Instead of scattering magic strings like "active", "inactive", "pending" throughout your code, you define them once in an enum and get autocomplete, typo protection, and clear documentation for free.

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Why This Matters

Magic strings and magic numbers are a top source of bugs. If you mistype "actve" instead of "active", Python will not catch it — your code will silently do the wrong thing. Enums make invalid values impossible: Status.ACTVE raises an AttributeError immediately.

Basic enum

from enum import Enum

class Color(Enum):
    RED = "red"
    GREEN = "green"
    BLUE = "blue"

# Usage:
my_color = Color.RED
print(my_color)          # Color.RED
print(my_color.name)     # "RED"
print(my_color.value)    # "red"

Comparing enums

# Use `is` or `==` to compare:
if my_color is Color.RED:
    print("It's red!")

if my_color == Color.RED:
    print("Also red!")

# Enums are NOT equal to their values:
Color.RED == "red"       # False
Color.RED.value == "red" # True

IntEnum — when you need integer values

IntEnum members behave like integers, so you can compare them with numbers and use them in math:

from enum import IntEnum

class Priority(IntEnum):
    LOW = 1
    MEDIUM = 2
    HIGH = 3
    CRITICAL = 4

# Works like an integer:
Priority.HIGH > Priority.LOW     # True
Priority.MEDIUM + 1              # 3
Priority.HIGH == 3               # True (unlike regular Enum)

# Sort by priority:
tasks = [Priority.HIGH, Priority.LOW, Priority.CRITICAL]
sorted(tasks)    # [Priority.LOW, Priority.HIGH, Priority.CRITICAL]

StrEnum — when you need string values (Python 3.11+)

StrEnum members behave like strings:

from enum import StrEnum

class Status(StrEnum):
    ACTIVE = "active"
    INACTIVE = "inactive"
    PENDING = "pending"

# Works like a string:
Status.ACTIVE == "active"        # True
print(f"User is {Status.ACTIVE}")  # "User is active"

# Great for API responses, database values, etc.

If you are on Python 3.10 or earlier, use class Status(str, Enum): instead.

auto() — automatic values

When you do not care about the specific values, let Python assign them:

from enum import Enum, auto

class Direction(Enum):
    NORTH = auto()    # 1
    SOUTH = auto()    # 2
    EAST = auto()     # 3
    WEST = auto()     # 4

auto() assigns incrementing integers starting from 1. Useful when the value does not matter — only the name.

Pattern matching with enums (Python 3.10+)

Enums work beautifully with match/case:

from enum import Enum, auto

class Command(Enum):
    START = auto()
    STOP = auto()
    PAUSE = auto()
    RESUME = auto()

def handle(cmd: Command) -> str:
    match cmd:
        case Command.START:
            return "Starting..."
        case Command.STOP:
            return "Stopping..."
        case Command.PAUSE:
            return "Pausing..."
        case Command.RESUME:
            return "Resuming..."

print(handle(Command.START))    # "Starting..."

Real-world example — HTTP status codes

from enum import IntEnum

class HTTPStatus(IntEnum):
    OK = 200
    CREATED = 201
    BAD_REQUEST = 400
    UNAUTHORIZED = 401
    NOT_FOUND = 404
    SERVER_ERROR = 500

def check_response(status_code: int):
    try:
        status = HTTPStatus(status_code)
    except ValueError:
        print(f"Unknown status: {status_code}")
        return

    if status < 400:
        print(f"{status.name}: Success")
    else:
        print(f"{status.name}: Error")

check_response(200)    # OK: Success
check_response(404)    # NOT_FOUND: Error

Iterating over enums

class Season(Enum):
    SPRING = auto()
    SUMMER = auto()
    AUTUMN = auto()
    WINTER = auto()

# List all members:
for season in Season:
    print(f"{season.name} = {season.value}")

# Get all values:
values = [s.value for s in Season]

# Get all names:
names = [s.name for s in Season]

Looking up enum members

# By name:
Color["RED"]         # Color.RED

# By value:
Color("red")         # Color.RED

# Check membership:
"RED" in Color.__members__    # True

Common Mistakes

Comparing an enum to its value (with regular Enum): 

class Color(Enum):
    RED = "red"

Color.RED == "red"    # False! Use Color.RED.value == "red"

Use StrEnum or IntEnum if you need value comparisons to work naturally.

Forgetting that enum members are singletons: 

# You cannot create new instances with the same value:
Color("red") is Color.RED    # True — same object, not a copy

Trying to modify enum values: 

Color.RED = "crimson"    # AttributeError — enums are immutable

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