enums.md

Python by Example: Enums

Enums define a fixed set of named constants. They're type-safe and self-documenting—better than magic numbers or strings. Use them for states, choices, categories, or any fixed set of options. The enum module provides Enum; use IntEnum if you need values that compare with plain integers.

What you'll learn:

• Defining an enum with class Name(Enum):
• Accessing members and values
• Iterating and comparing

from enum import Enum


class Color(Enum):
    RED = 1
    GREEN = 2
    BLUE = 3


print(Color.RED)
print(Color.RED.value)
print(Color(2))


# Iterate
for c in Color:
    print(c.name, c.value)


# Compare by identity
if Color.RED == Color.RED:
    print("Same color")

Color.RED is the enum member; Color.RED.value is 1. Color(2) looks up the member with value 2. Compare enum members with ==; they're singletons.

To run this program:

$ python source/enums.py
Color.RED
1
Color.GREEN
RED 1
GREEN 2
BLUE 3
Same color

Tip: Use enums instead of strings like "red" or numbers like 1 when the set of values is fixed—IDEs and type checkers can help catch errors.

Try it: Create an enum for days of the week and print each.

Source: enums.py

Next: Type Hints