enum

Enum (short for enumeration) is a class in Python used to define a set of named, immutable constants. Enumerations improve code readability and maintainability by replacing magic numbers or strings with meaningful names. Enums are part of Python’s built-in enum module, introduced in Python 3.4.

Note: Magic numbers are unclear, hardcoded values in code. For example, 80 in a speed-checking program might be confusing. Replacing it with an enum constant, like SpeedLimit.HIGHWAY, makes the code easier to read and maintain.

Syntax

from enum import Enum

class EnumName(Enum):
  MEMBER1 = value1
  MEMBER2 = value2

• EnumName: The name of the enum class.
• MEMBER1, MEMBER2: Names of the constants.
• value1, value2: Values assigned to the constants (e.g. numbers or strings).

enum Module

The enum module provides the Enum class for creating enumerations. It also includes:

• IntEnum: Ensures that the values of the enuemration are integers.
• Flag: Allows combining constants with bitwise operations.
• Auto: Automatically assigns values to the enumeration members.

Enums also provide methods like:

• .name: Returns the name of the enum member (as a string).
• .value: Returns the value assigned to the enum member.

Example

This example demonstrates how to create an enum for days of the week with integer values:

from enum import Enum

class Weekday(Enum):
  MONDAY = 1
  TUESDAY = 2
  WEDNESDAY = 3

# Accessing members
print(Weekday.MONDAY)
print(Weekday.MONDAY.name)
print(Weekday.MONDAY.value)

# Iterating through members
for day in Weekday:
  print(day)

This example results in the following output:

Weekday.MONDAY
MONDAY
1
Weekday.MONDAY
Weekday.TUESDAY
Weekday.WEDNESDAY

Codebyte

This example demonstrates how enums can represent traffic light states and associate actions with each state:

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