`enum`

The Python enum module provides support for enumerations, which are collections of constant values known as members.

Enumerations can improve code readability and maintainability by replacing literal constants and magic numbers with meaningful names.

Here’s how to create an enumeration:

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>>> from enum import Enum

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

>>> Color.RED
<Color.RED: 1>

Key Features

Defines a series of named values
Provides unique names to identify constant values
Supports iteration and comparison

Frequently Used Classes and Functions

Object	Type	Description
`Enum`	Class	Creates enumerations
`IntEnum`	Class	Creates enumerations where members must be integers
`StrEnum`	Class	Creates enumerations where members must be strings
`auto()`	Function	Automatically assigns values to members

Note: The StrEnum class was introduced in Python 3.11. It is not available if you’re using an earlier Python version.

Examples

Defining an enumeration for colors:

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>>> from enum import Enum

>>> class Day(Enum):
...     MONDAY = 1
...     TUESDAY = 2
...     WEDNESDAY = 3
...     THURSDAY = 4
...     FRIDAY = 5
...     SATURDAY = 6
...     SUNDAY = 7
...

Iterating over the members of an enumeration:

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>>> for day in Day:
...     print(day)
...
Day.MONDAY
Day.TUESDAY
Day.WEDNESDAY
Day.THURSDAY
Day.FRIDAY
Day.SATURDAY
Day.SUNDAY

Common Use Cases

Defining a series of related constants with descriptive names
Ensuring constant names are unique and members are immutable
Facilitating comparison operations between related constants

Real-World Example

Suppose you’re developing a traffic light control system and need to define the states of a traffic light. You can use the enum module to create an enumeration for this purpose. Here’s an example:

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>>> from enum import Enum, auto

>>> class TrafficLight(Enum):
...     RED = auto()
...     YELLOW = auto()
...     GREEN = auto()

>>> def can_go(light):
...     return light == TrafficLight.GREEN
...

>>> current_light = TrafficLight.RED
>>> can_go(current_light)
False

In this example, the enum module allows you to define the traffic light states clearly and use them in a function to determine if traffic can proceed, improving code clarity and maintainability.

Tutorial

Build Enumerations of Constants With Python's Enum

In this tutorial, you'll learn how to create and use enumerations of semantically related constants in Python. To do this, you'll use the Enum class and other related tools and types from the enum module, which is available in the Python standard library.

intermediate data-structures python

For additional information on related topics, take a look at the following resources: