Python enum.auto Function

The enum.auto function in Python’s enum module is used to automatically assign values to enumeration members. This is particularly useful when you do not care about the specific values of the enumeration members and want to avoid manually assigning them.

Table of Contents

1. Introduction
2. enum.auto Function Syntax
3. Examples
   • Basic Usage
   • Using enum.auto in IntEnum
   • Combining enum.auto with Custom Methods
4. Real-World Use Case
5. Conclusion

Introduction

The enum.auto function simplifies the process of assigning values to enumeration members. When used, it automatically assigns an integer value starting from 1 and increments by 1 for each subsequent member.

enum.auto Function Syntax

Here is how you use the enum.auto function:

from enum import Enum, auto

class EnumName(Enum):
    MEMBER1 = auto()
    MEMBER2 = auto()
    MEMBER3 = auto()

Parameters:

• EnumName: The name of the enumeration.
• MEMBER: The symbolic name of the enumeration member.

Returns:

• Automatically assigned integer values starting from 1.

Examples

Basic Usage

Define an enumeration with automatic values using enum.auto.

Example

from enum import Enum, auto

class Day(Enum):
    SUNDAY = auto()
    MONDAY = auto()
    TUESDAY = auto()
    WEDNESDAY = auto()
    THURSDAY = auto()
    FRIDAY = auto()
    SATURDAY = auto()

print(Day.SUNDAY)
print(Day.SUNDAY.name)
print(Day.SUNDAY.value)

Output:

Day.SUNDAY
SUNDAY
1

Using enum.auto in IntEnum

Combine enum.auto with IntEnum to create enumerations with automatic integer values.

Example

from enum import IntEnum, auto

class Status(IntEnum):
    ACTIVE = auto()
    INACTIVE = auto()
    PENDING = auto()

print(Status.ACTIVE)
print(Status.ACTIVE.name)
print(Status.ACTIVE.value)

Output:

1
ACTIVE
1

Combining enum.auto with Custom Methods

Use enum.auto with custom methods in an enumeration.

Example

from enum import Enum, auto

class Direction(Enum):
    NORTH = auto()
    SOUTH = auto()
    EAST = auto()
    WEST = auto()

    def is_vertical(self):
        return self in (Direction.NORTH, Direction.SOUTH)

print(Direction.NORTH)
print(Direction.NORTH.name)
print(Direction.NORTH.value)
print(Direction.NORTH.is_vertical())
print(Direction.EAST.is_vertical())

Output:

Direction.NORTH
NORTH
1
True
False

Real-World Use Case

Representing HTTP Status Codes

Use enum.auto to represent HTTP status codes without manually assigning values.

Example

from enum import Enum, auto

class HttpStatus(Enum):
    OK = auto()
    CREATED = auto()
    ACCEPTED = auto()
    NO_CONTENT = auto()
    BAD_REQUEST = auto()
    UNAUTHORIZED = auto()
    FORBIDDEN = auto()
    NOT_FOUND = auto()
    INTERNAL_SERVER_ERROR = auto()

print(HttpStatus.OK)
print(HttpStatus.OK.name)
print(HttpStatus.OK.value)

Output:

HttpStatus.OK
OK
1

Conclusion

The enum.auto function is a convenient tool for automatically assigning values to enumeration members in Python. It simplifies the process of defining enumerations, especially when the specific values of the members are not important. This can improve the readability and maintainability of your code, making it easier to work with enumerations in various scenarios.