Python Enum: A Comprehensive Guide with Examples

Introduction to Python Enums

Enums, short for enumerations, provide a convenient and organized way to define a set of named constants. Python enum is a powerful feature that allows you to define such sets of names with unique values. In this guide, we'll cover the basics and advanced aspects of Python enums with clear examples.

Creating Enums in Python

To create a Python enum, you'll need to import the Enum class from the `enum` module. After that, you can define your enum class by subclassing the Enum class and defining the constants within it.

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

Interacting with Enums

Now that we've created our Color Enum, we can interact with its members. We can access individual constants using dot notation and perform various operations, such as comparison and iteration.

print(Color.RED)          # Output: Color.RED
print(Color.BLUE == 3)    # Output: False
print(Color.GREEN.name)   # Output: 'GREEN'
print(Color.RED.value)    # Output: 1

We can also iterate through all the constants of an enum.

for color in Color:
    print(color)

Advanced Python Enums

Python Enums offer certain advanced features, such as aliasing, auto number generation, and custom methods or attributes. Let's look at some examples of using these features.

Here's an example of using the `auto()` function to generate unique values automatically.

from enum import Enum, auto
class Direction(Enum):
    NORTH = auto()
    SOUTH = auto()
    EAST = auto()
    WEST = auto()

Another advanced feature is aliasing, where two constants can have the same value. Let's define a new enum called Shape with aliases.

class Shape(Enum):
    SQUARE = 1
    RECTANGLE = 1
    CIRCLE = 2

We can also create custom methods and attributes within enums.

class Day(Enum):
    MONDAY = 1
    TUESDAY = 2
    WEDNESDAY = 3
    # ... other days

    def is_weekday(self):
        return self.value < 6

Conclusion