🎯 Python Enum, IntEnum, StrEnum – Guide with Examples

🧲 Introduction – Why Use Enums in Python?

In many applications, you need a set of named constant values—for example, days of the week, status codes, or user roles.

Instead of using plain strings or integers, Python’s enum module helps you:

• Define human-readable constant values
• Ensure uniqueness and safety
• Group related values under one class

🎯 In this guide, you’ll learn:

• What Enums are and how they work
• How to create and access Enum members
• Enum types: Enum, IntEnum, StrEnum
• Best practices and common pitfalls

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✅ What Is an Enum?

An Enum (Enumeration) is a class that contains a set of constant members, each with a unique name and value.

Enums improve readability, safety, and code structure.

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🔧 How to Define a Python Enum

➤ Import Enum from the enum module:

from enum import Enum

class Status(Enum):
    PENDING = 1
    APPROVED = 2
    REJECTED = 3

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✅ Accessing Enum Members

print(Status.PENDING)        # Status.PENDING
print(Status.PENDING.name)   # PENDING
print(Status.PENDING.value)  # 1

💡 Enums are class members with unique name and value.

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🧪 Iterating Over Enum Members

for status in Status:
    print(status.name, status.value)

✅ Output:

PENDING 1  
APPROVED 2  
REJECTED 3

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🔄 Comparison and Identity

if Status.APPROVED == Status(2):
    print("Approved!")

💡 You can compare enums by value or by identity (is keyword).

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🔢 Using IntEnum (Supports Integer Comparison)

from enum import IntEnum

class Priority(IntEnum):
    LOW = 1
    MEDIUM = 2
    HIGH = 3

print(Priority.HIGH > Priority.LOW)  # ✅ True

✅ IntEnum members are compatible with integers in comparisons.

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🆕 Python 3.11+: StrEnum for String Comparison

from enum import StrEnum

class Color(StrEnum):
    RED = "red"
    GREEN = "green"
    BLUE = "blue"

print(Color.RED == "red")  # ✅ True

💡 Great when working with APIs or string-based configs.

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📦 Real-World Example – User Roles

from enum import Enum

class Role(Enum):
    ADMIN = "admin"
    MODERATOR = "moderator"
    USER = "user"

def has_permission(role):
    if role == Role.ADMIN:
        return True
    return False

print(has_permission(Role.ADMIN))     # True
print(has_permission(Role.USER))      # False

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❌ Common Pitfalls with Enums

Mistake	Why It’s a Problem	Fix
Using plain strings for states	Leads to typos and inconsistency	Use Enums
Comparing enum to string directly	Enum != "VALUE" unless using StrEnum	Use Enum.value or StrEnum
Creating duplicate values without care	Can cause logical errors	Use @unique decorator

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🧼 Enforcing Unique Values with @unique

from enum import Enum, unique

@unique
class Status(Enum):
    ACTIVE = 1
    INACTIVE = 2
    # ACTIVE = 2  ❌ would raise ValueError

✅ Ensures no duplicate values in your Enum.

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📘 Best Practices

✅ Do This	❌ Avoid This
Use Enums for related constants	Scattering constants across code
Prefer StrEnum/IntEnum when needed	Comparing enum with incompatible types
Name Enums with PascalCase	Using lowercase enum class names
Use @unique for validation	Allowing silent duplicates

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📌 Summary – Recap & Next Steps

Enums in Python provide a structured, readable, and type-safe way to manage constants. They are a great replacement for primitive values in status codes, roles, and configuration flags.

🔍 Key Takeaways:

• ✅ Use Enums to define named constants
• ✅ Access with .name, .value, and loop with for
• ✅ Use IntEnum for numeric comparison
• ✅ Use StrEnum (Python 3.11+) for string matching
• ✅ Validate uniqueness with @unique

⚙️ Real-World Relevance:
Used in web apps, database status codes, API response types, and config-driven applications.

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❓ FAQ – Python Enums

❓ What is an Enum in Python?

✅ A class that defines a set of named constant values, grouped together under a common namespace.

❓ Can I compare an Enum to a string or int?

✅ Only if you’re using StrEnum or IntEnum. Otherwise, compare using .value.

❓ Can I have duplicate values in an Enum?

⚠️ Yes by default, but you can prevent this using @unique.

❓ Can I iterate over enum members?

✅ Yes:

for item in EnumClass:
    print(item.name, item.value)

❓ What’s the difference between Enum, IntEnum, and StrEnum?

Type	Compatible with	Use Case
Enum	enum members only	general-purpose enumerations
IntEnum	integers	comparisons, sorting, numeric ops
StrEnum	strings (Py 3.11+)	APIs, configs, serialization

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