Ekene Agunechemba



When you’re coding in Python, sometimes you want a variable that never changes — like the size of a window, or the value of Pi.

Well, bad news first: Python doesn’t have built-in constant protection. That means anyone (including you!) can reassign a value even if it’s meant to be constant.

But don’t worry — there are two common ways to act like you’re using constants.

🧠 Method 1: Naming Convention (The Common Way)

This is what most Python developers use:

WIDTH = 1024
HEIGHT = 768

When other coders see all UPPERCASE names, they know: ⚠️ “Don’t touch this. It’s meant to stay the same.”

But Python won’t stop you from doing this:

WIDTH = 500  # 😱 Whoops! It changed!

So it’s up to you and your team to respect the rule.

🧠 Method 2: Using Enum for Constants

Want to go a little stricter? Use an Enum. Like this:

from enum import Enum

class Constants(Enum):
    WIDTH = 1024
    HEIGHT = 768

Access the values like this:

print(Constants.WIDTH.value)  # ➜ 1024

✅ Now, if someone tries to reassign Constants.WIDTH, Python will complain:

Constants.WIDTH = 500  # ❌ Error!

So Enum gives you some protection — not perfect, but better.

✏️ Practice Time!

Try these 5 questions to lock it in:

  1. What’s the difference between a normal variable and a constant (by naming)?

  2. Rewrite this code using the constant naming convention:

    pi = 3.14159
max_speed = 250
  3. Create a Constants class using Enum that includes MAX_USERS = 100 and API_KEY = 'abc123'.

  4. What happens if you try to do this?

    Constants.WIDTH = 200

    (Explain in one sentence.)

  5. Why do you think Python doesn’t enforce constants the way other languages do?
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