5 Clean Code Principles That Changed How I Write Software

We’ve all been there - staring at code we wrote six months ago, wondering what we were thinking. Over the years, I’ve learned that clean code isn’t about being clever; it’s about being kind to your future self (and your teammates).

Here are five principles that fundamentally changed how I approach software development.

1. Code Should Read Like Prose

Your code is read far more often than it’s written. Make it easy to understand.

Bad:

def calc(x, y, z):
    return (x * y) / z if z != 0 else 0

Good:

def calculate_average_velocity(distance, time, adjustment_factor):
    """Calculate average velocity with adjustment factor applied."""
    if adjustment_factor == 0:
        return 0
    return (distance * time) / adjustment_factor

The second version is self-documenting. No comments needed - the code explains itself.

2. Functions Should Do One Thing (And Do It Well)

A function with a clear, single responsibility is easier to test, debug, and reuse.

Bad:

def process_user(user_data):
    # Validate
    if not user_data.get('email'):
        raise ValueError("Email required")

    # Save to database
    db.save(user_data)

    # Send welcome email
    send_email(user_data['email'], "Welcome!")

    # Log analytics
    analytics.track('user_created', user_data)

Good:

def process_user(user_data):
    validated_user = validate_user_data(user_data)
    saved_user = save_user_to_database(validated_user)
    send_welcome_email(saved_user)
    track_user_creation(saved_user)
    return saved_user

Each function now has a single, clear purpose. Testing and debugging become trivial.

3. Eliminate Magic Numbers and Strings

Future you will thank present you for explaining what those numbers mean.

Bad:

if (user.loginAttempts > 5) {
    lockAccount(user, 1800);
}

Good:

const MAX_LOGIN_ATTEMPTS = 5;
const LOCKOUT_DURATION_SECONDS = 30 * 60; // 30 minutes

if (user.loginAttempts > MAX_LOGIN_ATTEMPTS) {
    lockAccount(user, LOCKOUT_DURATION_SECONDS);
}

Constants make your code self-documenting and easier to modify.

4. Fail Fast and Loudly

Don’t let errors propagate silently. Catch problems early and communicate clearly.

Bad:

def get_user_age(user_id):
    user = db.get_user(user_id)
    if user:
        return user.age
    return None  # Silent failure

Good:

def get_user_age(user_id):
    user = db.get_user(user_id)
    if user is None:
        raise UserNotFoundError(f"User {user_id} not found")
    return user.age

Explicit errors make debugging infinitely easier and prevent bugs from hiding.

5. Delete Code, Don’t Comment It Out

Version control exists for a reason. Commented code creates noise and confusion.

Bad:

function calculatePrice(item) {
    // Old calculation
    // return item.price * 0.9;

    // Previous version
    // return item.price * (1 - item.discount);

    // Current version
    return item.basePrice * item.quantity * (1 - item.discount);
}

Good:

function calculatePrice(item) {
    return item.basePrice * item.quantity * (1 - item.discount);
}

Trust your version control system. If you need old code, git has your back.

The Real Impact

Applying these principles has:

• Reduced debugging time by making code behavior obvious
• Improved team collaboration through readable, maintainable code
• Decreased bug rate by catching errors early
• Accelerated onboarding for new team members

Start Small

You don’t need to refactor everything at once. Start with:

1. Name variables clearly in your next PR
2. Extract one long function into smaller pieces
3. Replace one magic number with a named constant

Small improvements compound over time.

Conclusion

Clean code isn’t about perfection - it’s about clarity and maintainability. These five principles have saved me countless hours of debugging and frustration.

What principles guide your coding? I’d love to hear what works for you.

Further Reading:

• Clean Code by Robert C. Martin
• The Pragmatic Programmer by Hunt and Thomas
• Refactoring by Martin Fowler

What are your favorite clean code practices? Share in the comments below!