How to Improve Code Quality — 6 Practical Methods

What is code quality?

Code quality is a measure of how maintainable, readable, and reliable code is. High-quality code is easy to understand, easy to change without breaking other things, and behaves correctly under all conditions. Low-quality code is technically "working" but is expensive to maintain and dangerous to modify.

Variable and function names are the first thing reviewers and AI tools evaluate. Good names make bugs visible.

❌ Cryptic names hide intent

def calc(x, y, z):
    r = x * y
    t = r * z
    return t  # What is this calculating?

✅ Names explain the logic

def calculate_order_total(unit_price, quantity, tax_rate):
    subtotal = unit_price * quantity
    total = subtotal * (1 + tax_rate)
    return total  # Crystal clear

Functions longer than 30-50 lines almost always do more than one thing. Split them by responsibility.

❌ 100+ line function doing everything

def process_order(order_data):
    # Validate input
    # Fetch user
    # Check inventory
    # Calculate pricing
    # Apply discounts
    # Charge payment
    # Send email
    # Update database
    # Return response
    pass  # One function, 8 responsibilities = 8 bug vectors

✅ Each function has one job

def process_order(order_data):
    validated = validate_order(order_data)
    user = get_user(validated.user_id)
    items = check_inventory(validated.items)
    price = calculate_price(items, user.discount_tier)
    charge_payment(user.payment_method, price)
    send_confirmation_email(user.email, validated)
    save_order(validated, price)
    return OrderResult(success=True, order_id=validated.id)

Numbers without context are unreadable and unmodifiable. Name them to make code self-documenting.

❌ What do 7 and 0.15 mean?

if days_since_signup < 7:
    discount = price * 0.15

if file_size > 5242880:
    return "File too large"

✅ Named constants explain intent

TRIAL_PERIOD_DAYS = 7
NEW_USER_DISCOUNT_RATE = 0.15
MAX_UPLOAD_SIZE_BYTES = 5 * 1024 * 1024  # 5 MB

if days_since_signup < TRIAL_PERIOD_DAYS:
    discount = price * NEW_USER_DISCOUNT_RATE

if file_size > MAX_UPLOAD_SIZE_BYTES:
    return "File too large"

Commented-out code, unused functions, and unreachable branches confuse readers and suggest the code might be needed again.

❌ Dead code clutters the file

# Old approach — kept just in case
# def legacy_calculate(x):
#     return x * 1.05 + 10

def calculate(x):
    result = x * 1.1
    # TODO: add logging someday
    return result

def never_called_function():  # Dead code
    pass

✅ Delete it — git history has it

def calculate(x):
    return x * 1.1
# If you need the legacy version: git log --all -- legacy_calculate