Breaking the Tech Debt Avoidance Loop: Why Python Developers Get Stuck

• Technical debt compounds like financial debt, becoming more costly over time
• The avoidance loop starts with small decisions that grow into significant problems
• Python-specific patterns make tech debt particularly challenging
• Breaking the loop requires deliberate strategies and cultural shifts

# 1. Type inconsistency debt
def process_item(item):
    # Sometimes item is a dict, sometimes a model object
    # Sometimes returns a string, sometimes returns a list
    if isinstance(item, dict):
        return item.get('name', '')
    else:
        return [item.name]

# 2. Missing docstring debt
def calculate_total(values, apply_discount=False, customer_tier=None):
    # Complex function with no documentation
    # What do parameters mean? What does it return?
    result = sum(values)
    if apply_discount:
        if customer_tier == 'gold':
            result *= 0.9
        elif customer_tier == 'silver':
            result *= 0.95
    return result

# 3. Circular import debt
# In file_a.py
from file_b import ClassB
class ClassA:
    def method(self):
        return ClassB()

# In file_b.py
from file_a import ClassA  # Circular import!
class ClassB:
    def method(self):
        return ClassA()

# 4. Magic string/number debt
def handle_status(status_code):
    if status_code == 1:  # What does 1 mean?
        process_pending()
    elif status_code == 2:  # What does 2 mean?
        process_active()
    # What about other codes?

# 5. Monolithic function debt
def do_everything():
    # 200+ line function that handles authentication,
    # data validation, processing, saving, and notification
    # Impossible to test or maintain
      

Typical SaaS Startup Timeline

• Month 1-6: MVP built quickly with Flask. Small technical shortcuts taken to hit market deadlines.
• Month 7-12: Product gains traction. Team expands from 2 to 6 developers. New features prioritized over refactoring.
• Month 13-18: First major outages occur. New feature development slows as team spends 40% of time on bug fixes.
• Month 19-24: Two senior developers quit, citing "unmaintainable codebase" as a reason. Onboarding new developers takes 3x longer than expected.
• Month 25-30: Company commits to a "quick rewrite" of problematic services, estimated at 3 months.
• Month 31-42: Rewrite continues, now at 10 months. Company loses market position as competitors release new features faster.

Estimated cost: Approximately $1-1.5M in developer salaries spent primarily on rework, plus incalculable opportunity cost of delayed features and lost market position.

# Install key Python tools for tech debt visibility
pip install pylint mypy radon xenon

# Basic code quality check
pylint your_module/

# Type checking with mypy
mypy your_module/

# Code complexity metrics
radon cc your_module/ -a

# Detect functions/classes that are too complex
xenon your_module/ --max-absolute B --max-modules A --max-average A
      

# Before: You need to modify this function
def calculate_price(product_id, quantity):
    prod = Products.get_by_id(product_id)
    if prod != None:
        base = prod.price
        if quantity > 10:
            return base * quantity * 0.9
        else:
            return base * quantity
    return 0

# After: You leave it better than you found it
def calculate_price(product_id: str, quantity: int) -> float:
    """Calculate the final price for a product order.
    
    Args:
        product_id: The unique identifier for the product
        quantity: Number of items being ordered
        
    Returns:
        The final price including bulk discounts
        Returns 0 if product not found
    """
    product = Products.get_by_id(product_id)
    if product is None:
        return 0.0
        
    base_price = product.price
    
    # Apply 10% discount for bulk orders
    discount = 0.9 if quantity > 10 else 1.0
    return base_price * quantity * discount
      

# .pre-commit-config.yaml
repos:
-   repo: https://github.com/pre-commit/pre-commit-hooks
    rev: v4.4.0
    hooks:
    -   id: trailing-whitespace
    -   id: end-of-file-fixer
    -   id: check-yaml
    -   id: check-added-large-files

-   repo: https://github.com/pycqa/isort
    rev: 5.12.0
    hooks:
    -   id: isort
        args: ["--profile", "black"]

-   repo: https://github.com/psf/black
    rev: 23.1.0
    hooks:
    -   id: black
        language_version: python3.10

-   repo: https://github.com/pycqa/flake8
    rev: 6.0.0
    hooks:
    -   id: flake8
        additional_dependencies: [flake8-docstrings]

-   repo: https://github.com/pre-commit/mirrors-mypy
    rev: v1.0.1
    hooks:
    -   id: mypy
        additional_dependencies: [types-requests]
      

# app.py - 4,500 lines of code
from flask import Flask, request, jsonify, render_template
import sqlite3
# 30+ more imports

app = Flask(__name__)

@app.route('/users', methods=['GET'])
def get_users():
    conn = sqlite3.connect('database.db')
    cursor = conn.cursor()
    users = cursor.execute("SELECT * FROM users").fetchall()
    conn.close()
    return jsonify(users)

@app.route('/users', methods=['POST'])
def create_user():
    data = request.json
    # No validation
    conn = sqlite3.connect('database.db')
    cursor = conn.cursor()
    cursor.execute(
        "INSERT INTO users (name, email) VALUES (?, ?)",
        (data['name'], data['email'])
    )
    conn.commit()
    conn.close()
    return jsonify({"status": "success"})

# 50+ more routes defined similarly
      

# app.py - Now just 100 lines
from flask import Flask
from views import register_blueprints
from extensions import db
from config import config_by_name

def create_app(config_name="development"):
    app = Flask(__name__)
    app.config.from_object(config_by_name[config_name])
    
    # Initialize extensions
    db.init_app(app)
    
    # Register blueprints
    register_blueprints(app)
    
    return app

# models/user.py
from extensions import db
from dataclasses import dataclass

@dataclass
class User(db.Model):
    id: int
    name: str
    email: str
    
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(80), nullable=False)
    email = db.Column(db.String(120), unique=True, nullable=False)

# views/user.py
from flask import Blueprint, request, jsonify
from models.user import User
from extensions import db
from schemas.user import UserSchema

user_bp = Blueprint('user', __name__)
user_schema = UserSchema()

@user_bp.route('/users', methods=['GET'])
def get_users():
    users = User.query.all()
    return jsonify(user_schema.dump(users, many=True))

@user_bp.route('/users', methods=['POST'])
def create_user():
    data = user_schema.load(request.json)
    new_user = User(**data)
    db.session.add(new_user)
    db.session.commit()
    return jsonify(user_schema.dump(new_user))
      

1. This week: Run code quality tools on your project and create an inventory of tech debt
2. Next week: Implement automated quality checks in your CI/CD pipeline
3. Next sprint: Schedule 1-2 days for tackling high-priority tech debt items
4. Next month: Create a tech debt roadmap with priorities and estimates
5. Next quarter: Schedule a dedicated refactoring sprint