Python Best Practices — Writing Clean Code

Writing clean, maintainable code is a skill. Follow these practices to write professional Python code.

Learning Objectives

• Follow PEP 8 style guidelines
• Write Pythonic idioms
• Structure projects for maintainability
• Handle errors gracefully

PEP 8 Style

# Naming conventions
class UserManager:
    MAX_RETRIES = 3

    def get_user(self):
        user_name = ""

# Line length: 79 characters max
# Imports: one per line, grouped
import os
import sys
from pathlib import Path

# Whitespace
x = 1
y = x + 1
d = {"key": "value"}

Pythonic Idioms

# Use enumerate instead of manual index
for i, item in enumerate(items):
    print(i, item)

# Use zip for parallel iteration
for name, score in zip(names, scores):
    print(f"{name}: {score}")

# Use any/all for boolean checks
if any(x > 10 for x in numbers):
    print("Found large number")

# Use context managers
with open("file.txt") as f:
    data = f.read()

# Use f-strings
message = f"Hello, {name}!"

# EAFP — Easier to Ask Forgiveness than Permission
try:
    value = my_dict["key"]
except KeyError:
    value = default

Project Structure

# my_project/
# ├── src/
# │   └── my_package/
# │       ├── __init__.py
# │       ├── module1.py
# │       └── module2.py
# ├── tests/
# │   ├── __init__.py
# │   ├── test_module1.py
# │   └── test_module2.py
# ├── pyproject.toml
# ├── README.md
# └── .gitignore

Error Handling

# Be specific with exceptions
try:
    result = risky_operation()
except ValueError as e:
    logger.error(f"Value error: {e}")
    raise
except ConnectionError:
    logger.error("Connection failed")
    return fallback_value

# Don't catch all exceptions — be specific

Key Takeaways

1. Follow PEP 8 for consistent style
2. Use Pythonic idioms (enumerate, zip, context managers)
3. Be specific with exception handling
4. Write docstrings for public functions
5. Keep functions small and focused