Python Guide

Applies to: Python 3.11+, APIs, CLIs, Data Pipelines, Automation

Core Principles

1. Type Hints Everywhere: All function signatures, class attributes, and module-level variables must have type annotations
2. Explicit Over Implicit: No * imports, no mutable default arguments, no implicit type coercions
3. Virtual Environments Always: Never install into system Python; use venv, uv, or poetry
4. Pytest Over unittest: Use pytest for all testing; fixtures and parametrize over setUp/tearDown
5. PEP 8 + Ruff: Enforce style mechanically; never rely on manual formatting

Guardrails

Python Version