Python Best Practices

Type-First Development

Types define the contract before implementation. Follow this workflow:

1. Define data models - dataclasses, Pydantic models, or TypedDict first
2. Define function signatures - parameter and return type hints
3. Implement to satisfy types - let the type checker guide completeness
4. Validate at boundaries - runtime checks where data enters the system

Make Illegal States Unrepresentable

Use Python's type system to prevent invalid states at type-check time.

Dataclasses for structured data:

from dataclasses import dataclass
from datetime import datetime