taoidle / python-best-practices

Python Best Practices

Code Style

Type Hints

def process(items: list[str], max_count: int = 10) -> dict[str, int]: ...
def find_user(user_id: int) -> User | None: ...

Error Handling

# Good
try:
    result = process(data)
except ValidationError as e:
    logger.warning(f"Validation failed: {e}")
    return default

Project Structure

src/package_name/
├── __init__.py
├── core/
└── py.typed
tests/
├── conftest.py
└── test_*.py
pyproject.toml

Common Patterns

Anti-Patterns

# Bad: def add(item, items=[]): ...
# Good:
def add(item, items=None):
    items = items or []
    items.append(item)
    return items

Tools