Cost Cutter

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Code Standards ​

Conventions for contributing code.

Naming ​

  • Variables/functions: snake_case
  • Classes: PascalCase
  • Constants: ALL_CAPS
  • Files: snake_case.py
  • Private members: _prefixed

Type Hints ​

Required for all functions:

python
def cleanup_volumes(
    session: Session,
    region: str,
    reporter: Reporter,
    dry_run: bool = True
) -> None:
    """Delete volumes."""
    pass

Use modern syntax:

  • list[str] not List[str]
  • dict[str, Any] not Dict[str, Any]
  • str | None not Optional[str]

Docstrings ​

Required for all public functions (Google style):

python
def catalog_volumes(session: Session, region: str, reporter: Reporter) -> list[str]:
    """
    List all EBS volumes in a region.

    Args:
        session: Boto3 session for AWS credentials.
        region: AWS region name.
        reporter: Event reporter instance.

    Returns:
        List of volume IDs.
    """
    pass

Imports ​

Order (enforced by ruff):

  1. Standard library
  2. Third-party (boto3, typer, rich)
  3. Local (from costcutter...)

Error Handling ​

  • Catch specific exceptions: ClientError, ValueError
  • Never use bare except:
  • Log errors: logger.error(...)
  • Report failures: reporter.record(..., status="failed")

Formatting ​

bash
# Auto-format
mise run fmt

# Check linting
mise run lint

Quality Checks ​

Before submitting:

bash
mise run fmt     # Format
mise run lint    # Lint
mise run test    # Test

All must pass.

Next Steps ​