Advanced

Protocol-Based Resolution

@container.inject
def business_logic(logger: Logger, db: Database) -> str:
    logger.info("Processing")
    return db.query("SELECT 1")

Scopes

• SINGLETON: one instance per container
• TRANSIENT: new instance per resolve
• REQUEST: request-bound lifetime

Testing and Overrides

mock = Mock(spec=Logger)
container.override(logger_token, mock)
...
container.clear_overrides()