Your Python Class Is a God Object (Here’s How to Fix It)

A walkthrough of refactoring a Python 'god object' — a class that accumulates too many responsibilities over time. Using a machine learning churn experiment as the example, the refactor extracts a frozen dataclass for configuration with built-in validation via __post_init__, converts workflow steps (data loading, cleaning, feature engineering, model training) into standalone functions, and keeps only data-related behavior inside the class. The key rule of thumb: put behavior in a class only if it validates, derives from, or is tightly coupled to the class's own data; move everything else out into functions.