Fat¶
Fat is an informal qualifier applied to a class, most commonly a controller or a model, that has grown too large in terms of responsibilities, methods, and lines of code.
A fat class violates the Single Responsibility Principle. It is harder to test, understand, and maintain. Common symptoms include: many unrelated methods, large amounts of private helper code, direct database access mixed with business logic, and deep dependencies on infrastructure.
The opposite is a thin class, which delegates most work to collaborators. The right balance depends on architecture: an MVC application typically favours thin controllers and rich domain models or services.
Related terms: fat controller, fat model, god class, big ball of mud.
See also Large Class code smell and Thin controllers, fat models.
Related : Fat Controller, Thin, Slim, Single Responsability Principle (SRP), God Object, Refactoring, Business Logic
