Maintaining Consistent Abstractions

Overview

A class interface should present ONE cohesive abstraction. All methods should work toward a consistent purpose at a consistent level.

Core principle: Each class implements one Abstract Data Type (ADT). If you can't identify what ADT the class implements, it has poor abstraction.

Goal: Anyone using the class should see a clear, consistent set of related operations, not a miscellaneous grab-bag.

When to Use

Apply when designing any class:

• New class design
• Reviewing existing classes
• Refactoring
• API design