Inheritance Hierarchies Without Polymorphic Assignments

Inheritance hierarchies without their respective polymorphic assignments point to the presence of unnecessary generalizations. If no polymorphic assignments exist, this flexibility will not be used, and inheritance can be replaced by uses relations.

Reference

M. Lippert, S. Roock, “Refactoring in Large Software Projects: Performing Complex Restructurings Successfully”. John Wiley and Sons, 2006.