Using RoleOf relationship in design pattern instantiation

The scattering of pattern logic (the attributes and methods of pattern role) is the most typical problem on design pattern instantiation, that is, pattern logic scatters across multiple business classes, which causes problems, such as, debasing the reusability of pattern logic, losing the instantiation information of pattern (traceability and overlapping problem) etc. To resolve these problems in design level, an approach to design pattern instantiation based on RoleOf relationship is proposed. It treats role as the independent modeling element and introduces RoleOf relationship between business class and role, which makes the business logic and the pattern logic completely separated, thus improves its reusability. Through the extension of UML, the meta-model and semantics of RoleOf relationship, and stereotypes and tagged values used for identify pattern information are provided, it resolves the traceability and overlapping problem. Finally, the implementation method of RoleOf relationship is discussed through an example.