1;Meilir Page-Jones, through his consulting company, identified a set of abuses of inheritance. In some cases, these

Question:

1; Meilir Page-Jones, through his consulting company, identified a set of abuses of inheritance. In some cases, these abuses led to lengthy and bloody disputes and gruesome implementations; in one case, it led to the destruction of the development team. In all cases, the error was in not enforcing a generalization (a-kind-of) semantics. In one case, the inheritance hierarchy was inverted: Board-
Member was a superclass of Manager, which was a superclass of Employee. However, in this case, an Employee is not a-kind-of Manager, which is not a-kind-of Board-
Member. In fact, the opposite was true. However, if you think of an Organization Chart, a Board Member is superior to a Manager, which is superior to an Employee. In another example, the client’s firm attempted to use inheritance to model a membership idea (e.g., Student is a member of a club). However, the club should have had an attribute that contained the student members. In the other examples, inheritance was used to implement an association relationship and an aggregation relationship.

Question As an analyst, how can you attempt to avoid these types of inheritance abuses?

2; Using the CRC card in Figure 8-19 and the class diagram in Figure 8-20 as guides, add invariants for the Customer class, the State class, the Product class, and the Product-
Order Association to their respective CRC cards and the class diagram.
Questions 1. How easy is it to interpret the class diagram once all of the invariants were added?
2. Look at the class diagram in Figure 7-15 and the package diagram in Figure 7-22. What would they look like if the invariants were all attached to the diagrams? What would you recommend doing to avoid this situation?

Figure 8-19