34.20. PersistentObject Superclass and Separation of Concerns
A common partial design solution to providing persistence for objects is to create an abstract technical services superclass PersistentObject that all persistence objects inherit from (see Figure 34.17). Such a class usually defines attributes for persistence, such as a unique OID, and methods for saving to a database.
Figure 34.17. Problems with a PersistentObject superclass.
This is not wrong, but it suffers from the weakness of coupling the class to the PersistentObject class—domain classes end up extending a technical services class.
This design does not illustrate a clear separation ...
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