Navigating C++ and Object-Oriented Design

14.8. Putting It All Together

Implementing Persistence with Multiple Inheritance

Chapter 7 defines a String class that makes it easy to work with character strings as objects (Listing 7.2 on page 312). Chapter 11 introduces a Shape abstract base class that defines behaviors for a hierarchy of Circle, Square, and RTriangle objects (Listing 11.23 on page 531). Neither the String class nor the Shape hierarchy is persistent, but a technique to design persistence objects is presented in Chapter 12 with a Solid class hierarchy (see “Persistence” on page 586).

Suppose existing classes (like String and Shape) need to be persistent. What design approach should we take? We'd like our objects to be persistent with newer applications, but the old code still ...