Real-World Software Development

Chapter 4. The Document Management System

The Challenge

After successfully implementing an advanced Bank Statements Analyzer for Mark Erbergzuck you decide to run some errands—including going to an appointment with your dentist. Dr. Avaj has run her practice successfully for many years. Her happy patients retain their white teeth well into old age. The downside of such a successful practice is that every year more and more patient documents get generated. Every time she needs to find a record of prior treatment, her assistants spend longer and longer searching their filing cabinets.

She realizes that it’s time to automate the process of managing these documents and keeping track of them. Luckily, she has a patient who can do that for her! You are going to help by writing software for her that manages these documents and enables her to find the information that will allow her practice to thrive and grow.

The Goal

In this chapter you’ll be learning about a variety of different software development principles. Key to the design of managing documents is an inheritance relationship, which means extending a class or implementing an interface. In order to do this the right way you’ll get to understand the Liskov Substitution Principle, named after famed computer scientist Barbara Liskov.

Your understanding of when to use inheritance will get fleshed out with a discussion of the “Composition over Inheritance” principle.

Finally, you’ll extend your knowledge of how to write automated ...