How to Use Objects: Code and Concepts

Chapter 4. Contracts for Objects

One of the most vital questions in every programmer’s life is: Does this code work? If it turns out that the code does not work properly, you’re in for lengthy debugging sessions, the team will get irritated with their stalled progress, the boss will complain about ever-increasing backlogs, and customers will become frustrated with the reliability of the product. So how can you convince yourself, your team, your boss, and finally your customers that the code you write does work? And more importantly, how can you be confident that it does not just pass your test cases today, but will keep working tomorrow?

The fundamental problem in this area is that it is not obvious what good arguments for “this code works” really ...