Object Design Style Guide

Chapter 9. Changing the behavior of services

This chapter covers

• Changing behavior without changing code
• Making behaviors configurable and replaceable
• Introducing abstractions to allow for composition and decoration
• Avoiding inheritance for overriding object behaviors
• Making classes final and methods private to prevent object abuse

You can design your services to be created and used in certain ways. But the nature of a software project is that it will change over time. You’ll often modify a class in such a way that, when it’s used, it will behave the way you want it to. However, modifying a class comes with a cost: the danger of breaking it in some way. A common alternative to changing a class is to override some of its methods, but this can ...