This paper takes a code’s-eye view of software reuse and evolution. A code-level artifact must be able to attract programmers in order to survive and flourish. The paper addresses the question of what an object might do to encourage programmers to (re-)use it, as opposed to using some other object, or building new ones. THE SELFISH CLASS pattern shows how focusing on code, rather than systems, processes, or personnel, can lead to fresh insights into software evolution and the forces that drive it.

The remaining patterns focus on more specific problems that evolving artifacts might confront. A software artifact that WORKS OUT OF THE BOX provides enough defaults to get the user up and running without needing to know anything about the artifact. An artifact that presents a LOW SURFACE-TO-VOLUME RATIO exposes its services via a relatively compact external interface, while encapsulating significant internal complexity. GENTLE LEARNING CURVE observes that artifacts that don’t pose an undue