The Responsible Designer

Successful software systems often live far longer than their original designers anticipated. And over their lifetime, most of those systems evolve. Developers who make modifications, fix bugs, and add new features to long-lived systems have an easier time of it if they keep the code base habitable ("Creating Sustainable Designs," Rebecca Wirfs-Brock, IEEE Software, May/June 2009) and preserve design integrity. But even so, maintenance can be painful when new requirements invalidate initial design assumptions. This paper discussed about methods and techniques on how to achieve software's flexible design. Flexible design is the byproduct of preparation and continued attention to detail. Where there's a lot of variability in a design problem, a flexible solution will incorporate appropriate design hooks that allow for developers to predictably add planned extensions. Once they've established ways to support specific variations, developers can follow predefined extension recipes rather than hacking in new features that are similar to existing ones.