Joy of Patterns: Using Patterns for Enterprise Development, The

Maintenance

Most software development work is not done by developing new systems. The majority of work is done in existing systems involving either changing or adding functionality. This form of evolutionary development is often called “maintenance,” although the division between development and maintenance is an arbitrary one. In fact, if you are using an iterative development approach such as that recommended throughout this book, there really is no division. The distinction that does exist, however, is that you have existing internal or external customers. The problem is that modifying existing “working” code often increases its complexity, making it more brittle and much harder to maintain. In addition, most approaches to maintenance violate ...