Working Effectively with Legacy Code

Chapter 17: My Application Has No Structure

Long-lived applications tend to sprawl. They might have started out with a well-thought-out architecture, but over the years, under schedule pressure, they can get to the point at which nobody really understands the complete structure. People can work for years on a project and not have any idea where new features are intended to go; they just know the hacks that have been placed in the system recently. When they add new features, they go to the “hack points” because those are the areas that they know best.

There is no easy remedy for this sort of thing, and the urgency of the situation varies widely. In some cases, programmers run up against a wall. It’s difficult to add new features, and that brings ...