Staying in Control

Effective Weapons in the War Against Bugs
MARK PEARCE
Mark is a TMS Associate who has been programming professionally for the past 19 years, working mainly in the investment banking industry. In recent years, Mark has concentrated on the design and development of effective client/server systems. His interest in zero-defect software comes from a previous incarnation as a professional chess player, where one mistake can lose you your next meal. Mark's current ambitions include making more money than he spends, not ever learning any flavor of Java, and finding the perfect mountain running trail.
"At least one statement in this chapter is wrong (but it may be this one)."
Peter Van Der Linden (paraphrased)
Program bugs are highly ecological because program code is a renewable resource. If you fix a bug, another will grow in its place. And if you cut down that bug, yet another will emerge; only this one will be a mutation with long, poisonous tentacles and revenge in its heart, and it will sit there deep in your program, cackling and making elaborate plans for the most terrible time to strike.
Every week seems to bring Visual Basic developers more powerful but also more complex language features, custom controls, APIs, tools, and operating systems. While Visual Basic 5 finally brought us a "grown-up" language with real enterprise pretensions, Visual Basic 6 arrives only a year later, along with a whole new raft of acronyms and concepts. The phrase "technological downpour," coined by a Microsoft executive, strikes a chord with both developers and their managers. In the midst of all this technological chaos, the deadlines become tougher and our tools often refuse to cooperate with one another. If whatever we build lasts at least until we've finished building it, we consider it an unexpected bonus. Yet we are expected to sculpt stable Microsoft Visual Basic code that gives our users more flexible, less costly, and easier-to-use systems.
From this chapter's point of view, the key word is "stable." It's no use being able to churn out ever larger and more capable systems with these new, improved, wash-whiter-than-white tools if all that we succeed in doing is producing more defects. Developers tend to take a casual attitude toward bugs. They know them intimately, including their origin and even their species. A typical programmer looks at bugs in the same manner as an Amazonian tribe member looks at the insect-infested jungle—as an inevitable fact of life. The typical user is more like a tourist from the big city stranded in the same jungle. Surrounded by hordes of disgustingly hairy creepy-crawlies with too many legs and a nasty habit of appearing in the most unexpected places, the user often becomes upset—which is hardly surprising. This different perspective is one that software developers need to consider if they expect to meet user expectations.