FAQ 4.13 How much effort should be expended to support changethat is, how much is extensibility worth?

FAQ 4.13 How much effort should be expended to support change that is, how much is extensibility worth?

It depends on the specific situation, but don't focus on supporting change to the point that the project won't finish on time.

An extensible product isn't worth much if it has no users. On the other hand, having lots of users but inflexible software means that enhancing and maintaining the software will be an expensive proposition. In today's rapidly changing business climate it can be deadly to have an inflexible software product. It's a delicate balancing act.

Here is a real-life example that illustrates this issue. Two organizations had similar products. One used OO technology to achieve extensibility (a new release every six months); the other shipped a new release every two years. Not only did the rapid-fire organization create four times as many sales opportunities per customer than its slower counterpart, it also used its enhanced features to become the market leader.

The only software that never changes is software that no one uses. Successful software will need to be changed. The hard decision is the judgment call as to the risk/reward ratio for investing in future extensibility. Once this decision has been made, it is important that the developer not undo the decision by gratuitously enhancing the system without authorization. Too many developers add flexibility to the software just because it can be done, paying no attention to whether it should be done.