Chapter 7. Complexity

When you work as a professional programmer, chances are you’ll know somebody (or you are somebody!) who’s going through this common development horror story: “We started working on this project five years ago, and the technology we were using/making was modern then, but it’s obsolete now. Things keep getting more and more complex with this obsolete technology, so it keeps getting less and less likely that we’ll ever finish the project. But if we rewrite, we could be here for another five years!”

Another popular one is: “We can’t develop fast enough to keep up with modern user needs.” Or, “While we were developing, Company X wrote a product better than ours much more quickly than we did.”

We know now that the source of these problems is complexity. You start out with a simple project that can be completed in one month. Then you add complexity, and the task will take three months. Then you take each piece of that and make it more complex, and the task will take nine months.

Complexity builds on complexity—it’s not just a linear thing. That is, you can’t make assumptions like: “We have 10 features, so adding 1 more will only add 10 percent more time.” In fact, that one new feature will have to be coordinated with all 10 of your existing features. So, if it takes 10 hours of coding time to implement the feature itself, it may well take another 10 hours of coding time to make the 10 existing features all interact properly with the new feature. The more features there ...

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