Bulldozer00's Blog

In my travels through the whacky world of software development, I’ve found that bottom up design (a.k.a code first and “discover” the real design later) can lead to lots of unessential complexity getting baked into the code. Once this unessential complexity, in the form of extraneous classes and a rats nest of unneeded dependencies, gets baked into the system and the contraption “appears to work” in a narrow range of scenarios, the baker(s) will tend to irrationally defend the “emergent” design to the death. After all, the alternative would be to suffer humility and perform lots of risky, embarrassing, and ego-busting disentanglement rework. Of course, all of these behaviors and processes are socially unacceptable inside of orgs with macho cultures; where publicly admitting you’re wrong is a career-ending move. And that, my dear, is how we have created all those lovable, “legacy” systems that run the world today.

Don’t get BD00 wrong here. The esteemed one thinks that bottom up design and coding is fine for small scoped systems with around 7 +/- 2 classes (Miller’s number), but this “easy and fun and fast” approach sure doesn’t scale well. Even more ominously, the bottom up coding and emergent design strategy is unacceptable for long-lived, safety-critical systems that will be scrutinized “later on” by external technical inspectors.