Thursday, September 29, 2011

Beware Duplicated Code

Test code has a self-esteem problem: it thinks it’s there as a one-off, to be thrown away. It exercises the product once, and that’s good enough to check the code in. Sometimes, hardly any thought goes into test code quality.

For games about sliding letters around on a touch screen, this makes some sense in that quality issues are low-impact anyway. But personally, that’s not why I like IT: I want to help computers solve important, impactful problems for people. Doing quality well becomes a real challenge.

Everybody knows about object-oriented (OO) principles, but when documentation is weak and pressures of productivity are high, code gets copied around and common problems get re-implemented. When this happens, cost and risk go up: bugs and oracle changes have to be addressed in more than one place. Sometimes code even gets abandoned, so it might look like a work item but it’s really not.

Find a way to use OO principles to minimize code duplication and keep the code relevant, just as with product code.

Either code is part of the product quality, or it’s not. If code isn’t used, get rid of it (it can be recovered; that’s what source code control is for) or comment any unusual status of the code for the product (e.g. class/method/member isn’t used right now, but kept around for some specific feature/milestone). Stray code can be expensive, because it can create maintenance cost. Commented-out code should be unusual, and if it’s needed, the commenting-out needs to be commented as to why it’s needed.

If it’s not contributing, get it off the team J

Duplicated code can easily become nearly-duplicated code, which rapidly creates a lot of cost and risk. True, you’re not shipping it, but keeping it readable and maintainable is very important. See my last post on the importance of this.

Do you have any fun (fun, in retrospect) bad-code stories?

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