I believe the key to avoiding code rot lies in sound bottom up design and implementation methodologies (I believe it so strongly that I named my business - Think Bottom Up - after it!). The tools of choice here are:
- Programming by contract
- Layered design
- Focus on decoupling
- Always build with reuse in mind, looking for generic solutions
- Keep frameworks lightweight, simple and focused
As suggested by other respondents, you need to catch problems early. With green developers, this means mentoring (pair programming is great here) and reviews (code and design reviews). With more senior developers, this means vigilance.
Most of all, do not be afraid of refactoring. If refactoring scares you, you're already sunk. If refactoring is seen as "bad", then there is something wrong with your business.
When you fix something, fix it properly. I use the term "fux" to describe a fix that was done the wrong way: it just "fux" your code base.
Cheers,
Dan
