Legacy Code

Over the past fifteen years, much has been written about object oriented design and team development processes. The unfortunate thing is that much design and process advice assumes that your project is a blank page. In actuality, greenfield projects are noticably rare. Most projects carry some amount of legacy code. In many new development efforts, the amount of legacy code will overwhelm the amount of new code by factors of 100 to 1, or 1000 to 1. Needless to say, you can't work very fast with a legacy code base. Work is often much slower, but you can speed it up if you establish a strategy to deal with your existing code and mitigate risk as new development goes forward. In this paper, I'll outline a strategy that can be used to work with legacy code. But first let's establish some background.