Enduring Legacy Code

Brian Marick blogging over at Exploration Through Example groups approaches to handling legacy code into three classes:

• Rewrite and throw away
• Refactor into submission, ala JoelOnSoftware
• Strangler application, via Martin Fowler

Now if everything was a web application, the issue becomes one of integration and interoperation rather than replacement. e.g. Add a link in the legacy app, and hey it jumps to a shiny new application which provides additional features. Of course, you end up with a heap of systems to manage. However, they cause the least disruption to businesses, and may well turn out to be the least expensive approach in the long run. After all, once shiny code is written, it immediately becomes legacy code.