Brian Foote on Prototyping

Big Ball of Mud is a collection of patterns by Brian Foote, published in 1999. The title stems from one of the patterns, Big Ball of Mud, the "most frequently deployed of software architectures". Though this might sound like a joke at first the article contains a lot of really useful information on the forces at work when dealing with large codebases and legacy code. I especially like his take on prototyping applications.

Did you ever find yourself in the following situation? A customer agrees to build a prototype of an application to learn and to see something in action. After the prototype is finished the customer tries to force you to reuse the prototype, "because it already does what we need". Cold sweat, you probably were taking lots of shortcuts in the prototype and didn't build it with maintainability in mind. This is what Brian recommends to circumvent this situation:

One way to minimize the risk of a prototype being put into production is to write the prototype in using a language or tool that you couldn't possibly use for a production version of your product.

Three observations:

1. Nowadays the choice of languages doesn't matter that much for running the code in production with virtual machines that support a lot of languages.
2. This only holds true for prototypes that are used to explore the domain. When doing a technical proof of concept at least some parts of the prototype need to use the intended technology.
3. Prototypes are sometimes also used to make the team familiar with a new technology that is set for the project.

Nevertheless this is a really useful advice to keep in mind.