Summary
Use cases are a wonderful idea that has been vastly overcomplicated. The real trick to use cases is to _keep them simple_. Remember, tomorrow they are going to change.

Use cases are a wonderful idea that has been vastly overcomplicated. Over and over again I have seen teams sitting and spinning in their attempts to write use cass. Typically they thrash on issues of form rather than substance. They argue and debate over preconditions, postconditions, actors, secondary actors, and a bevy of other things that just don't matter.

The real trick to use cases is to keep them simple. Don't worry about use case forms, just write them on blank paper, or on a blank page in a simple word processor, or on blank index cards. Don't worry about filling in all the details. Details aren't important until much later. Don't worry about capturing all the use cases; that's an impossible task.

The one thing to remember about use cases is: tomorrow they are going to change. No matter how diligently you capture them, no matter how fastidiously you record the details, no matter how thoroughly you think them through, no matter how much effort you apply to exploring and analyzing the requirements, tomorrow they are going to change.

If something is going to change tomorrow, you don't really need to capture its details today. Indeed, you want to postpone the capture of the details until the very last possible moment.

Think of use cases as just in time requirements.

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About the Blogger

Robert C. Martin (Uncle Bob) has been a software professional since 1970 and an international software consultant since 1990. He is founder and president of Object Mentor Inc., a team of experienced consultants who mentor their clients worldwide in the fields of C++, Java, OO, Patterns, UML, Agile Methodologies, and Extreme Programming. In 1995 Robert authored the best-selling book: Designing Object Oriented C++ Applications using the Booch Method, published by Prentice Hall. From 1996 to 1999 he was the editor-in-chief of the C++ Report. In 1997 he was chief editor of the book: Pattern Languages of Program Design 3, published by Addison Wesley. In 1999 he was the editor of "More C++ Gems" published by Cambridge Press. He is co-author, with James Newkirk, of "XP in Practice", Addision Wesley, 2001. In 2002 he wrote the long awaited "Agile Software Development: Principles, Patterns, and Practices", Prentice Hall, 2002. He has published many dozens of articles in various trade journals, and is a regular speaker at international conferences and trade shows.