Agile Class Week 7: Simplicity Is the Key

Have you heard the term "code smell"? If not, don't feel bad because it's a new word for me too. This week, we continued talking about XP (Extreme Programming). I learned how can XP help in recognizing and responding to code smell. According to Martin Fowler, "a code smell is a surface indication that usually corresponds to a deeper problem in the system". In chapter 7 of the book "Learning Agile", some code smells have to do with:

1. How the code is written or designed. a. Very large classes - classes that do many things which can be difficult to understand, instead of separating out into smaller units that are easier to understand. b. Duplicated code - an identical block of code that shows up in more than one place, which can cause bugs especially if a programmer makes a change to three of the duplicates, but forgets to make that change to the fourth. 2. How the units interact with each other. a. Spaghetti code - complex and tangled structure of code. It is impossible to add or change something without breaking other parts of it. b. Lasagna code - code whose layers are so complicated and intertwined that making a change in one layer would necessitate changes in all other layers.

When XP team find something that is complex, they replace it with something simple. Developers fix code smells by constantly refactoring their code, or improving the code structure without changing its behavior. It transforms a mess into clean code and simple design. A simple design always takes less time to finish than a complex one. Performing refactoring step-by-step and running tests after each change are key elements of refactoring that make it predictable and safe. It's always faster and cheaper to replace complex code. By refactoring mercilessly, XP teams avoid technical debt, or code problems that are known but have not been fixed.

Source(s):
Learning Agile: Understanding Scrum, XP, Lean, and Kanban