NetTuts.com kicks off a new series of posts today with this first article covering the SOLID development practices. SOLID is a set of principles that can help make your code more robust and well structured in the long run. In this first post they jump right in with the first letter - "S" for Single Responsibility Principle.

[The Single Responsibility Principle] is one of the five SOLID agile principles. What it states is very simple, however achieving that simplicity can be very tricky. A class should have only one reason to change. But why? Why is it so important to have only one reason for change? [...] Even though you may not use a compiled language, you may need to retest the same class or module for different reasons. This means more QA work, time, and effort.

They go on to talk about how to figure out the "audience" for your class and how that effects what it should contain. A few "class examples" are shared in the post including objects that can print or save themselves. There's a bit of talk about software design ideas to consider and a less obvious example that might be breaking the principle (and how to fix it).