How do you define a Single Responsibility?

Question

I know about \"class having a single reason to change\". Now, what is that exactly? Are there some smells/signs that could tell that class does not have a single responsibility?

Answer 1

Here are some things that help me figure out if my class is violating SRP:

• Fill out the XML doc comments on a class. If you use words like if, and, but, except, when, etc., your classes probably is doing too much.
• If your class is a domain service, it should have a verb in the name. Many times you have classes like "OrderService", which should probably be broken up into "GetOrderService", "SaveOrderService", "SubmitOrderService", etc.