Yes, I do realize that writing and editing a book is a large undertaking, and very few (if any) books make it to print with zero errors in them. In fact, many make it to print with code that simply does not work. I have tons of old VB6 and VB.NET code littered with button1, label1, textbox1, and generically named functions; PHP and Python code with foo, bar, a, b, c, x, y, etc. as variables. Most of us probably start out with these bad habits, among others, but eventually we learn that the time saved typing $a instead of $sortParams is lost when we (or someone else) has to actually read and understand our code. When writing a book on the topic of programming, it’s probably a good idea to have an editor who is somewhat familiar with the subject. Leaving something like “Class1” in your sample code does not inspire confidence in the content of your book.