The approach in this book is incredibly important and deserves far wider awareness than it has had so far.

Unfortunately the book itself is less than ideal for working through directly, it would benefit greatly from the polish of professional editing.

However, Gregor Kiczales of University of British Columbia has a absolutely top notch class he teaches based on the book. It's available free on EdX: https://www.edx.org/course/how-code-simple-data-ubcx-htc1x Don't be put off like I was at first by the mass-market title ("How to Code").