Should. you buy Programming Ruby if you already know Ruby?

Also Yes! This book has a detailed reference to Ruby syntax, including the very newest features, and also processes like method lookup and how objects work. There’s a lot of great detail on the Ruby Library. I learned a ton writing this book, you’ll learn a ton reading it.

Ebook: https://pragprog.com/titles/ruby5
Print Book: https://amzn.to/3RX8rfo