A Little Ruby, A Lot of Objects (Brian Marick)
The goal of this book is to teach you a way to think about computation, to show you how far you can take a simple idea: that all computation consists of sending messages to objects. Prerequisites is reader will know at least one programming language, not necessarily.
Author(s): Brian Marick
NA Pages 
This page covers the following topics related to Ruby : Casting type conversions, Arrays, Classes, Hashes, Blocks and procs and lambdas, Inheritance, Control flow, Strings, Symbols, Exceptions, Thread, Methods, Method missing, Numbers, Iteration, Regular Expressions and regex based operations, Comparable, Gem usage, Design patterns and idioms, Loading source files, Range, Comments, Special constants in Ruby, Modules, Ruby version manager, Gem creation / management, Constants, Variable scope and visibility, rbenv, Environment variables, Singletons, File I/O, Time, Queue, Destructuring, IRB, Enumerators, C extensions, Struct, Metaprogramming, Dynamic evaluation, instance eval, Message passing, Keyword arguments, DateTime, Truthiness, JSON with Ruby, Implicit receives, understanding, Monkey patching, Introspection, Monkey patching, Refinements, Monkey patching in Ruby, Catching exceptions with begin rescue, Command line apps, Debugging, Pure RSpec JSON API testing, Recursion, Installation, ERB, Introspection, Random numbers, Getting started with Hanami, OptionParser, Splat operator, Multidimensional Arrays, Enumerable, Ruby access modifiers, Operating system or shell commands, Contributors.
Author(s): programming-books.io
NA Pages
Ruby Programming by Wikibooks.org
This book is currently broken down into several sections and is intended to be read sequentially. Topics covered includes: Notation conventions, Basic Ruby, Ruby Semantic reference, Built in Classes, Standard Library.
Author(s): Wikibooks.org
NA Pages
