Book Image

Polished Ruby Programming

By : Jeremy Evans
Book Image

Polished Ruby Programming

By: Jeremy Evans

Overview of this book

Anyone striving to become an expert Ruby programmer needs to be able to write maintainable applications. Polished Ruby Programming will help you get better at designing scalable and robust Ruby programs, so that no matter how big the codebase grows, maintaining it will be a breeze. This book takes you on a journey through implementation approaches for many common programming situations, the trade-offs inherent in each approach, and why you may choose to use different approaches in different situations. You'll start by refreshing Ruby fundamentals, such as correctly using core classes, class and method design, variable usage, error handling, and code formatting. Then you'll move on to higher-level programming principles, such as library design, use of metaprogramming and domain-specific languages, and refactoring. Finally, you'll learn principles specific to web application development, such as how to choose a database and web framework, and how to use advanced security features. By the end of this Ruby programming book, you’ll be a well rounded web developer with a deep understanding of Ruby. While most code examples and principles discussed in the book apply to all Ruby versions, some examples and principles are specific to Ruby 3.0, the latest release at the time of publication.
Table of Contents (23 chapters)
1
Section 1: Fundamental Ruby Programming Principles
8
Section 2: Ruby Library Programming Principles
17
Section 3: Ruby Web Programming Principles

Replacing class variables

There are a few features in Ruby you should never use, and class variables are one of them. Class variable semantics are bad enough that the Ruby core team now recommends against their use, and no longer considers it worth it to even fix bugs in how class variables are handled. This is a shame because class variables almost have behavior you want. However, class variable behavior is just different enough from what you want to not be useful.

At first appearance, class variables have desirable qualities:

  • You can access them in the class itself.
  • You can access them when reopening the singleton class in the class itself.
  • You can access them in the class's methods.
  • You can access them in all of these places in any of the class's subclasses.

Here's an example:

class A
  @@a = 1
  class << self
    @@a
  end
  def b
    @@a
 ...