Introduction to Ruby

• What’s Ruby and what are some of its features?

• Much of this course will not focus on many of Ruby’s capabilities and applications (i.e. string manipulation and the Ruby on Rails server-side framework).

  • We will just study a subset of Ruby’s features.

• A Ruby file file_name.rb can be run in Terminal/Command Prompt through the command ruby file_name.rb.

• The Ruby REPL can also be launched through the command irb.

  • To load a Ruby file file_name.rb, you must enter load "file_name.rb".
  • To quit the REPL, you can simply enter quit.

Classes and Objects

• In Ruby,
  1. Everything is a reference to an object.
  2. Objects have functions unique to them known as methods.
  3. Objects interact through method calls (aka messages).
  4. Each object has its own private state.
     1. In Ruby, every object ONLY has a private state. They do not have a public state (unlike objects in other object-oriented programming languages).
  5. Every object is an instance of a class.
  6. A class is a ”blueprint” that dictates an object’s behaviour (e.g. how it handles method calls).
     • It defines the body of objects belonging to it.
     • It also defines the methods that belong to such objects.

Defining Classes