Editing Member variable (section)

=== Ruby ===
<syntaxhighlight lang="ruby">
/*
  Ruby has three member variable types: class, class instance, and instance.
*/

class Dog

  # The class variable is defined within the class body with two at-signs
  # and describes data about all Dogs *and* their derived Dog breeds (if any)
  @@sniffs = true

end

mutt = Dog.new
mutt.class.sniffs #=> true

class Poodle < Dog

  # The "class instance variable" is defined within the class body with a single at-sign
  # and describes data about only the Poodle class. It makes no claim about its parent class
  # or any possible subclass derived from Poodle
  @sheds = false

  # When a new Poodle instance is created, by default it is untrained. The 'trained' variable
  # is local to the initialize method and is used to set the instance variable @trained
  # An instance variable is defined within an instance method and is a member of the Poodle instance
  def initialize(trained = false)
    @trained = trained
  end

  def has_manners?
    @trained
  end

end

p = Poodle.new
p.class.sheds #=> false
p.has_manners? #=> false
</syntaxhighlight>