A greeting class for understanding basics of ruby.

MegaGreeter.rb

class MegaGreeter
  attr_accessor :names

  # Create the object
  def initialize(names = 'world')
    @names = names
  end

  # say hi to everybody
  def say_hi
    if @names.nil?
      puts '...'
    elsif @names.respond_to?('each')
      # @names is a list of some kind, iterate!
      @names.each do |name|
        puts "Hello #{name}"
      end
    else
      puts "Hello #{@names}"
    end
  end

  def say_bye
    if @names.nil?
      puts '...'
    elsif @names.respond_to?('join')
      # join the list elements with commas
      puts "Goodbye #{@names.join(', ')}. Come back soon:tm:!"
    else
      puts "Goodbye #{@names}. Come back soon:tm:"
    end
  end
end

if __FILE__ == $0
  mg = MegaGreeter.new
  mg.say_hi
  mg.say_bye

  # Change the name to Billy
  mg.names = "Billy"
  mg.say_hi
  mg.say_bye

  # change the name to an array of names
  mg.names = %w[Albert Brenda Charles Dave Engelbert]
  mg.say_hi
  mg.say_bye
  
  # Change to nil
  mg.names = nil 
  mg.say_hi
  mg.say_bye
end