Messing with class variables in ruby

class_var_ex.rb

# Execute this file as follows and compare the results in ruby 1.8.*:
#
# ruby class_var_ex.rb
# ruby class_var_ex.rb "include module"
# ruby class_var_ex.rb "include module" "include global"
# ruby "include global"

@@test = 9 if ARGV.last == "include global"

module X
  @@test = 3
  self.instance_variable_set('@test', 4)

  def get_class_variable_from_module
    puts "Class variable from module = " + @@test.to_s
  end

  def get_class_instance_variable_from_module
    puts "Class instance variable from module = " + @test.to_s
  end
end

class A
  extend X

  @@test = 1
  self.instance_variable_set('@test', 2)

  def self.get_class_variable
    puts "Class variable = " + @@test.to_s
  end

  def self.get_class_instance_variable
    puts "Class instance variable = " + @test.to_s
  end
end

class B < A
  B.send(:include, X) if ARGV.first == "include module"

  @@test = 2
  self.instance_variable_set('@test', 1)
end

def extended_modules_class_variable
  puts "Module's class variable = " + X.send(:class_variable_get, '@@test').to_s
end

def extended_modules_class_instance_variable
  puts "Module's class instance variable = " + X.instance_variable_get('@test').to_s
end

puts "Values from A >>>>>>>>>>>>>>"
A.get_class_variable_from_module
A.get_class_instance_variable_from_module
A.get_class_variable
A.get_class_instance_variable

puts "Values from B >>>>>>>>>>>>>>"
B.get_class_variable_from_module
B.get_class_instance_variable_from_module
B.get_class_variable
B.get_class_instance_variable

puts "Values from X >>>>>>>>>>>>>>"
extended_modules_class_variable
extended_modules_class_instance_variable

if ARGV.last == "include global"
  puts "Values from Global scope >>>>>>>>>>>>>>"
  puts "Class variable = " + @@test.to_s
end