metaprogramming1.rb

class A
def initialize
 @a = 11
 @@a = 22

end
 @a = 1
 @@a = 2

end

puts A.instance_variable_get(:@a)
puts A.class_variable_get(:@@a)
a = A.new
puts a.instance_variable_get(:@a)
puts A.class_variable_get(:@@a)

metaprogramming2.rb

class I
 def like arg
 puts "%s %s %s" % [self.class, self.class.instance_methods(false), arg]
 end
end

c, m, arg = gets.split # input 'I like metaprogramming.'

i = I.new
i.like(arg)

metaprogramming3.rb

var = class A

  @@a = 1

  @a = 2

  a = 3
# Write your code here. Use binding method.
binding

end

puts eval('[@@a, @a, a]', var).inspect  # Replace '*****' to your code

metaprogramming4.rb

String.class_eval do
  def tr_vowel
    tr 'aeiou', '*'
  end
  def self.tr_vowel str
    str.tr 'aeiou', '*'
  end
end

puts "hello".tr_vowel 
puts String.tr_vowel "hello"