# add method to String class
class String
  # add method :underscore for String class to convert Class name in camelcase
  def underscore
    word = dup
    word.gsub!(/::/, '/')
    word.gsub!(/([A-Z]+)([A-Z][a-z])/, '\1_\2')
    word.gsub!(/([a-z\d])([A-Z])/, '\1_\2')
    word.tr!('-', '_')
    word.downcase!
    word
  end
end