ups.rb

module Ups
  class Configuration
    attr_accessor :user_id,:password,:licence
    def initialzie
      user_id,password,licence=nil,nil,nil
    end
  end
  class << self
    attr_accessor :configuration
  end
  def self.configure
    self.configuration = Configuration.new
    yield(configuration) if block_given?
  end
end

Ups.configure do |config|
  config.user_id = "amar"
  config.password = "password"
  config.licence = "licencenu"
end
Ups.configure.user_id = "amardaxini"
Ups.configuration

ups_singleton.rb

# MOst of time we need single instance of object of configuration
require 'rubygems'
require 'singleton'

module Ups
  class Configuration
    include Singleton
    attr_accessor :user_id,:password,:licence
    def initialzie
      user_id,password,licence=nil,nil,nil
    end
  end
  class << self
    attr_accessor :configuration
  end
  def self.configure
    self.configuration = Configuration.instance
    yield(configuration) if block_given?
  end
end

Ups.configure do |config|
  config.user_id = "amar"
  config.password = "password"
  config.licence = "licencenu"
end
Ups.configure.user_id = "amardaxini"
Ups.configuration