Configurable - make any object configurable

configurable.rb

require 'ostruct'

module Configurable
  def config
    @config ||= OpenStruct.new
    yield @config if block_given?
  end
  def respond_to?(sym)
    @config.respond_to?(sym) || super(sym)
  end
  def method_missing(sym, *args, &block)
    if @config.respond_to?(sym)
      @config.send(sym, *args, &block)
    else
      super(sym, *args, &block)
    end
  end
end

gistfile1.txt

[tmp] irb -r configurable
>> module Foo
>>   extend Configurable
>>   end
=> Foo
>> Foo.config do |config|
?>     config.setting_a = 'a'
>>     config.setting_b = 'b'
>>   end
=> "b"
>> Foo.setting_a
=> "a"
>> Foo.setting_b
=> "b"