mixin-example.rb

module Poco
  def field_id
    @field_id ||= rand
  end
  def field_id=(field_id)
    @field_id = field_id
  end
end

Time.send(:include, Poco)
String.send(:include, Poco)

t = Time.now
puts t.field_id
puts t.is_a?(Time)

s = "chicken"
puts s.field_id
puts s.is_a?(String)