Acts as Whateverable

client.rb

# app/models/client.rb

class Client < ActiveRecord::Base
  acts_as_whateverable

  # ...
end

whateverable.rb

# lib/whateverable.rb

module Whateverable
  def self.included(base)
    base.send(:extend, ClassMethods)
  end

  module ClassMethods
    def acts_as_whateverable
      class_eval do
        has_many :whatevers, :as => :whateverable, :dependent => :destroy, :order => 'whatevers.created_at ASC'
        accepts_nested_attributes_for :whatevers, :reject_if => :all_blank, :allow_destroy => true
      end
    end
  end
end

class ActiveRecord::Base
  include Whateverable
end