Aggregated.rb

class User < ActiveRecord::Base
  def recent_activities(limit)
    c_stream = comments.order_by(:created_at).to_enum :find_each
    i_stream = items.comments.order_by(:created_at).to_enum :find_each
    b_stream = bids.order_by(:created_at).to_enum :find_each
    ActivityFeedAggregator.new([c_stream, i_stream, b_stream]).next_activities(limit)
  end
end