more_complex_getters.rb

class Post < ActiveRecord::Base
 
  has_many :authors
  has_many :post_comments

  attr_accessor :post_authors_cache, :post_comments_cache

  def post_authors
    process_post if post_authors_cache.nil?
    post_authors_cache
  end

  def post_comments
    process_post if post_comments_cache.nil?
    post_comments_cache
  end

  private

  def process_post
    #do some crazy stuff here and set the post_authors_cache
    # some loop where you set two things and only loop through once
    self.post_authors_cache = {}
    self.post_comments_cache = {}
  end

end