RailsCasts Pro episodes are now free!

Learn more or hide this

Memoization

#137 Memoization

Nov 24, 2008 | 5 minutes | Performance, Rails 2.2
Rails 2.2 is out! In this episode I show how to upgrade Rails and then demonstrate one of the new additions: Memoization.
Click to Play Video ▶
  • Download:
  • source codeProject Files in Zip (91.7 KB)
  • mp4Full Size H.264 Video (7.39 MB)
  • m4vSmaller H.264 Video (5.02 MB)
  • webmFull Size VP8 Video (12.2 MB)
  • ogvFull Size Theora Video (9.26 MB)
Browse_code Browse Source Code

There is a newer version of this episode, see the revised episode.

Resources

bash 
sudo gem install rails
sudo gem update --system
sudo gem install rubygems-update
sudo update_rubygems
gem -v
ruby 
class Product < ActiveRecord::Base
  extend ActiveSupport::Memoizable
  
  belongs_to :category
  
  def filesize(num = 1)
    # some expensive operation
    sleep 2
    12345789 * num
  end
  memoize :filesize
end