Another memoization gem, this time with simpler, easier to read code that hopefully everyone will feel safe using. It just uses instance variables and hashes, no magic, nothing you wouldn't do in typical @a ||= expensive_op memoization. It just extracts that logic out of methods where it shouldn't be in the first place.

Tested with ruby 2.1.9 and 2.3.1. It most likely works with other versions, it just hasn't been tested with them yet.

Install bundler if you don't already have it (gem install bundler).

Add this line to your application's Gemfile:

gem 'fond_memos'

And then execute:

$ bundle

Or install it yourself as:

$ gem install fond_memos

The class itself is well documented, more info can be found here

To memoize a method, simply require the gem, include the module in your class, and memoize the methods you want. Single and multiple argument methods are handled the same.

require 'fond_memos'

class Widget
  include FondMemos

  def expensive_calculation(a, b)
    # this takes seconds to run! so slow!
  end
  memoize(:expensive_calculation)
end

w = Widget.new
w.expensive_calculation(5, 4)    # slow!
w.expensive_calculation(99, 300) # slow!
w.expensive_calculation(5, 4)    # fast!

If you need to clear a memoized cache (perhaps something else changed an underlying variable which logically invalidated cache), simply call forget.

w.forget(:expensive_calculation)
w.expensive_calculation(5, 4)    # slow again!

After checking out the repo, run bin/setup to install dependencies. Then, run rake test to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

These are battle tested, solid memoization libraries. Check them out to ensure you choose the right library for you!

• memoizable - threadsafe, very elegant design.
• memoist - extracted from the original code from Rails' old ActiveSupport::Memoizable.

Bug reports and pull requests are welcome on GitHub at https://github.com/mclark/fond_memos. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

The gem is available as open source under the terms of the MIT License.