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Why MemoWise?

MemoWise is the wise choice for Ruby memoization, featuring:


Add this line to your application's Gemfile:

gem 'memo_wise'

And then execute:

$ bundle install

Or install it yourself as:

$ gem install memo_wise


When you prepend MemoWise within a class or module, MemoWise exposes three methods:

class Example
  prepend MemoWise
  def slow_value(x)
    sleep x
  memo_wise :slow_value

ex =
ex.slow_value(2) # => 2 # Sleeps for 2 seconds before returning
ex.slow_value(2) # => 2 # Returns immediately because the result is memoized

ex.reset_memo_wise(:slow_value) # Resets all memoized results for slow_value
ex.slow_value(2) # => 2 # Sleeps for 2 seconds before returning
ex.slow_value(2) # => 2 # Returns immediately because the result is memoized
# NOTE: Memoization can also be reset for all methods, or for just one argument.

ex.preset_memo_wise(:slow_value, 3) { 4 } # Store 4 as the result for slow_value(3)
ex.slow_value(3) # => 4 # Returns immediately because the result is memoized
ex.reset_memo_wise # Resets all memoized results for all methods on ex

Methods which take implicit or explicit block arguments cannot be memoized.

For more usage details, see our detailed documentation.


Memoized value retrieval time using Ruby 2.7.2 and benchmark-ips 2.8.3:

Method arguments memo_wise (0.1.0) memery (1.3.0) memoist (0.16.2) memoized (1.0.2) memoizer (1.0.3)
() (none) baseline 11.99x slower 2.53x slower 1.29x slower 3.01x slower
(a, b) baseline 1.94x slower 2.28x slower 1.80x slower 1.96x slower
(a:, b:) baseline 2.20x slower 2.37x slower 2.15x slower 2.18x slower
(a, b:) baseline 1.51x slower 1.68x slower 1.46x slower 1.54x slower
(a, *args) baseline 2.00x slower 2.33x slower 1.96x slower 1.97x slower
(a:, **kwargs) baseline 1.94x slower 2.12x slower 1.87x slower 1.96x slower
(a, *args, b:, **kwargs) baseline 1.92x slower 2.15x slower 1.90x slower 1.91x slower

Benchmarks are run in GitHub Actions and updated in every PR that changes code.

You can run benchmarks yourself with:

$ cd benchmarks
$ bundle install
$ bundle exec ruby benchmarks.rb

If your results differ from what's posted here, let us know!


After checking out the repo, run bin/setup to install dependencies. Then, run rake spec 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


Documentation is Automatically Generated

We maintain API documentation using YARD, which is published automatically at To edit documentation locally and see it rendered in your browser, run:

bundle exec yard server

Documentation Examples are Automatically Tested

We use yard-doctest to test all code examples in our YARD documentation. To run doctest locally:

bundle exec yard doctest

MemoWise's logo was created by Luci Cooke. The logo is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.


Bug reports and pull requests are welcome on GitHub at This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the code of conduct.


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

Code of Conduct

Everyone interacting in the MemoWise project's codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.