Memosa is a simple solution for caching method return values in Ruby.

Memosa is designed with the following features in mind:

• Fully compatible with Sorbet.
• Support for memoizing methods on frozen objects.
• Support for preloading and resetting memoized values.
• Support for memoization of class and module methods.
• Support for inheritance of memoized class and instance methods.
• No support for memoization of methods with arguments, which is a feature, not a bug.
• Provides RuboCop rules to ensure consistent usage.
• Provides RBI definitions for Sorbet users.
• Provides RBS definitions for Steep users.

Click here to read the documentation.

Install the gem and add to the application's Gemfile by executing:

bundle add memosa

To memoize a method, simply extend the class with Memosa and use the memoize decorator.

class User
  extend Memosa

  memoize def id
    SecureRandom.uuid
  end
end

user = User.new
user.id # => "ea16e391-20c2-477a-b393-691633a6483f"
user.id # => "ea16e391-20c2-477a-b393-691633a6483f"

Memosa can also memoize class methods:

class Configuration
  class << self
    extend Memosa

    memoize def instance
      new(YAML.load_file("config.yml"))
    end
  end
end

To access the cache directly, include Memosa::API.

class User
  extend Memosa
  include Memosa::API
  # ... etc ...
end

user = User.new
user.memosa # => #<Memosa::Cache>

user.memosa.merge!(id: SecureRandom.id)
user.memosa.delete(:id)
user.memosa.clear

Memosa provides a reset method for resetting the cache, but Memosa::API#clear should be preferred.

user = User.new
user.id # => "ea16e391-20c2-477a-b393-691633a6483f"

Memosa.reset(user)
user.id # => "4690993f-408f-4b7a-824b-c6776782b2fd"

Memosa provides some RuboCop rules to ensure that you're using it correctly.

Add the following configuration to your .rubocop.yml file:

inherit_gem:
  memosa: config/rubocop.yml

If you're using ActiveRecord, you might want to ensure that Memosa caches are flushed whenever the record is reloaded.

class ApplicationRecord < ActiveRecord::Base
  def reload
    super
    Memosa.reset(self)
  end
end

I'm glad you asked. All credit goes to @devinburnette.

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 the created tag, and push the .gem file to rubygems.org.

Bug reports and pull requests are welcome on GitHub at https://github.com/rzane/memosa.