valuables

Valuables

Sometimes, your objects are only data and no behaviour. These are value objects, and they are defined by their contents. These objects are immutable, so it is safe to let them propagate throughout the system.

Being immutable, value objects cannot be modified; their contents are set once on initialisation. Also, being identified by their contents, two entities with the same contents are considered equal.

Installation

Add this line to your application's Gemfile:

gem 'valuables'

And then execute:

$ bundle

Or install it yourself as:

$ gem install valuables

Usage

class Article
  include Valuables::Entity
  attributes :title, :author, :created_at

  def human_created_at
    super.strftime '%c'
  end
end

article = Article.new(title: 'On Values', author: 'J. Example', created_at: Time.now)
article.title
# => 'On Values'

article = Article.new(title: 'On Values')
# => ArgumentError: missing attributes: author, created_at

article = Article.new(title: 'On Values', author: 'J. Example', created_at: Time.now, tags: ['news'])
# => ArgumentError: unexpected attributes: tags

article1 = Article.new(title: 'On Values', author: 'J. Example', created_at: Time.now)
article2 = Article.new(title: 'On Values', author: 'J. Example', created_at: Time.now)
article1 == article2
# => true

article3 = Article.new(title: 'On Values', author: 'J. Example', created_at: Time.now)
article4 = Article.new(title: 'More Values', author: 'R. Demo', created_at: Time.now)
article3 == article4
# => false

Development

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.

Contributing

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

License

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