dci-ruby

Trygve Reenskaug, the parent of MVC, proposes an evolution to traditional OO paradigm. (www.artima.com/articles/dci_vision.html). This gem makes Data-Context-Interaction paradigm ready to be used in your Ruby application. See also (rubysource.com/dci-the-evolution-of-the-object-oriented-paradigm/).

Installation

Install as usual, either with rubygems

gem install dci-ruby

or including it in your Gemfile and running bundle install:

# Gemfile
gem "dci-ruby"

Use

dci-ruby gives you the class DCI::Context to inherit from to create your own contexts:

class MoneyTransfer < DCI::Context

  # Roles
      role :source_account do
        def transfer(amount)
          player.balance -= amount
        end
      end

      role :target_account do
        def get_transfer(amount)
          player.balance += amount
        end
      end

  # Interactions
      def run(amount=settings(:amount))
        source_account.transfer(amount)
        target_account.get_transfer(amount)
      end
end

Every context defines some roles to be played by external objects (players) and their interactions. This way you have all the agents and operations in a user case wrapped in just one entity instead of spread out throughout the application code.

Use the defined contexts, instantiating them, wherever you need in your code:

MoneyTransfer.new(:source_account => Account.new(1),
                  :target_account => Account.new(2)).run(100)

In a context instance, every role instantiates an object (roleplayer) that gathers the behaviour defined inside its role, and has private access to the original object adopting the role (player): the Account instances above are players. Instances of MoneyTransfer::SourceAccount and MoneyTransfer::TargetAccount accessible inside MoneyTransfer.new via the private instance_methods #source_account and #target_account are roleplayers. Also, every roleplayer has private access to the rest of roleplayers in its context.

Unlike extending players with role modules this Presenter approach gets on well with ruby method call caching mechanism. (see Tony Arcieri’s article DCI in Ruby is completely broken)

When instanciating a Context, the extra no-role pairs given as arguments are read-only attributes accessible inside the instance:

MoneyTransfer.new(:source_account => Account.new(1),
                  :target_account => Account.new(2),
                  :amount => 500).run

here, :amount is not a player (has no associated role) but is still privately accessible in the interactions via settings(:amount).

See the examples folder for examples of use and the DCI-Sample repository for a sample application using DCI through this gem.

dci-ruby

Installation

Use

Copyright