Untangle

This gem provides a very lightweight API to specify dependencies between objects. The key concepts behind it are:

• Make dependencies of your objects visible by declaring them
• Depend on roles, not implementation
• Simplify testing by substituting your dependencies with mocks

Installation

gem install untangle

Define Dependencies

explicit

Explicit definitions contain a direct reference to the actual dependency. The reference can either be a String:

class Person
  extend Untangle

  dependency :translator, 'I18n'
end

or a block:

class Person
  extend Untangle

  dependency(:translator) { I18n }
end

implicit

Implicit definitions have no reference to the actual dependency. The implementation will be inferred from the name. In the following example, the dependency would resolve to Translator.

class Person
  extend Untangle

  dependency :translator
end

Global Dependencies

If you have global dependencies, which are used throughout your app, you can register them globally. This way you can use dependency implicit definitions without a name that corresponds to the implementation.

Untangle.register :translator, 'I18n'

class Blog
  extend Untangle

  dependency :translator
end

You can also use these registered dependencies to inject them into a constructor. This technique does not require that the object under construction knows about explicit_dependencies

Untangle.register :translator, 'I18n'
ExplicitDependencies.register :people_repository, 'PeopleRepository'

class MyPrcoess

  # The argument names must match the registered dependencies
  def initialize(translator, people_repository)
  end

end

Untangle.inject(MyProcess, :new)

Testing