Clean Architecture

This gem provides helper interfaces and classes to assist in the construction of application with Clean Architecture, as described in Robert Martin's seminal book.

Installation

Add this line to your application's Gemfile:

gem 'clean-architecture'

And then execute:

$ bundle install
$ bundle binstubs clean-architecture

Usage

The intention of this gem is to help you build applications that are built from the use case down, and decisions about I/O can be deferred until the last possible moment. It relies heavily on the duckface-interfaces gem to enforce interface implementation.

Use cases as an organisational principle

Uncle Bob suggests that your source code organisation should allow developers to easily find a listing of all use cases your application provides. Here's an example of how this might look in a Rails application.

- lib
  - my_banking_application
    - use_cases
      - retail_customer_opens_bank_account.rb
      - retail_customer_makes_a_deposit.rb
      - ...

Clean architecture principles

• The code that manages your inputs (e.g. a Rails controller) instantiates a persistence layer object
  • Suggest: a class that implements both the Persistence interface and your own persistence interface

  persistence = ActiveRecordPersistence.new

• The code that manages your inputs (e.g. a Rails controller) instantiates a use case actor object
  • Suggest: a class that implements the UseCaseActor interface

  use_case_actor = MyUseCaseActorAdapter.new(devise_current_user)

• The code that manages your inputs (e.g. a Rails controller) instantiates a use case input port object
  • Suggest: a class that implements the BaseParameters interface
  • Suggest: implement the AuthorizationParameters interface if you want to make authorization part of your use case logic
  • Suggest: implement the TargetedParameters if your use case operates on a single object
  • Suggest: use the TargetedParameters entity for an out-of-the-box class that gives you all of these

  input_port = CleanArchitecture::Entities::TargetedParameters.new(
    use_case_actor,
    TargetActiveRecordClass.find(params[:id]),
    strong_params,
    persistence,
    other_settings_hash
  )

• The code that manages your inputs (e.g. a Rails controller) instantiates a use case object
  • Suggest: a class that implements the UseCase interface

  use_case = MyBankingApplication::UseCases::RetailCustomerMakesADeposit.new(input_port)