PayRoll application, embedded in Rails, borrowing from Use Case Driven Architecture and DCI

gistfile1.rb

## PayRoll gem

# lib/pay_roll.rb
module PayRoll
  class << self
    attr_accessor :employee_directory
      def config
        yield self
      end
    end
  end
end

# lib/pay_roll/services/pay_day_service.rb
module PayRoll
  class PayDayService
    def initialize(date=Date.today, options={})
      @date = date
 
      options[:employees] ||= PayRoll.employee_directory.active
      @employees = options[:employees].each { |e| e.extend(Payable) }
    end

    def execute
      @employees.each do |e|
        if e.pay_date?(@date)
          pc = PayCheck.new(e.calculate_pay(@date))
          e.send_pay(pc)
        end
      end
    end
  end
end

# lib/pay_roll/roles/payable.rb
module Payable
  def pay_date?(date)
    # ...
  end

  def send_pay(pay_check)
    # ...
  end
end

## Rails application

# app/controllers/pay_day_controller.rb
class PayDayController < ApplicationController
  def create
    PayRoll::PayDayService.new.execute
  end
end

# config/initializers/pay_roll.rb
PayRoll.config do |config|
  employee_directory = EmployeeDirectory.new # alternatively just use Employee model
end

# models/employee_directory.rb
class EmployeeDirectory
  def active
    Employee.active
  end
end

# models/employee.rb
class Employee < ActiveRecord::Base
  scope :active, where(:active => true)
end