Use Case Driven Example for Discussion on Clean Coders

gistfile1.rb

## PayRoll Gem Packages the Application

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

# lib/pay_roll/pay_day_transaction.rb
class PayRoll::PayDayTransaction
  def initialize(date=Date.today)
    @date = date
  end

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

# lib/pay_roll/employee.rb
module PayRoll::Employee
  def pay_date?(date)
    # ...
  end

  def send_pay(pay_check)
    # ...
  end
end

# lib/pay_roll/pay_check.rb
class PayRoll::PayCheck
  # ...
end

## Rails as a delivery service for the PayRoll Application

# config/initializers/pay_roll.rb
PayRoll.config do |config|
  config.database = PayRollDatabase.new
end

# models/pay_roll_database.rb
class PayRollDatabase
  def find_employees
    Employee.active
  end
end

# models/employee.rb
class Employee < ActiveRecord::Base
  include PayRoll::Employee

  scope :active, where(:active => true)
end