DCI implemented using SimpleDelegator to save method caching

gistfile1.rb

require 'delegate'

class Account < Struct.new(:owner, :amount)
end

class MoneyTransferContext < Struct.new(:source, :destination)
  def transfer(amount)
    # applico i ruoli ai modelli "stupidi"
    source_account = SourceRole.new(source)
    destination_account = DestinationRole.new(destination)

    # definisco le interazioni tra i ruoli
    source_account.draw_money(amount)
    destination_account.deposit(amount)
  end

  class SourceRole < ::SimpleDelegator
    def draw_money(amount)
      self.amount = self.amount - amount
    end
  end

  class DestinationRole < ::SimpleDelegator
    def deposit(amount)
      self.amount = self.amount + amount
    end
  end
end


my_account = Account.new("Stefano", 100.0)
other_account = Account.new("Matteo", 50.0)

MoneyTransferContext.new(my_account, other_account).transfer(10.0)

puts my_account.amount # => 90.0
puts other_account.amount # => 60.0