Context

context.rb

class TransferringMoney
  include Context

  def self.transfer source_account_id, destination_account_id, amount
    source = Account.find(source_account_id)
    destination = Account.find(destination_account_id)
    TransferringMoney.new(source, destination).transfer amount
  end

  attr_reader :source_account, :destination_account
  def initialize source_account, destination_account
    @source_account = source_account.extend SourceAccount
    @destination_account = destination_account.extend DestinationAccount
  end

  def transfer amount
    in_context do
      source_account.transfer_out amount
    end
  end
  
  ...
end