Custom Control Structure

custom.rb

# instead of designing a class to return a result object that we
# must interrogate, we could design our class to have a custom
# control structure to make it easy to see the alternatives
# that must be handled
PaymentProcessor.new.charge_money(credit_card,amount).on_success do |transaction_id|
  # happy path
end.on_expired_card do 
  # special message to get them to update their card
end.on_decline do |decline_message|
  # general decline
end.on_exception do |exception|
  # something went wrong and we could try again
end