ruby_exception_pattern.rb

# A Pattern for Custom Exception types
module Orders
  class OrdersError < StandardError; end

  class OrdersLineItemError < OrdersError
    def message
      'There was a line item error.'
    end
  end

  class OrdersOtherError < OrdersError
    def message
      'There was another kind of error'
    end
  end

  class OrdersLineItem
    OKAY = true

    def apply
      status = false
      #...
      fail OrdersLineItemError, 'Could put message here too' unless status == OKAY

    rescue OrdersError => e
      puts "#{e} - #{e.message}"
    end
  end
end

order = Orders::OrdersLineItem.new
order.apply # => Could put message here too - There was a line item error.

# Thanks to Panthomakos for the basic pattern: https://gist.github.com/panthomakos/1230673