shipping.rb in kosher-0.3.0

- old
+ new

@@ -1,15 +1,26 @@
 module Kosher
-  class Shipping < Struct.new(:cents, :currency, :availability)
+  # Shipping details of an offer.
+  #
+  # Shipping costs something (or nothing) and is subject to availability.
+  class Shipping < Structure
+    key :cents, :type => Integer
+    key :currency
+    key :availability, :type => Structure
+
+    # Returns whether the item ships for free.
     def free?
-      cents.to_i == 0
+      cents == 0
     end
 
+    # Returns true if the item is available to ship.
     def kosher?
       availability.kosher?
     end
 
+    # The shipping cost.
     def cost
-      Money.new(cents.to_i, currency)
+      raise TypeError, "Can't render money" unless cents
+      Money.new(cents, currency)
     end
   end
 end