"order" example refined

examples/order.rb

@@ -13,7 +13,11 @@ class Order
   text_node :reference, "@reference"
   object_node :client, Client, "Client"
   hash_node :items, Item, "Item", "@reference"
-  array_node :signatures, Signature, "Signatures", "Signed-By"
+  array_node :signatures, Signature, "Signatures", "Signed-By", :optional=>true, :default_value=>[]
+
+  def total_price
+    items.values.map{|i| i.total_price}.inject(0){|x,y|x+y}
+  end
 end
 
 
@@ -52,5 +56,5 @@ class Signature
   include XML::Mapping
 
   text_node :name, "Name"
-  text_node :position, "Position"
+  text_node :position, "Position", :optional=>true, :default_value=>"Some Employee"
 end

examples/order.xml

@@ -42,7 +42,6 @@
 
     <Signed-By>
       <Name>Miles O'Brien</Name>
-      <Position>packer</Position>
     </Signed-By>
   </Signatures>
 

examples/order_usage.intin.rb

@@ -2,10 +2,58 @@
 $:.unshift "../lib"
 require 'order' #<=
 #:visible:
+####read access
 o=Order.load_from_file("order.xml") #<=
 o.reference #<=
 o.client #<=
-o.signatures #<=
 o.items.keys #<=
 o.items["RF-0034"].descr #<=
 o.items["RF-0034"].total_price #<=
+o.signatures #<=
+o.signatures[2].name #<=
+o.signatures[2].position #<=
+## default value was set
+
+o.total_price #<=
+
+####write access
+o.client.name="James T. Kirk"
+o.items['RF-4711'] = Item.new
+o.items['RF-4711'].descr = 'power transfer grid'
+o.items['RF-4711'].quantity = 2
+o.items['RF-4711'].unit_price = 29.95
+
+s=Signature.new
+s.name='Harry Smith'
+s.position='general manager'
+o.signatures << s
+xml=o.save_to_xml #convert to REXML node; there's also o.save_to_file(name) #<=
+xml.write($stdout,2) #<=
+
+####Starting a new order from scratch
+o = Order.new #<=
+## attributes with default values (here: signatures) are set
+## automatically
+
+#:handle_exceptions:
+xml=o.save_to_xml #<=
+#:no_exceptions:
+## can't save as long as there are still unset attributes without
+## default values
+
+o.reference = "FOOBAR-1234"
+
+o.client = Client.new
+o.client.name = 'Ford Prefect'
+o.client.address = Address.new
+o.client.address.street = 'Park Av. 42'
+o.client.address.city = 'small planet'
+o.client.address.zip = 17263
+o.client.address.state = 'Betelgeuse system'
+
+o.items={'XY-42' => Item.new}
+o.items['XY-42'].descr = 'improbability drive'
+o.items['XY-42'].quantity = 3
+o.items['XY-42'].unit_price = 299.95
+
+o.save_to_xml.write($stdout,2) #<=