make frame and message indexed

also auto generate a replacement for previous offset class method (dry)

lib/parfait/frame.rb

@@ -19,9 +19,8 @@ module Parfait
   class Frame < Object
     attribute :next_frame
 
-    def self.offset
-      1 + Space.object_space.get_class_by_name(:Frame).object_layout.instance_length
-    end
+    include Indexed
+    self.offset(2)  # 1 == the next_frame attributes above + layout. (indexed_length gets added)
 
   end
 end

lib/parfait/indexed.rb

@@ -139,6 +139,14 @@ module Parfait
       def offset( offset  )
         offset += 1 # for the attribute we add (indexed_length)
 
+        # define methods on the class that includes.
+        # weird syntax, but at least it's possible
+        (class << self;self;end).send :define_method , :get_length_index do
+          offset
+        end
+        (class << self;self;end).send :define_method , :get_indexed do |index|
+          offset + index
+        end
         define_method  :get_offset do
           offset
         end

lib/parfait/message.rb

@@ -9,8 +9,11 @@
 
 module Parfait
   class Message < Object
-    attributes [:next_message , :frame, :caller]
-    attributes [:receiver ,  :return_address , :return_value , :name]
+    attributes [:next_message , :receiver , :frame , :return_address ]
+    attributes [:return_value, :caller , :name ]
+
+    include Indexed
+    self.offset(8)  # 8 == the seven attributes above + layout. (indexed_length gets added)
 
     def initialize next_m
       self.next_message = next_m
@@ -28,9 +31,5 @@ module Parfait
       index = @layout.get_index(name)
       get_at(index)
     end
-
-    def self.offset
-      1 + Space.object_space.get_class_by_name(:Message).object_layout.instance_length
-    end
   end
 end