small rename and new test for layout

lib/parfait/layout.rb

@@ -60,12 +60,18 @@ module Parfait
       names
     end
 
+    alias :list_index :index_of
+    # private inheritance is something to think off, we don't really want the list api exported
+    def index_of name
+      raise "should not rely on layout internal structure, use variable_index"
+    end
+
     # index of a variable name into the layout.
     # layout is a list, so lowest index is 1
     # :layout is a variable for every object, so 1 is taken for :layout
     # still, the index is the same.
     def variable_index name
-      index_of(name)
+      list_index(name)
     end
 
     def sof_reference_name

lib/register/register_reference.rb

@@ -98,7 +98,7 @@ module Register
     real_name = clazz_name.to_s.split('_').last.capitalize.to_sym
     clazz = Parfait::Space.object_space.get_class_by_name(real_name)
     raise "Class name not given #{real_name}" unless clazz
-    index = clazz.object_layout.index_of( instance_name )
+    index = clazz.object_layout.variable_index( instance_name )
     raise "Instance name=#{instance_name} not found on #{real_name}" unless index.is_a?(Numeric)
     return index #  the type word is at index 0, but layout is a list and starts at 1 == layout
   end