Add missing comments

lib/sof/node.rb

@@ -1,22 +1,37 @@
 # We transform objects into a tree of nodes
 
 module Sof
-  # abstract base class for nodes in the tree
-  # may be referenced (should be a simple name or number)
+
+  # Before writing the objects are transformed into a tree of nodes.
+  # as the Members (all objects) are a graph (not tree) this is achieved by referencing
+  #
+  # There are only two subclasses, SimpleNode and ObejctNode, for simple or not
+  # The base class only holds the referenced flag
+  # Also nodes must implement the out function
+
   class Node
     include Util
+    # only has one attribute, the referenced flag
+    # This could be anything, but we use a simple number counter which is handled in the Members
+    #   class during construction of the occurrence hash
     def initialize ref
+      #puts "node has ref #{self.class}:#{ref}" if ref
       @referenced = ref
     end
+    attr_reader :referenced
+
     # must be able to output to a stream
+    # This function must be called as super as it handles possible reference marker "& num"
     def out io ,level
       io.write "&#{@referenced} " if @referenced
     end
+
+    # helper function to return the output as a string
+    # ie creates stringio, calls out and returns the string
     def as_string(level)
       io = StringIO.new
       out(io,level)
       io.string
     end
-    attr_reader :referenced
   end
 end