diff --git a/lib/sof/all.rb b/lib/sof/all.rb
index 873ea2c3..49ce053e 100644
--- a/lib/sof/all.rb
+++ b/lib/sof/all.rb
@@ -1,4 +1,5 @@
 require_relative "members"
+require_relative "writer"
 require_relative "array"
 require_relative "occurence"
 
diff --git a/lib/sof/array.rb b/lib/sof/array.rb
index 4ea037cc..02b2177e 100644
--- a/lib/sof/array.rb
+++ b/lib/sof/array.rb
@@ -1,9 +1,4 @@
 Array.class_eval do
-  def add_sof(members , level)
-    each do |o|
-      members.add(o , level + 1)
-    end
-  end
   def to_sof(io , members)
     each do |object|
       io.write("\n")
diff --git a/lib/sof/known.rb b/lib/sof/known.rb
new file mode 100644
index 00000000..216296b0
--- /dev/null
+++ b/lib/sof/known.rb
@@ -0,0 +1,13 @@
+module Sof
+  class Known
+    @@mapping = {
+      MethodDefinition =>  [:name , :args , :receiver , :return_type , :blocks]
+    }
+    def self.is clazz
+      @@mapping.has_key? clazz
+    end
+    def self.attributes clazz
+      @@mapping[clazz]
+    end
+  end
+end
diff --git a/lib/sof/members.rb b/lib/sof/members.rb
index cd0ba3ee..5ef8098d 100644
--- a/lib/sof/members.rb
+++ b/lib/sof/members.rb
@@ -7,29 +7,31 @@ module Sof
       @objects = {}
       add(root ,0 )
     end
-    attr_reader :objects
+    attr_reader :objects , :root
     
     def add object , level
+      return if Members.is_value?(object)
       if( @objects.has_key?(object) )
         occurence = @objects[object]
         occurence.level = level if occurence.level > level
-      else
-        o = Occurence.new( object , @counter , level )
-        @objects[object] = o
-        c = @counter
-        @counter = @counter + 1
-        if( object.respond_to?(:attributes))
-          object.attributes.each do |a|
-            val = object.send a
-            add(val , level + 1)
-          end
-        elsif not value?(object)
-          object.add_sof(self , level)
+        return
+      end
+      o = Occurence.new( object , @counter , level )
+      @objects[object] = o
+      @counter = @counter + 1
+      attributes = attributes_for(object)
+      attributes.each do |a|
+        val = object.instance_variable_get "@#{a}".to_sym
+        add(val , level + 1)
+      end
+      if( object.is_a? Array )
+        object.each do |a|
+          add(a , level + 1)
         end
       end
     end
 
-    def value? o
+    def self.is_value? o
       return true if o == true
       return true if o == false
       return true if o == nil
@@ -38,38 +40,13 @@ module Sof
       return true if o.class == String
       return false
     end
-    def write
-      io = StringIO.new
-      output io , @root
-      io.string
-    end
 
-    def output io , object
-      occurence = @objects[object]
-      raise "no object #{object}" unless occurence
-      indent = " " * occurence.level
-      io.write indent
-      if(object.respond_to? :to_sof)
-        object.to_sof(io , self)
+    def attributes_for object
+      if( Known.is( object.class ))
+        Known.attributes(object.class)
       else
-        io.write object.class.name
-        if( object.respond_to?(:attributes))
-          object.attributes.each do |a|
-            val = object.send a
-            io.write( a )
-            io.write( " " )
-            output( io , val)
-          end
-          io.puts ""
-        else 
-          raise "General object not supported (yet), need attribute method #{object}"
-        end
+        object.instance_variables.collect{|i| i.to_s[1..-1].to_sym } # chop of @
       end
     end
-
-    def self.write object
-      members = Members.new object
-      members.write
-    end
   end
 end
diff --git a/lib/sof/writer.rb b/lib/sof/writer.rb
new file mode 100644
index 00000000..fc29c911
--- /dev/null
+++ b/lib/sof/writer.rb
@@ -0,0 +1,46 @@
+module Sof
+  class Writer
+    def initialize members
+      @members = members
+    end
+
+    def write
+      io = StringIO.new
+      output io , @members.root
+      io.string
+    end
+
+    def output io , object
+      if Members.is_value?(object)
+        object.to_sof(io , self)
+        return
+      end
+      occurence = @members.objects[object]
+      raise "no object #{object}" unless occurence
+      indent = " " * occurence.level
+      io.write indent
+      if(object.respond_to? :to_sof)
+        object.to_sof(io , self)
+      else
+        io.write object.class.name
+        if( object.respond_to?(:attributes))
+          object.attributes.each do |a|
+            val = object.send a
+            io.write( a )
+            io.write( " " )
+            output( io , val)
+          end
+          io.puts ""
+        else 
+          raise "General object not supported (yet), need attribute method #{object}"
+        end
+      end
+    end
+
+    def self.write object
+      writer = Writer.new(Members.new(object) )
+      writer.write
+    end
+    
+  end
+end
diff --git a/lib/virtual/method_definition.rb b/lib/virtual/method_definition.rb
index 9ebc5ff3..2340e16d 100644
--- a/lib/virtual/method_definition.rb
+++ b/lib/virtual/method_definition.rb
@@ -34,9 +34,6 @@ module Virtual
     def MethodDefinition.main
       MethodDefinition.new(:main , [] , Virtual::SelfReference )
     end
-    def attributes
-      [:name , :args , :receiver , :return_type , :blocks]
-    end
     def initialize name , args , receiver = Virtual::SelfReference.new , return_type = Virtual::Mystery , start = MethodEnter.new()
       @name = name.to_sym
       @args = args
diff --git a/test/sof.rb b/test/sof.rb
index 3b12cf44..0ff33fdd 100644
--- a/test/sof.rb
+++ b/test/sof.rb
@@ -6,12 +6,12 @@ end
 class BasicSof < MiniTest::Test
 
   def test_true
-    out = Sof::Members.write(true)
-    assert_equal  " true\n" , out
+    out = Sof::Writer.write(true)
+    assert_equal  "true" , out
   end
   def test_num
-    out = Sof::Members.write(124)
-    assert_equal  " 124\n" , out
+    out = Sof::Writer.write(124)
+    assert_equal  "124" , out
   end
 
 end
\ No newline at end of file