gistfile1.rb

# Class Tree
# ruby prog.rb > class.dot;dot -Tpng class.dot -o class.png;

def readable(str)
  if str.length >= 30
    return false
  end
  for k in 0..str.length-1
    s = str[k]
    if not ((s>='a' and s<='z') or (s>='A' and s<='Z') or (s >='0' and s<='9'))
      return false
    end
  end
  return true
end

 class ClassTreeNode
   attr_accessor :klass, :subclasses, :objects

   def initialize(klass)
     @klass = klass
     @subclasses = {}
     @objects = []
   end

   def add_class(klass)
     @subclasses[klass] ||= ClassTreeNode.new(klass)
   end

   def add_object(object)
     @objects << object
     self
   end

   def draw(draw_obj = false)
     res = ""
     res += "digraph G {\n  ratio=auto;\n"
     res += draw_it(draw_obj)
     res += "\n}\n"
     return res
   end

   def draw_it(draw_obj = false)
     res = ""
     @subclasses.each do |k, v|
         res += "\"#{k}\" -> \"#{@klass}\";\n"
     end
     
     if draw_obj 
       @objects.each do |k|
         if @klass != "".class and k.to_s != "" and readable(k.to_s)
           res += "\"#{k}\" -> \"#{@klass}\" [color=\"blue\"];\n"
         end
       end
     end

     @subclasses.each do |k, v|
       res += v.draw_it(draw_obj)
     end
     return res
   end

   public :draw, :draw_it
 end

 # Creates or updates a klass_tree.
 # When updating no classes or objects are removed
 def object_browser(classtree = ClassTreeNode.new(Kernel))
   ObjectSpace.each_object do | x |
     classnode = classtree
     x.class.ancestors.reverse[1..-1] \
       .inject(classtree){ | classnode, klass |
       classnode.add_class(klass)
     }.add_object(x)
   end
   classtree
 end

class Demo
end

demo = Demo.new()

class SubDemo < Demo
end

sub = SubDemo.new()

obj  = object_browser()
puts obj.draw(false)