classes.rb

#!/usr/bin/env ruby

nodes = []
edges = {}

ObjectSpace.each_object(Class) do |klass|
  # Skip classes outside the global namespace
  next if klass.to_s.include?(':')
  # Skip classes like ARGF.class
  next if klass.to_s.include?('.')
  nodes << klass
  edges[klass] = klass.superclass unless klass.superclass.nil?
end

puts 'digraph classes {'
# Add (or remove) DOT formatting options here
puts '  graph [rotate=0, rankdir="RL", overlap=false, splines=true]'
puts '  node [shape="box", style="filled", color="#333333", fillcolor="#396da4", fontcolor="#ffffff", fontname="Helvetica Neue"]'
puts '  edge [arrowhead="open", color="#666666"]'
nodes.sort_by{|c| c.to_s}.each do |c|
  puts "  #{c}"
end
edges.map.each do |k, v|
  puts "  #{k} -> #{v}"
end
puts '}'