gistfile1.rb

class Class

  protected :instance_type

  def initialize(sclass=Object)
    unless sclass.kind_of?(Class)
      raise TypeError, "superclass must be a Class (#{sclass.class} given)"
    end

    set_superclass sclass

    mc = self.metaclass
    mc.set_superclass sclass.metaclass

    super()

    # add class to sclass's subclass list, for ObjectSpace.each_object(Class)
    # NOTE: This is non-standard; Ruby does not normally track subclasses
    sclass.__send__ :add_subclass, self

    sclass.__send__ :inherited, self
  end

  # ...
end