subclasses_of

# File activesupport/lib/active_support/core_ext/object/extending.rb, line 6
  def subclasses_of(*superclasses) #:nodoc:
    subclasses = []

    # Exclude this class unless it's a subclass of our supers and is defined.
    # We check defined? in case we find a removed class that has yet to be
    # garbage collected. This also fails for anonymous classes -- please
    # submit a patch if you have a workaround.
    ObjectSpace.each_object(Class) do |k|
      if superclasses.any? { |superclass| k < superclass } &&
        (k.name.blank? || eval("defined?(::#{k}) && ::#{k}.object_id == k.object_id"))
        subclasses << k
      end
    end

    subclasses
  end