Checking for AF::Base subclasses without calling .ancestors or creating an enumerator

gistfile1.rb

module ActiveFedora
  class ContentModel
    # Returns an ActiveFedora Model class corresponding to the given uri if one can be found.
    # Returns false if no corresponding model can be found.
    def self.uri_to_model_class( uri )
      verify_base(rc = Model.from_class_uri(uri)) and rc
    end
    def self.verify_base klass
      return false unless klass.is_a? Class
      while (klass = klass.superclass) and klass != ActiveFedora::Base; end
      klass == ActiveFedora::Base
    end
    private_class_method :verify_base
  end
end