Can this be done better?

gistfile1.rb

module Frank
  class Sinatra

   def self.inherited(subclass)
      (@@subclasses ||= []) << subclass
      @@subclasses.uniq!
    end

    def self.for_namespace(filter)
      @@subclasses.select{|c| c.to_s.include? filter.to_s }
    end
  end
end