# File lib/acts_as_indexed/configuration.rb, line 54
    def index_file=(file_path)
      # Under the old syntax this was an array of path parts.
      # If this is still using the array then rewrite to a Pathname.
      if file_path.is_a?(Pathname)
        @index_file = file_path
      else
        @index_file = Pathname.new(file_path.collect{|part| part.to_s}.join(File::SEPARATOR))
      end
    end