def route_from(oth)
      # you can modify `rel', but can not `oth'.
      begin
        oth, rel = route_from0(oth)
      rescue
        raise $!.class, $!.message
      end
      if oth == rel
        return rel
      end

      rel.set_path(route_from_path(oth.path, self.path))
      if rel.path == './' && self.query
        # "./?foo" -> "?foo"
        rel.set_path('')
      end

      return rel
    end
def route_from(oth)
      # you can modify `rel', but can not `oth'.
      begin
        oth, rel = route_from0(oth)
      rescue
        raise $!.class, $!.message
      end
      if oth == rel
        return rel
      end

      rel.set_path(route_from_path(oth.path, self.path))
      if rel.path == './' && self.query
        # "./?foo" -> "?foo"
        rel.set_path('')
      end

      return rel
    end
== Args

 +oth+::
    URI or String

 == Description

 Calculates relative path from oth to self

 == Usage

   require 'uri'

   uri = URI.parse('http://my.example.com/main.rbx?page=1')
   p uri.route_from('http://my.example.com')
   #=> #<URI::Generic:0x20218858 URL:/main.rbx?page=1>