@attrs.push({attr: attrLabel, val: @settingValue(s)})

    @attrs = _.sortBy(@attrs, 'attr')

  settingValue: (s) ->

    U = (x) => @graph.Uri(x)

    for pred in [U(':value'), U(':scaledValue')]

      try

        return @graph.stringValue(s, pred)

      catch

        null

      try

        return @graph.floatValue(s, pred)

      catch

        null

    throw new Error("no value for #{s}")