for settingStr in Array.from(toClear)

      @activeSettings.deleteSetting(U(settingStr))

  clearSettings: ->

    @activeSettings.clear()

  register: (device, deviceAttr, graphValueChanged) ->

    @activeSettings.registerWidget(device, deviceAttr, graphValueChanged)

  shouldBeStored: (deviceAttr, value) ->

    # this is a bug for zoom=0, since collector will default it to

    # stick at the last setting if we don't explicitly send the

    # 0. rx/ry similar though not the exact same deal because of

    # their remap.

    return value? and value != 0 and value != '#000000'

  emptyEffect: ->

    @activeSettings.forAll(@_removeEffectSetting.bind(@))

  controlChanged: (device, deviceAttr, value) ->

    # value is float or #color or (Uri or null)

    if (value == undefined or (typeof value == "number" and isNaN(value)) or (typeof value == "object" and value != null and not value.id))

      throw new Error("controlChanged sent bad value " + value)

    effectSetting = @activeSettings.effectSettingLookup(device, deviceAttr)

    if @shouldBeStored(deviceAttr, value)

      if not effectSetting?

        @_addEffectSetting(device, deviceAttr, value)

      else

        @_patchExistingEffectSetting(effectSetting, deviceAttr, value)

    else

      @_removeEffectSetting(effectSetting)

  _nodeForValue: (value) ->

    if value.id?

      return value

    return @graph.prettyLiteral(value)

  _addEffectSetting: (device, deviceAttr, value) ->

    log('change: _addEffectSetting', deviceAttr.value, value)

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

    quad = (s, p, o) => @graph.Quad(s, p, o, @ctx)

    effectSetting = @graph.nextNumberedResource(@effect.value + '_set')

    @activeSettings.addSettingsRow(device, deviceAttr, effectSetting, value)

    addQuads = [

      quad(@effect, U(':setting'), effectSetting),

      quad(effectSetting, U(':device'),  device),

      quad(effectSetting, U(':deviceAttr'), deviceAttr),

      quad(effectSetting, valuePred(@graph, deviceAttr), @_nodeForValue(value))