file.coffee

App.RadioButtonGroup = Em.View.extend
  templateName: 'radio_button_group'
  classNames: ['radio-group']
  groupName: (->
    "radiogroup-#{Em.guidFor(@)}"
  ).property()

  change: ->
    @set 'value', @$('input:checked').val()

  updateSelected: (->
    @$("input[value=#{@get('value')}]")[0].checked = true
  ).observes 'value'

  didInsertElement: -> @updateSelected()