var RadioGroup = Vue.extend({
template: `<RadioGroup v-model="alarmGrade" @on-change="changeAlarmGrade">

          <Radio label="3">
          <span>高</span>
          </Radio>
          <Radio label="2">
          <span>中</span>
          </Radio>
          <Radio label="1">
          <span>低</span>
          </Radio>
          <Radio label="0">
          <span>无</span>
          </Radio>
          </RadioGroup>`,

props: ['row'],
methods: {

changeAlarmGrade (val) {
  this.$emit('test', val)
}

},
data () {

return {
  alarmGrade: ''
}

},
mounted () {

this.alarmGrade = this.row.alarmGrade.toString()

}
})

这个子组件是在父组件中挂载上去的 如何在父组件中取到emit出去的值