SOURCE

const app = new Vue({
  el:"#app",
  data:{
    firstName:"弗拉基米尔",
    middleName:"伊里奇",
    lastName:"乌里扬诺夫"
  },
  computed:{
    fullName: {
      get:function(){
        return this.firstName + "·" + this.middleName + "·" + this.lastName
      },
      set:function(getStr){
        console.log("在对fullname进行赋值的时候，会自动调用set方法，并可以接收参数:"+getStr)
      }
    }
  }
})

<div id="app">
  <div>{{fullName}}</div>
</div>

#app{color:#fff}