vue 可写的computed

 computed可以接受一个get、set函数的对象，变成可写的computed（创建一个可写的 ref 对象）。

<script setup lang="ts">
import { ref, computed } from "vue"

const count = ref(1)

// const plusOne = computed(() => count.value + 1) 只读的计算属性ref

const plusOne = computed({   // 可写的计算属性 ref
  get:() => count.value + 1,
  set:(val) =>{
    count.value = val - 1
  }
})

/**
 * Make the `plusOne` writable.
 * So that we can get the result `plusOne` to be 3, and `count` to be 2.
*/

plusOne.value++

</script>

<template>
  <div>
    <p>{{ count }}</p>
    <p>{{ plusOne }}</p>
  </div>
</template>