Vue3 setup 的作用实例详解

<script>
import { onMounted, toRefs } from "vue";
export default {
  props: {
    msg: "abc",
  },
  setup(props, context) {
    let { msg } = toRefs(props);
    let { attrs, slots, emit } = context;
    console.log(props, context);
    let num = 10;
    return {
      num,
    };
    // 和setup，嵌套的生命周期
    // onMounted(() => {
    //   console.log("onMounted", num);
    // });
  },
  // 和setup，并列的生命周期
  mounted() {
    console.log("挂载后");
    console.log(this.$options);
  },
  data() {
    return {};
  },
  methods: {},
};
</script>

export function setupComponent(instance){
    let { type,props,children}  = instance.vnode
    let {data,render,setup} = type
    //初始化属性
    initProps(instance,props);
    instance.proxy = new Proxy(instance,instanceProxy);
    if(data){
        if(!isFunction(data)){
            return console.warn('The data option must be a function.')
        }
        //给实例赋予data属性
        instance.data = reactive(data.call({}))
    }
    if(setup){
      //setup的第二个参数，包含emit,attrs，slots等
      const context = {}
      const setupResult = setup(instance.props,context)
      if(isFunction(setupResult)){
        instance.render = setupResult
      }else if(isObject(setupResult)){
        instance.setupState = proxyRefs(setupResult)
      }
    }
    if(!instance.render){
      if(render){
      instance.render = render

      }else {
        //模板编译
      }
    } 
}

const instanceProxy = {
    get(target,key){
        const { data,props,setupState} = target
        if(data && hasOwn(data,key)){
            return data[key]
        }else if(setupState && hasOwn(setupState,key)){
          return setupState[key]
        }
        else if(props && hasOwn(props,key)){
            return props[key]
        }
        let getter = publicProperties[key]
        if(getter){
            return getter(target)
        }
    },
    set(target,key,value,receiver){
        // debugger
        const {data,props,setupState} = target
        if(data && hasOwn(data,key)){
            data[key] = value
        }else if( setupState && hasOwn(setupState,key)){
            setupState[key]  = value
        }
        else if(props && hasOwn(props,key)){
            console.warn('props not update');
            return false
        }
        return true
    }
}