new Vue过程中，init 函数 的初始化顺序是 initLifecycle(vm) initEvents(vm) initRender(vm) initInjections(vm) // resolve injections before data/props initState(vm) initProvide(vm) // resolve provide after data/propsinitInjections initProvide 函数定义 ：export function initProvide (vm: Component) { const provide = vm.$options.provide if (provide) { vm._provided = typeof provide === 'function' ? provide.call(vm) : provide }}export function initInjections (vm: Component) { const result = resolveInject(vm.$options.inject, vm) if (result) { toggleObserving(false) Object.keys(result).forEach(key => { /* istanbul ignore else */ if (process.env.NODE_ENV !== 'production') { defineReactive(vm, key, result[key], () => { warn( `Avoid mutating an injected value directly since the changes will be ` + `overwritten whenever the provided component re-renders. ` + `injection being mutated: "${key}"`, vm ) }) } else { defineReactive(vm, key, result[key]) } }) toggleObserving(true) }}initInjections 函数的作用是 ：遍历inject的key从父/祖父组件中把provide的值捕捉下来initProvide()就是将当前实例的provide的对象赋值vm._provided这里既然initInjections 是从父/祖父捕捉provide值,为什么不先执行initProvide呢？