react-redux 代码有一段很奇怪的代码

Question

export function wrapMapToPropsFunc(mapToProps, methodName) {
  return function initProxySelector(dispatch, { displayName }) {
    const proxy = function mapToPropsProxy(stateOrDispatch, ownProps) {
      return proxy.dependsOnOwnProps
        ? proxy.mapToProps(stateOrDispatch, ownProps)
        : proxy.mapToProps(stateOrDispatch)
    }

    // allow detectFactoryAndVerify to get ownProps
    proxy.dependsOnOwnProps = true

    proxy.mapToProps = function detectFactoryAndVerify(stateOrDispatch, ownProps) {
      proxy.mapToProps = mapToProps
      proxy.dependsOnOwnProps = getDependsOnOwnProps(mapToProps)
      let props = proxy(stateOrDispatch, ownProps)

      if (typeof props === 'function') {
        proxy.mapToProps = props
        proxy.dependsOnOwnProps = getDependsOnOwnProps(props)
        props = proxy(stateOrDispatch, ownProps)
      }

      if (process.env.NODE_ENV !== 'production') 
        verifyPlainObject(props, displayName, methodName)

      return props
    }

    return proxy
  }
}

其中的

const proxy = function mapToPropsProxy(stateOrDispatch, ownProps) {
      return proxy.dependsOnOwnProps
        ? proxy.mapToProps(stateOrDispatch, ownProps)
        : proxy.mapToProps(stateOrDispatch)
    }

和

proxy.mapToProps = function detectFactoryAndVerify(stateOrDispatch, ownProps) {
    // ...
    let props = proxy(stateOrDispatch, ownProps) 
}

理论上是会死循环才对呀？

有大神出来解释一下吗？

Answer 1

你省略的那个地方是关键

 proxy.mapToProps = mapToProps
 proxy.dependsOnOwnProps = getDependsOnOwnProps(mapToProps)

这里改变了proxy.mapToProps，因此在let props = proxy(stateOrDispatch, ownProps) 中调用的proxy.mapToProps是另外一个函数了