反应样板：injectReducerFactory返回关闭？为什么？

Question

在React Boilerplate项目（reducerInjects.js）中，reducerInjectors.js中的injectReducerFactory方法返回一个在jectReducer HOC中执行的闭包。为什么不只在Factory方法中更新商店，而在componentDidMount生命周期方法中执行商店呢？有什么优势？像这样：

export function injectReducerFactory(store, key, reducer) {
    store.injectedReducers[key] = reducer; 
    store.replaceReducer(createReducer(store.injectedReducers));
}

以及在HOC（injectReducer.js）中，类似：

componentWillMount() {
    injectReducer(this.context.store, key, reducer);
}