<?php
namespace?app\index\controller;

use?think\Controller;
use?think\Request;

class?Index?extends?Controller
{
????public?function?__construct(){
????????config('before',?'beforeAction');
????}
????public?function?index(Request?$request)
????{
????????return?$this->fetch();
????}
}

上面的代碼，直接跑會報一個‘

Call to a member function fetch() on a non-object

’的錯誤，但是刪除掉construct函數(shù)后就沒問題了，請問這個是怎么沒一個情況？