关于 view 无法调用自定义函数的问题

根据文章(L02 Laravel 教程)的步骤操作，但是最后出现找不到函数问题：

Facade\Ignition\Exceptions\ViewException

Call to undefined function route_class() (View: /home/vagrant/code/laraBBS/resources/views/layouts/app.blade.php)

1. 添加app\helpers.php

   function route_class()
   {
   return str_replace('.', '-', Route::currentRouteName());
   }

2. 添加自动加载项目

   "autoload": {
    "psr-4": {
        "App\\": "app/"
   },
   "classmap": [
        "database/seeds",
   "database/factories"
   ],
   "file": [
        "app/helpers.php"
   ]
   },

3. 运行 composer dump-autoload

$ composer dump-autoload
Generating optimized autoload files> Illuminate\Foundation\ComposerScripts::postAutoloadDump
> [[@php](https://learnku.com/users/10050)](https://learnku.com/users/10050) artisan package:discover --ansi
Discovered Package: facade/ignition
Discovered Package: fideloper/proxy
Discovered Package: laravel/tinker
Discovered Package: laravel/ui
Discovered Package: nesbot/carbon
Discovered Package: nunomaduro/collision
Package manifest generated successfully.
Generated optimized autoload files containing 4053 classes

4. 最后刷新页面提示找不到自定义函数，laravel6.2版本
   谢谢