我刚到拉腊维尔。
我一直收到这个语法错误：

Symfony\Component\Debug\Exception\FatalThrowableError
syntax error, unexpected '.'

这句话是这样的：

$post = .\DB::table('posts')->where('slug', $slug)->first();

下面是无法正常工作的完整代码：

<?php

namespace App\Http\Controllers;

class PostsController extends Controller

{
  public function show($slug)
  {
    $post = .\DB::table('posts')->where('slug', $slug)->first();

    dd($post);

     // This was to simulate a database
     // $posts = [
     //   'my-first-post' => 'Hello This is my first blog post',
     //   'my-second-post' => 'Hello This is my second blog post',
     // ];

     // if it doesn't exist then throw this error:
     if (! array_key_exists($post, $posts)){
       abort(404, 'Sorry, that post was not found.');
     }

     // return this view:
      return view('post', [
        'post' => $posts[$post]
      ]);
  }

}

我到底错过了什么！？
谢谢