Laravel Как использовать переменные из другого файла

вариантов много, например так

MainController.php

<?php
namespace App\Http\Controllers;
use App\Http\Controllers\Controller;
use Illuminate\Http\Request;
use Illuminate\Foundation\Auth\AuthenticatesUsers;
use Auth;
use Illuminate\Foundation\Auth\User;
class MainController extends Controller
{
    public $table_name = 'server_1_users';
    public function doSomething()
    {
        $user = new User($this->table_name);
    }
}

User.php

<?php
namespace App;
use Illuminate\Notifications\Notifiable;
use Illuminate\Contracts\Auth\MustVerifyEmail;
use Illuminate\Foundation\Auth\User as Authenticatable;
use App\Http\Controllers\MainController;
class User extends Authenticatable
{
    public $table;
    public function __construct($table_name)
    {
      $this->table = $table_name;
    }
}

или так

MainController.php

<?php
namespace App\Http\Controllers;
use App\Http\Controllers\Controller;
use Illuminate\Http\Request;
use Illuminate\Foundation\Auth\AuthenticatesUsers;
use Auth;
use Illuminate\Foundation\Auth\User;
class MainController extends Controller
{
    public static $table_name = 'server_1_users';
}

User.php

<?php
namespace App;
use Illuminate\Notifications\Notifiable;
use Illuminate\Contracts\Auth\MustVerifyEmail;
use Illuminate\Foundation\Auth\User as Authenticatable;
use App\Http\Controllers\MainController;
class User extends Authenticatable
{
    public $table;
    public function __construct()
    {
      $this->table = MainController::$table_name;
    }
}