introduction-php-reflection-reflection-method-create-controller.php

<?php

class UserRepository
{ }

class UserController {
    private $userRepository;

    public function __construct(UserRepository $repository)
    {
        $this->userRepository = $repository;
    }
}

$constructorReflected = new ReflectionMethod(UserController::class, '__construct');
$constructorParameters = $constructorReflected->getParameters();

$argumentsToConstruct = [];

foreach ($constructorParameters as $parameter) {
    $name = $parameter->getClass()->name;
    var_dump($name);
    // string(14) "UserRepository"

    $instance = new $name();
    var_dump($instance);
    // object(UserRepository)#3 (0) {
    //}

    $argumentsToConstruct[] = $instance;
}

$userController = new UserController(...$argumentsToConstruct);
var_dump ($userController);
// object(UserController)#4 (1) {
//  ["userRepository":"UserController":private]=>
//  object(UserRepository)#3 (0) {
//  }
//}