if $userList = [
                    ['user_nm' => 'A' , 'age' => 15],
                    ['user_nm' => 'B' , 'age' => 16],
                ];
/** @var User[] */
public array $userList;

// then  get_class($this->userList[0]) === User::class;
                

@separator
// if ?numbers="123,456,789"
/** @var int[] @separator ","  */
public array $numbers;

// then  $numbers = [123,456,789];
// if /** @var string[] @separator ","  */
// then  $numbers = ['123','456','789'];

// if ?number="123"
/** @ParamName("number") or @ParamName(number) or @ParamName('number')   */
public int $no;

// then  $this->no = 123;

// if $db = [ 'usr_nm' => 'seungtae.yoo' ];

/** @Column('usr_nm') or @Column(anyString = 'user_nm')   */
public string $userName;

// then  $this->userName = "seungtae.yoo";

<?php
// formData from Http Request
$_REQUEST = [
    'name' => 'styoo',
    'age' => '35'
];

class Controller
{
    // converting array data into DTO.
    public function example()
    {
        $mapper = new DataTransferObjectMapper();
        /** @var User $user */
        $user = $mapper->mapping($_REQUEST, User::class)->getClass();
        if ($mapper->hasErrors()) throw new Exception(var_export($mapper->getErrors(), true));
        $user->getName() === 'styoo';
        $user->getAge() === 35;
    }

    // If there is a provider layer in the framework,
    // you can apply this mapper to implement it like a Command Object.
    public function index(User $user)
    {
        if ($user->hasErrors()) throw new Exception(var_export($user->getErrors(), true));

        $user->getName() === 'styoo';
        $user->getAge() === 35;
    }
}

// Inheritance is only necessary when used as a command object.
class User extends CommandObject
{
    private string $name;
    private int $age;

    public function getName(): string
    {
        return $this->name;
    }

    public function getAge(): int
    {
        return $this->age;
    }

    protected function rule(): array
    {
        return ['name' => ['required'], 'age' => ['required', 'int']];
    }
}