Dúvida refactor DataMapper

1.random_database_access_class.php

<?php

// Isso é o que tem hoje
class Random
{
    // Este é o único atributo que essas classes random tem =(
    private $db;
    
    public function __construct(Db $db)
    {
        $this->db = $db;
    }
 
    // Users
    public function getUserById($id)
    {
        $sql = "SELECT * FROM pqp_users WHERE id = :id"; // Pra ser sistema legado, a table tem que ter prefixo HUE...
        
        $stmt = $this->db->prepare($sql);
        
        if (! $stmt->execute(["id" => $id])) {
            throw new RuntimeExeption("Fuuu..");
        }
        
        $result = $stmt->fetch();
        
        return $result;
    }
    
    // Posts (WTF?!)
    public function getRecentPosts($limit)
    {
        $sql = "SELECT * FROM pqp_posts ORDER BY created_at DESC LIMIT {$limit}"; // Pra ser sistema legado, a table tem que ter prefixo HUE...
        
        $stmt = $this->db->prepare($sql);
        
        if (! $stmt->execute()) {
            throw new RuntimeExeption("Fuuu..");
        }
        
        $result = $stmt->fetchAll();
        
        return $result;
    }
}

2.UserDataMapper.php

<?php

class User
{
    private $id;
    private $name;
    private $email;
    
    public function __construct($name, $email)
    {
        $this->name = $name;
        $this->email = $email;
    }
    
    /* GETTERS E SETTERS */
}

class UserMapper
{
    private $pdo;
    
    public function __construct(PDO $pdo)   
    {
        $this->pdo = $pdo
    }
    
    public function getById($id)
    {
        $stmt = $this->pdo->prepare(
            "SELECT *
             FROM pqp_users
             WHERE id = :id"
        );
        $stmt->bindParam(":id", $id, PDO::PARAM_INT);
        $stmt->setFetchMode(PDO::FETCH_CLASS|PDO::PROPS_LATE, "User");
        
        if (! $stmt->execute()) {
            // Exception...
        }
        
        return $stmt->fetch();
    }
}

// Exemplo de uso
try {
    $pdo = new PDO(...);
} catch (PDOException $e) {
  // ... 
}

$userMapper = new UserMapper($pdo);
$user = $userMapper->getById(1);

print_r($user);

3.PostDataMapper.php

<?php

// Faz sentido fazer isso???
class Post
{
    private $id;
    private $title;
    private $body;
    private $created_at;
    private $updated_at;
    
    public function __construct($title, $body)
    {
        $this->title = $title;
        $this->body = $body;
    }
    
    /* GETTERS E SETTERS */
}

class PostMapper
{
    private $pdo;
    
    public function __construct(PDO $pdo)   
    {
        $this->pdo = $pdo
    }
    
    public function getLastCreated($limit)
    {
        $stmt = $this->pdo->prepare(
            "SELECT *
             FROM pqp_posts
             ORDER BY created_at DESC
             LIMIT {$limit}"
        );
        
        $stmt->setFetchMode(PDO::FETCH_CLASS|PDO::PROPS_LATE, "Post");
        
        if (! $stmt->execute()) {
            // Exception...
        }
        
        return $stmt->fetchAll();
    }
}

//Exemplo
$postMapper = new PostMapper($pdo);
$recentPosts = $postMapper->getLastCreated(10);

print_r($recentPosts);