Email Sender sınıfı için Loose Coupling örneği

loose_coupling.php

<?php

interface UserProviderInterface {

    public function findUserById($id);

}

class UserProvider implements UserProviderInterface {

    private $db;

    public function __construct(MySQLConnection $db)
    {
        $this->db = $db;
    }
    
    public function findUserById($id)
    {
        return $this->db->execute('SELECT * FROM users WHERE id = ?', array($id));
    }

}

class EmailSender {

    private $users;
    
    public function __construct(UserProviderInterface $users)
    {
        $this->users = $users;
    }
    
    public function send($id, $subject, $message)
    {
        $user = $this->users->findUserById($id);
        // E-Posta gönderme işlemi
    }

}