InterFaces PHP-Rules

<?php


interface Logger
{
    public function execute($message);
}

class LogToFile implements Logger
{
    public function execute($message)
    {
        var_dump('Log that message: file '.$message);
    }
}


class LogToDatabase implements Logger
{
    public function execute($message)
    {
        var_dump('Log that message database: '.$message);
    }
}


class UserController
{
    protected $logger;

    public function __construct(Logger $logger)
    {
        $this->logger=$logger;
    }

    public function show()
    {
        $user='Asad';

        $this->logger->execute($user);
    }
}

$user=new UserController(new LogToFile);
$user->show();