An example of a Command (from CommandBus), with default values

command_with_defaults.php

<?php

use Assert\Assertion;

class RegisterNewMember
{
    public $email;
    public $subscribeToNewsletter = true;
    
    public function __construct($email, $subscribeToNewsletter = null)
    {
        Assertion::email(email);
        $this->email = (string) $email;
        
        if (false === $subscribeToNewsletter) {
            $this->subscribeToNewsletter = false;
        }
    }
}