依赖注入，是否可以注入“包装”对象？

I have a wrapper class, to get email templates:

class Email
{
    public function getWellcome()
    {
        return 'body';
    }

    public function getRegistration()
    {
        return 'body';
    }

    public function getCommentSent()
    {
        return 'body';
    }
}

for my class, it is just easy to pass it:

class User
{
    private $email;

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

    public function asd()
    {
        $m = $this->email->getRegistration();
        MailHandler::send($m);
    }
}

new User(new Email());

but I feel somewhat violating LoD. What if I refactor it like that:

class User
{
    private $registrationEmail;

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

    public function asd()
    {
        $m = $this->registrationEmail;
        MailHandler::send($m);
    }
}

new User(new Email()->getRegistration());

this looks a bit nicer, but I would then need to inject all neccessary objects one by one, not to mention what if I need to cycle through all emails? Which way is preferable?

The way I would do it look something like this:

$user = new User;
$user->asd(new Template('/path/to/registration/template.html.twig'));

As I see it, you have two issues:

• the Email class has multiple reasons to change (and seems mislabeled)
• your User class has a dependency, that isn't actually required most of time

P.S.
I am not all that convinced, that your User class should be responsible for sending registration confirmation emails.