class MyForm extends Nette\Application\UI\Form
{
    private $dep;

    public function __construct(Dep $dep)
    {
        parent::__construct();
        $this->dep = $dep;
        $this->addText('name');
        $this->onSuccess[] = $this->createUser;
    }

    public function createUser(Form $form)
    {
        $this->dep->...
    }
}

interface MyFormFactory
{
    /** @return MyForm */
    function create();
}


////////////////////////


class MyFormControl extends Nette\Application\UI\Control
{
    private $dep;

    public function __construct(Dep $dep)
    {
        parent::__construct();
        $this->dep = $dep;
    }

    protected function createComponentForm()
    {
        $form = new Nette\Application\UI\Form;
        $form->addText('name');
        $form->onSuccess[] = $this->createUser;
        return $form;
    }

    public function createUser(Form $form)
    {
        $this->dep->...
    }
}

interface MyFormControlFactory
{
    /** @return MyFormControl */
    function create();
}