a.php

<?php
use Phalcon\Mvc\View;

$di = new \Phalcon\Di\FactoryDefault();

$di->set('view',function(){
    $view=new \Phalcon\Mvc\View\Simple;
    $view->registerEngines([
        '.volt'=>'Phalcon\Mvc\View\Engine\Volt' // this will produce error beacause it will be passed here as string https://github.com/phalcon/cphalcon/blob/2.1.x/phalcon/di.zep#L235(name parameter)
    ]);
    return $view;
});

var_dump($di->get('view'));