Laravel: Avoid to create istance of a model with a constructor in the controller

I beautiful people,

another question for a laravel novice: for now I'm following a course of laravel 4 and the teacher did a code refactoring and introduced a magic method constructor in the controller

class UtentiController extends BaseController {

protected $utente;
public function __construct(Utenti $obj) {

    $this->utente = $obj;

}

public function index() {

    $utenti = $this->utente->all();

    return View::make('utenti.index', ["utenti" => $utenti]);

}

public function show($username) {

    $utenti = $this->utente->whereusername($username)->first(); //select * from utenti where username = *;

    return View::make('utenti.singolo', ["utenti" => $utenti]);
}

public function create() {

    return View::make('utenti.create');

}


public function store() {

    if (! $this->utente->Valido( $input = Input::all() ) ) {

        return Redirect::back()->withInput()->withErrors($this->utente->messaggio);

    }

    $this->utente->save();

    return Redirect::route('utenti.index');

}

}

thanks to this code i can avoid every time to create a instance of the model Utenti:

protected $utente;
public function __construct(Utenti $obj) {

    $this->utente = $obj;

}

now i can access to the database with this simple approach:

/* now i can access to the database simply use this method */

$this->utente->all();

---

before this, i had to:

$utente = new Utente;

$utente::all();

---

this type of tecnique have a name? (is a pattern?). Hovewer,i know what does he do: every time the controller is invoked automatically generates an instance of the User class (model) and applies an alias (reference) attribute protected $utente;

that's right? Thanks for everything.

P.S: that's the code of my User Layer model called "Utenti":

class Utenti extends Eloquent {

public static $regole = [

    "utente" => "required",
    "password" => "required"

];

public $messaggio;

public $timestamps = false;

protected $fillable = ['username','password'];

protected $table = "utenti";


public function Valido($data) { 


    $validazione = Validator::make($data,static::$regole);


    if ($validazione->passes()) return true;

    $this->messaggio = $validazione->messages();

    return false;

}

}