Call to a member function getPaginate() on a non-object

I'm new to laravel framwork , and I'm coding my first web app

and getting the following error

 FatalErrorException in PersonController.php line 26:
Call to a member function getPaginate() on a non-object

this is my Controller

   <?php

namespace App\Http\Controllers; 
use App\Repositories\PersonRepository;

class PersonController extends Controller
{
    protected  $personRepo ;
    protected  $nbrPerPage = 4 ;


    public  function  _construct(PersonRepository $personRepository)
    {
        $this->personRepo = $personRepository ;
    }
    public function index()
    {
        $persons = $this->personRepo->getPaginate(nbrPerPage);
        $links = $persons->setPath('')->render();

        return view('index', compact('persons', 'links'));
    }

    public function create()
    {

    }


    public function store()
    {

    }


    public function show($id)
    {
        //
    }


    public function edit($id)
    {
        //
    }


    public function update($id)
    {
        //
    }


    public function destroy($id)
    {
        //
    }


}

and this my repository class

<?php
namespace  App\Repositories ;
use App\Person ;
use App\User;


class PersonRepository {

  protected  $person ;
    public function  _construct (Person $person)
    {
        $this->$person = $person  ;
    }


    public  function  getPaginate($n)
    {

        return $this->person-> paginate($n) ;
    }


 }

from Newest questions tagged laravel-5 - Stack Overflow http://ift.tt/1JToIXG
via IFTTT