OOP visibility and type hinting examples

Autoloader.php

<?php
class Autoloader
{
    /**
     * @param string $className
     */
    public function autoload($className)
    {
        require str_replace('\\', '/', $className) . '.php';
    }

    public function register()
    {
        spl_autoload_register([$this, 'autoload']);
    }
}

Employee.php

<?php
namespace Company;

class Employee extends Person
{
    /** @type Money */
    protected $salary;

    /**
     * @param string  $name
     * @param integer $age
     * @param Money   $salary
     */
    public function __construct($name, $age, Money $salary)
    {
        parent::__construct($name, $age);
        $this->salary = $salary;
    }

    /**
     * @param string $lastName
     */
    public function setLastName($lastName)
    {
        $this->lastName = $lastName;
    }
}

index.php

<?php
require 'Autoloader.php';

use Company\Person;
use Company\Employee;
use Company\Money;

$autoloader = new Autoloader();
$autoloader->register();

$luis = new Person('Luis', 34);
$luis->name;
echo $luis->getAge();

$enrique = new Employee('Enrique', 'Cincuenta', new Money(10000, 'MXN'));
$enrique->setLastName('Hernández');
echo $enrique->getAge();

$gregorio = new Employee('Gregorio', 20, new Money(20000, 'USD'));
echo $gregorio->getAge();

Money.php

<?php
namespace Company;

class Money implements CastsToJson
{
    use ProvidesJsonEncoding;

    /** @type integer */
    protected $amount;

    /** @type string */
    protected $currency;

    /**
     * @param integer $amount
     * @param string  $currency
     */
    public function __construct($amount, $currency)
    {
        $this->amount = $amount;
        $this->currency = $currency;
    }
}

Person.php

<?php
namespace Company;

class Person
{
    /** @type string */
    public $name;

    /** @type string */
    protected $lastName;

    /** @type integer */
    private $age;

    /**
     * @param string  $name
     * @param integer $age
     */
    public function __construct($name, $age)
    {
        $this->name = $name;
        $this->age = $age;
    }

    /**
     * @return integer
     */
    public function getAge()
    {
        return $this->age;
    }
}