<?php

/**
 * Person
 *
 * Represents a person
 */
class Person
{
    const FORENAME = 'forename';
    const SURNAME = 'surname';

    /**
     * The person's forename
     *
     * @var string
     * @access private
     */
    private $forename;

    /**
     * The person's surname
     *
     * @var string
     * @access private
     */
    private $surname;

    /**
     * __construct
     *
     * @param string $forename the person's forename
     * @param string $surname the person's surname
     * @access public
     * @return void
     */
    public function __construct($forename, $surname)
    {
        $this->setForename($forename);
        $this->setSurname($surname);
    }

    /**
     * Set the forename
     *
     * @param string $forename the person's forename
     * @access public
     * @return void
     */
    public function setForename($forename)
    {
        $this->forename = (string) $forename;
    }

    /**
     * Set the surname
     *
     * @param string $surname the person's surname;
     * @access public
     * @return void
     */
    public function setSurname($surname)
    {
        $this->surname = (string) $surname;
    }

    /**
     * Get the person's forename
     *
     * @access public
     * @return string
     */
    public function getForename()
    {
        return $this->forename;
    }

    /**
     * Get the person's surname
     *
     * @access public
     * @return string
     */
    public function getSurname()
    {
        return $this->surname;
    }
}

$ibuildingsPeople = array();
$ibuildingsPeople[] = new Person('Yair', 'Spitzer');
$ibuildingsPeople[] = new Person('Gordon', 'Skinner');
$ibuildingsPeople[] = new Person('Paul', 'Matthews');

sortPeople($ibuildingsPeople);

/**
 * Sorts People by property
 *
 * @param array $people of Person objects
 * @param string $property the property of Person to search on
 * @access public
 * @return array the sorted array of People
 */
function sortPeople($people, $property = Person::SURNAME)
{
    // your code here...