PHP按一定标准排序对象数组？

class Person {
    public $name;
    public $age;

    public function __construct($name, $age) {
        $this->name = $name;
        $this->age = $age;
    }
}

$people = [
    new Person("Alice", 25),
    new Person("Bob", 30),
    new Person("Charlie", 20)
];

// 自定义比较函数，按照年龄升序排序
function compareByAge($person1, $person2) {
    return $person1->age - $person2->age;
}

usort($people, "compareByAge");

// 打印排序结果
foreach ($people as $person) {
    echo $person->name . " - " . $person->age . "\n";
}

Charlie - 20
Alice - 25
Bob - 30