PHP 5.4 이전에는 PHP 객체를 JSON으로 변환하려면 어떻게 해야 합니까?

<code class="php">$json = json_encode((array)$object);</code>

<code class="php">public function toArray()
{
    $array = (array) $this;
    array_walk_recursive($array, function (&$property) {
        if ($property instanceof Mf_Data) {
            $property = $property->toArray();
        }
    });
    return $array;
}</code>

<code class="php">public function toArray()
{
    $array = get_object_vars($this);
    unset($array['_parent'], $array['_index']);
    array_walk_recursive($array, function (&$property) {
        if (is_object($property) && method_exists($property, 'toArray')) {
            $property = $property->toArray();
        }
    });
    return $array;
}</code>