不正なプロパティ名を持つ PHP オブジェクトにアクセスするにはどうすればよいですか?

$object->todo-items; // Syntax error

$object['todo-items']; // Accesses the "todo-items" property

$propertyName = 'todo-items';
$object->{$propertyName}; // Accesses the "todo-items" property

$array = (array) $object; // Converts the object to an array
$array['todo-items']; // Accesses the "todo-items" property

public function toArray()
{
    $array = array();
    foreach ($this->_data as $key => $value) {
        if ($value instanceof StdClass) {
            $array[$key] = $value->toArray();
        } else {
            $array[$key] = $value;
        }
    }
    return $array;
}