Сергей Шлоков

может я хочу поредактировать статический сниппет какого-нибудь стороннего модуля

Вот так безопасно

$schemaFile = MODX_CORE_PATH . 'components/modextra/model/schema/modextra.mysql.schema.xml';
if (is_file($schemaFile)) {
	$schema = new SimpleXMLElement($schemaFile, 0, true);
	if (isset($schema->object)) {
		foreach ($schema->object as $object) {
			$objName = (string)$object['class'];
			$objects[] = $objName;
			// Indexes
			foreach ($object->index as $index) {
				$indexes[$objName][] = (string) $index['name'];
			}
		}
	}
	unset($schema);
} else {
	$modx->log(modX::LOG_LEVEL_ERROR, 'Could not get classes from schema file.');
}
//Работаем с таблицами
foreach ($objects as $tmp) {
   $manager->createObjectContainer($tmp);
   ...
}
//Работаем с индексами
foreach ($ClassIndexes as $class=>$indexes) {
	foreach($indexes as $index) {
		$manager->addIndex($class,$index);
	}
}

$schemaFile = MODX_CORE_PATH . 'components/modextra/model/schema/modextra.mysql.schema.xml';
$objects = array();
if (is_file($schemaFile)) {
	$schema = new SimpleXMLElement($schemaFile, 0, true);
	if (isset($schema->object)) {
		foreach ($schema->object as $object) {
			$objects[] = (string)$object['class'];
		}
	}
	unset($schema);
} else {
	$modx->log(modX::LOG_LEVEL_ERROR, 'Could not get classes from schema file.');
}