DateTime::toString

public function toString($modifier = null)
{
	$date = $this->value;
	$options = $this->getOptions($modifier);
	$format = $options['format'];
	if($date instanceof TypeDate)
	{
		$interfaceLanguage = LANGUAGE_ID;
		$templateLanguage = DataProviderManager::getInstance()->getRegionLanguageId();
		if($templateLanguage != $interfaceLanguage)
		{
			Loc::setCurrentLang($templateLanguage);
		}
		$result = FormatDate($format, $date->getTimestamp());
		if($templateLanguage != $interfaceLanguage)
		{
			Loc::setCurrentLang($interfaceLanguage);
		}

		return $result;
	}

	if(!$date)
	{
		$date = '';
	}
	return $date;
}