/** @var \TYPO3\CMS\Extbase\SignalSlot\Dispatcher $signalSlotDispatcher */
$signalSlotDispatcher = \TYPO3\CMS\Core\Utility\GeneralUtility::makeInstance(
    'TYPO3\\CMS\\Extbase\\SignalSlot\\Dispatcher'
);
$signalSlotDispatcher->connect(
    'TYPO3\\CMS\\Core\\Resource\\ResourceStorage',
    'postFileAdd',
    'foo\Typo3_Hook_Upload', 'postFileAdd'
);