For running J!5.1 you must https://fabrikar.com/forums/index.php?wiki/update-from-github/ or include the new file manually https://fabrikar.com/forums/index.php?threads/joomla-5-1-and-fabrik-cannot-find-files-error.54473/post-285151 See also Announcements
Please see our announcement here.
require_once('/full/path/to/your/file.php');
return yourFunc($data);
function yourFunc($data) {
// do whatever, probably involving $data
return $whatever;
}
require_once JPATH_ROOT . '/some/folder/mystuff.php';
$myClass = new myClass;
return $myClass->doSomething();