Error in log path when changing Application name

[bgougent]

When in the index.php of CI the path to the application is changed
$application_folder = 'new_applicationfolder';
An error occured in file Ciqrcode at position 18
changing the entry to
var $errorlog = 'new_applicationfolder/logs/'; problem is solved.
Can the code be altered to a dynamic var that follows the global change?