Letting the server recalculate a fixed value over and over again, is lazy. Simply calculate the fixed value once yourself. Add a comment if you would like to clarify a given value.

Incorrect:

setcookie('language', $code, time() + 60 * 60 * 24 * 30, '/', $request->Server['HTTP_HOST']);


Correct:

setcookie('language', $code, time() + 2592000, '/', $request->Server['HTTP_HOST']);


With a comment. Even better!

// Cookie expires in 60 seconds * 60 minutes * 24 hours * 30 days = 2592000 seconds
setcookie('language', $code, time() + 2592000, '/', $request->Server['HTTP_HOST']);