Question

I have many session vars. Should I use this

$_SESSION[SessionHelper::ROUTING] = SessionHelper::MODULE_A;

class SessionHelper {
   const ROUTING = 'SessionHelper.routing';
   const MODULE_A = 1;
   const MODULE_B = 2;
}

or this?

$_SESSION['routing'] = 1;

The first seems to be maintenanable but hard to read in some case. For example:

if(isset($_SESSION[SessionHelper::ROUTING]) && 
   $_SESSION[SessionHelper::ROUTING] = SessionHelper::MODULE_A) {
....

The second is quite short but if there is a change, we must change everywhere the “routing” exist. Further more, it can pollute the session scope because the ‘routing’ string is so common.

Answer 1

If you really need a session helper (say: if you really need a class abstracting a PHP session), then use the $_SESSION superglobal only inside that class (and not outside). So you have the superglobal encapsulated and you can replace it with test-doubles.

Next to that, this depends on the use of the session store. I bet it’s highly dynamic, so I don’t see much value in specifying array keys as constants first w/o any futher use (e.g. valid/invalid key checks aren’t done).

I hope this does not sound harsh, because it’s not meant so. Please ask if something is unclear or you have further questions. As jprofitt wrote in his answer, preventing magic numbers is something very useful, but I’m not totally convinced, that you actually introduce them here or if it isn’t just dynamic properties (especially if you create a session store class).