Sessions, self defeating?

[monkeytooth]

I don't know if this is a self defeating concept or not. One of the people I am coding with added this line to the top of the index file

if(!isset($_SESSION)) {session_start();}

 

for some reason that doesn't make sense to me, would that be a self defeating way of starting a session? don't you need to have it just as session_start(); no matter what and not wrapped in a if-else?

[ignace]

In some bad designed applications people use this technique to verify wether or not session has already been started. Normally you don't check _SESSION but session_id() instead as when session's hasn't yet been started session_id() will return ""

[monkeytooth]

Thats what I was figuring, But couldn't find anything one way or another on something similar to the effect of the line I originally gave. So I thought I would come and ask. Thank you

[ignace]

For example if your application has different sources that all may use sessions then at some point a source may rely on sessions and thus writing something like:

 

$_SESSION['datakey'] = 'datavalue';

 

Now the line

 

if (!isset($_SESSION)) { session_start(); }

 

Evaluates false and session's does not get started the array _SESSION gets filled with data but is not persisted between requests.