RE: [PHP] Migrating pre-4.1 code to a post-4.1 server with regist er_globals on

> -----Original Message----- > From: Ford, Mike [LSS] [mailto:M.Ford@lmu.ac.uk] > Sent: Friday, June 20, 2003 2:57 AM > To: Johnson, Kirk; php-general@lists.php.net > Subject: RE: [PHP] Migrating pre-4.1 code to a post-4.1 server with > regist er_globals on > > > > -----Original Message----- > > From: Johnson, Kirk [mailto:kjohnson@zootweb.com] > > Sent: 19 June 2003 20:31 > > To: php-general@lists.php.net > > Subject: [PHP] Migrating pre-4.1 code to a post-4.1 server with > > register_globals on > > > > > > A heads-up to those who are moving old code with > > register_globals "on" to a > > server with a newer PHP version and register_globals still "on": > > > > In the old days, the rule was simple. For a session variable, > > whatever value > > was in the global variable at the end of the script was what > > was saved to > > the session, and that value was restored on the next page. > > > > Under a newer version of PHP, e.g., 4.3.2, this is no longer > > true in one > > case. Assume we have a session variable, 'a', that has been > > assigned some > > value: > > > > $a = 'someValue'; > > session_register('a'); > > > > Then > > > > unset($a); > > > > will unset the global variable, $a, but NOT the corresponding > > element in the > > two session arrays, $HTTP_SESSION_VARS and $_SESSION. > > Actually, this should only be true for versions 4.1.0 to > 4.2.3 -- the manual > page at http://uk.php.net/manual/en/ref.session.php > (admittedly a *long* way > down it and hidden under the "Examples" heading!) contains > this warning: > > "There is a defect in PHP 4.2.3 and earlier. If you register > a new session > variable by using session_register(), the entry in the global > scope and the > $_SESSION entry will not reference the same value until the next > session_start(). I.e. a modification to the newly registered > global variable > will not be reflected by the $_SESSION entry. This has been > corrected in PHP > 4.3." Please let me clarify what I am saying. The manual reference above is correct, *to a point*. In 4.3.2, when you *assign* to any one of the session variable $a, $HTTP_SESSION_VARS['a'], or $_SESSION['a'], you simultaneously *assign* to the other two. For example, $HTTP_SESSION_VARS['a'] = 'iguana'; simultaneously *assigns* 'iguana' to $a and $_SESSION['a']. However, unset($a) does NOT unset $HTTP_SESSION_VARS['a'] or $_SESSION['a'], with two results. One, the value of the session variable, $a, is no longer in sync with $HTTP_SESSION_VARS['a'] and $_SESSION['a']. Two, $a will have the value 'iguana' restored on the next session_start(). This is unexpected behavior and not explained in the manual, AFAIK. Kirk