Req #52215 [Opn->Dup]: Add var_ref_count()

Edit report at https://bugs.php.net/bug.php?id=52215&edit=1 ID: 52215 Updated by: nikic@php.net Reported by: dev at alepe dot com Summary: Add var_ref_count() -Status: Open +Status: Duplicate Type: Feature/Change Request Package: Variables related Operating System: Any PHP Version: 5.3.3RC1 Block user comment: N Private report: N New Comment: Marking as duplicate, per ky's last comment. Previous Comments: ------------------------------------------------------------------------ [2014-08-15 03:39:51] ky dot patterson at adlinkr dot com This cannot be done with a function. The act of passing a variable to a function (by reference or by value) changes or replaces the variable's zval. So the refcount you will get is inaccurate -- and not just "off by 1", because zend may copy the zval before it is passed to your function. There are several other bugs that either ask for a refcount function, or ask for debug_zval_dump to be "fixed" to support pass-by-reference, and all of them are not workable AFAIK: https://bugs.php.net/bug.php?id=40011 Request for refcount function https://bugs.php.net/bug.php?id=52215 Add var_ref_count() https://bugs.php.net/bug.php?id=66455 Missing function to determine refcount of variables directy https://bugs.php.net/bug.php?id=53895 debug_zval_dump should be by ref I *think* the solution is actually to add new language constructs, and I have opened a bug to discuss that: https://bugs.php.net/bug.php?id=67847 ------------------------------------------------------------------------ [2012-09-23 22:09:51] chrisw at networkm dot co dot uk The problem (such as it is) that this issue creates is larger in PHP 5.4. Because call-time pass by reference now causes a fatal error, debug_zval_dump() is now completely pointless (the data it can provide can obtained from var_dump()). Either it should be removed and something like var_ref_count() should be added, or it should be altered to take it's argument by reference. ------------------------------------------------------------------------ [2011-05-09 19:07:17] thegreatall at gmail dot com I recently wrote a simple modification to the php source, which returns the number of references linked to a variable. It does suffer from the same problem that debug_zval_dump suffers from, but it is simply always +1 than what you expect. Aadding a note in the documentation saying "The value will always be 1 more than the actual reference count." or just -1 from the returned value should work. If there's even a chance that this would be reviewed and possibly added into php's source, I would be happy to make a patch for it. This function may not seem critical, but I developed a framework that does allot of class recycling and it would be nice to have the ability to figure out what variables it can release, and a function like this or what I wrote would be HUGE in terms of memory management. A conversion script I wrote uses upwards of 1-3 gigs of ram if I recycle variables, but I could reduce that number to <10 megs if I could figure out what variables are free'able. The workaround I have to work with now is to either "guess" what isn't being used (which is almost always wrong) or to not use any object recycling which is alot slower because it needs to initiate a new object every time, and you can have 2 different objects to the same data (which the huge downside to it is that there can be 2 objects for the same record/data). ------------------------------------------------------------------------ [2010-07-01 13:44:40] derick@php.net This won't work, for the same reason that debug_zval_dump() is flawed. By passing a variable to a function, you mess with the refcount/is_ref values. Xdebug's xdebug_debug_zval() (http://xdebug.org/docs/all_functions#xdebug_debug_zval) goes around that by looking up the symbol directly (but it doesn't support array elements directly). ------------------------------------------------------------------------ [2010-07-01 03:49:32] dtajchreber@php.net http://www.php.net/manual/en/function.debug-zval-dump.php ------------------------------------------------------------------------ The remainder of the comments for this report are too long. To view the rest of the comments, please view the bug report online at https://bugs.php.net/bug.php?id=52215 -- Edit this bug report at https://bugs.php.net/bug.php?id=52215&edit=1