note 81458 added to language.oop5.decon

While experimenting with destructs and unsets in relation to memory usage, I found what seems to be one useful way to predict when __destruct() gets called... call it manually yourself. I had previously assumed that explicitly calling unset($foo) would cause $foo->__destruct() to run implicitly, but that was not the behavior I saw (php 5.2.5). The destructors weren't running until the script ended, even though I was calling unset($foo) in the middle of my script. So, having $foo->__destruct() unset all of $foo's component objects was not helping my memory usage since my explicit unset($foo) was _not_ triggering $foo->__destruct()'s cleanup steps. Interestingly, what _did_ appear to happen is that calling unset($bar) from inside a destructor like $foo->__destruct() _DID_ cause $bar->__destruct() to be implicitly executed. Perhaps this is because $bar has a "parent" reference of $foo whereas $foo does not, and the object destruction behaves differently... I don't know. Lastly, even after explicitly calling $foo->__destruct() (even when it had "unset($this);" inside it), the reference to the $foo object remained visible. I had to still explicitly call unset($foo) to get rid of it. So, my advice based on the behavior I saw in my experiments: - always unset($bar) your class's component objects from inside that class's __destruct() method; no explicit component destructor calls seem to be required other than those unsets, though. - always explicitly call $foo->__destruct() in your code that _uses_ your class - always explicitly follow $foo->__destruct() with unset($foo). This seems to be the best cleanup approach to take. Just for my own sanity, I also will always keep an unset($this) at the end of each __destruct() method. ---- Server IP: 69.147.83.197 Probable Submitter: 38.99.98.18 ---- Manual Page -- http://www.php.net/manual/en/language.oop5.decon.php Edit -- https://master.php.net/note/edit/81458 Del: integrated -- https://master.php.net/note/delete/81458/integrated Del: useless -- https://master.php.net/note/delete/81458/useless Del: bad code -- https://master.php.net/note/delete/81458/bad+code Del: spam -- https://master.php.net/note/delete/81458/spam Del: non-english -- https://master.php.net/note/delete/81458/non-english Del: in docs -- https://master.php.net/note/delete/81458/in+docs Del: other reasons-- https://master.php.net/note/delete/81458 Reject -- https://master.php.net/note/reject/81458 Search -- https://master.php.net/manage/user-notes.php