note 98577 added to language.variables.scope

If you use __autoload function to load classes' definitons, beware that "static local variables are resolved at compile time" (whatever it really means) and the order in which autoloads occur may impact the semantic. For example if you have: <?php class Singleton{ static public function get_instance(){ static $instance = null; if($instance === null){ $instance = new static(); } return $instance; } } ?> and two separate files A.php and B.php: class A extends Singleton{} class B extends A{} then depending on the order in which you access those two classes, and consequently, the order in which __autoload includes them, you can get strange results of calling B::get_instance() and A::get_instance(). It seems that static local variables are alocated in as many copies as there are classes that inherit a method at the time of inclusion of parsing Singleton. ---- Server IP: 69.147.83.197 Probable Submitter: 195.88.186.3 ---- Manual Page -- http://www.php.net/manual/en/language.variables.scope.php Edit -- https://master.php.net/note/edit/98577 Del: integrated -- https://master.php.net/note/delete/98577/integrated Del: useless -- https://master.php.net/note/delete/98577/useless Del: bad code -- https://master.php.net/note/delete/98577/bad+code Del: spam -- https://master.php.net/note/delete/98577/spam Del: non-english -- https://master.php.net/note/delete/98577/non-english Del: in docs -- https://master.php.net/note/delete/98577/in+docs Del: other reasons-- https://master.php.net/note/delete/98577 Reject -- https://master.php.net/note/reject/98577 Search -- https://master.php.net/manage/user-notes.php