Req #77537 [Ver->Csd]: Unexpected behavior, when using static in constructor

Edit report at https://bugs.php.net/bug.php?id=77537&edit=1 ID: 77537 Updated by: nikic@php.net Reported by: dirk dot gerigk at atraveo dot com Summary: Unexpected behavior, when using static in constructor -Status: Verified +Status: Closed Type: Feature/Change Request Package: Class/Object related Operating System: Windows 10 PHP Version: 7.2.14 -Assigned To: +Assigned To: nikic Block user comment: N Private report: N New Comment: I did end up writing that proposal (https://wiki.php.net/rfc/static_variable_inheritance). This means that as of PHP 8.1 the result will be as written in the "expected result". Previous Comments: ------------------------------------------------------------------------ [2021-02-18 16:58:19] nikic@php.net The problem is that we're caching the constructor (and a few magic methods) in the class entry, but end up storing the parent constructor there -- which is always going to be the same unless it uses static variables, thus nobody noticed. This is a bug, though I'm also increasingly tempted to write a proposal that changes the way we handle static variables in methods, and not use a separate static variable scope on inheritance. ------------------------------------------------------------------------ [2021-02-18 16:03:58] dirk dot gerigk at atraveo dot com I have tested in another way class A { public function test(){ static $test = 0; print (++$test); } public function __construct(){ $this->test(); } } class B extends A { public function __construct(){ parent::__construct(); } } class C extends A {} $a = new A; $a->__construct(); $b = new B; $b->__construct(); $c = new C; $c->__construct(); and the result is 121212 So, for now i will keep in mind: * dont mess with the constuctor of a class * do not use static variables in a constructor Thanks for the time and work ------------------------------------------------------------------------ [2021-02-18 16:02:33] nikic@php.net Oh, I missed that "new C" and "$c->__construct()" produce different results. Agree that this doesn't seem right. ------------------------------------------------------------------------ [2021-02-18 15:50:42] dirk dot gerigk at atraveo dot com Hi, what i dont get is the different behavior of the twice call $c = new C; $c->__construct(); the first line calles A::__construct and shows 5 the second lines calls then the method with a separate static and shows 1 So this statement is not valid here: "if the method is inherited, then it also gets separate static variables" If this statement is right, then the two calls have to have 1 and 2 as result, no 5 and 1, or? Normaly u dont call $c->__construct() on an existing object, but why is direct call of __construct so different? But thanks, for the reply. ------------------------------------------------------------------------ [2021-02-18 11:01:26] nikic@php.net In PHP, static variables are bound to a specific method -- if the method is inherited, then it also gets separate static variables. This means that C::__construct() has static variables independent of A::__construct(). I'm going to close this as a duplicate of bug #74198, because the behavior of static variables in methods and their interaction with inheritance is currently not documented. ------------------------------------------------------------------------ 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=77537 -- Edit this bug report at https://bugs.php.net/bug.php?id=77537&edit=1