Hi Rowan, Rowan wrote: > For that to work, it would require the variable to be captured by > reference, not value. > ... > The only way for it to work would be using capture by reference (not > supported by the proposed short syntax):
I wrote about this before. Some of the words in the RFC are, in my opinion, quite inaccurate: Danack wrote in https://news-web.php.net/php.internals/117938 : > Those statements are true for scalar values. They are not true for objects: With automatic capturing of variables, for the code example I gave the user would want the variable to be captured, and to them it looks like it should be, but because of an optimization it is not. When the code doesn't work as they expect it to, the programmer is likely to add a var_dump to try to see what is happening. Which makes it look like their code 'should' work, as their resource object is still alive. > In fact, the "optimisation" is in my opinion a critical part of the > semantics, to avoid the opposite problem: As I said, I think that problem is a lot easier to explain "either use long closures or change your variable name if you don't want it captured." than trying to explain "yes, the variable is referenced inside the closure, but it's not captured because you aren't reading from it". cheers Dan Ack For this code, comment the var_dump in/out to affect the lifetime of the object. class ResourceType { public function __destruct() { echo "Resource is released.\n"; } } function get_callback() { $some_resource = new ResourceType(); $fn = fn() { // // why is my lock released? var_dump($some_resource); // "Free that resource" $some_resource = null; }; return $fn; } $fn = get_callback(); echo "Before callback\n"; $fn(); echo "After callback\n"; // Without var_dump Resource is released. Before callback After callback // With var_dump Before callback object(ResourceType)#1 (0) { } After callback Resource is released. -- PHP Internals - PHP Runtime Development Mailing List To unsubscribe, visit: https://www.php.net/unsub.php
