Doc #76104 [Ver->Csd]: Generator::next() causes yield to return null

Edit report at https://bugs.php.net/bug.php?id=76104&edit=1 ID: 76104 Updated by: cmb@php.net Reported by: alexey at kopytko dot com Summary: Generator::next() causes yield to return null -Status: Verified +Status: Closed Type: Documentation Problem Package: Scripting Engine problem PHP Version: 7.2.3 -Assigned To: +Assigned To: cmb Block user comment: N Private report: N New Comment: This bug has been fixed in the documentation's XML sources. Since the online and downloadable versions of the documentation need some time to get updated, we would like to ask you to be a bit patient. Thank you for the report, and for helping us make our documentation better. Previous Comments: ------------------------------------------------------------------------ [2018-03-16 17:33:45] cmb@php.net Automatic comment from SVN on behalf of cmb Revision: http://svn.php.net/viewvc/?view=revision&amp;revision=344528 Log: Fix #76104: Generator::next() causes yield to return null ------------------------------------------------------------------------ [2018-03-16 07:10:10] requinix@php.net next() and send() both advance the generator. That's how generators work. Using next(), explicitly or implicitly, means there's no way to pass a value back through the yield and thus the code will get null - just like when trying to get the return value from a function that doesn't return anything. ------------------------------------------------------------------------ [2018-03-16 06:44:11] alexey at kopytko dot com Description: ------------ foreach calls next() on a generator, which for some reason triggers send(null) on the generator. All previous versions are also affected: https://3v4l.org/bfg64#v560 First reported here: https://stackoverflow.com/q/37817315 Test script: --------------- $generator = (function () { for ($i = 0; $i < 5; $i += 1) { $answer = (yield $i * 2); echo "received: $answer\n"; } })(); foreach ($generator as $x) { echo "sending $x\n"; $generator->send($x); } Expected result: ---------------- sending 0 received: 0 sending 2 received: 2 sending 4 received: 4 sending 6 received: 6 sending 8 received: 8 Actual result: -------------- sending 0 received: 0 received: sending 4 received: 4 received: sending 8 received: 8 ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=76104&edit=1