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I'm trying to use a closure as a callback once a thread is done running. However I'm running into what seems to be a limit/failure of PHP or the pthread extension.

My dev stack is running on Win7 x64 with PHP 5.5.3 x86 TS, pthread version 0.44.

The following code works :

class Test
{
    public $callbackVar;
}

$test = new Test();

$callbackVar = function()
{
    echo "Callback var invoked.";
};

$test->callbackVar = $callbackVar;
$test->callbackVar->__invoke();

But as soon as I derive Test from Thread, running the script gives an error :

class Test extends Thread
{
    public $callbackVar;
    public function run() { }
}

$test = new Test();

$callbackVar = function()
{
    echo "Callback var invoked.";
};

$test->callbackVar = $callbackVar;
// assert() returns true
assert($test->callbackVar === null);
$test->callbackVar->__invoke();

With the following output 

Fatal error: Call to a member function __invoke() on a non-object

Anyone ever had this issue ? Any possible workaround ? I'd rather not use eval if possible... I've tried many workarounds, such as rewrapping into another closure, using a ReflectionFunction, ... nothing cuts it.

T. Fabre
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  • What PHP version are you using? – MisterBla Aug 27 '13 at 08:38
  • Updated question, forgot about that... – T. Fabre Aug 27 '13 at 08:40
  • I made an [3v4l](http://3v4l.org/RnEgH) of your code. Between 5.3 and 5.5.2 there are no errors. Not sure what'd going on then. – MisterBla Aug 27 '13 at 08:41
  • The failing version is http://3v4l.org/vFXh6 but it seems 3v4l does not have the pthread lib. – T. Fabre Aug 27 '13 at 08:42
  • Why not try calling run? public function run() { $callback = $this->callbackVar; $callback(); } – MisterBla Aug 27 '13 at 08:47
  • Oh I did. But $this->callbackVar is always null, seems the closure is getting never assigned. $test->callbackVar = $callbackVar just fails silently, var_dump($test->callbackVar) returns null. Whether I invoke from withing run() or outside of it as in my exemple, I get the same error. – T. Fabre Aug 27 '13 at 08:51
  • Tried using a setter function that takes a closure as its argument? `public function setCallback($closure) { $this->callbackVar = $closure; } $test->setCallback(function() { echo 'Callback invoked.'; });`. Sorry for the lack of newlines. Comments don't approve. – MisterBla Aug 27 '13 at 08:53
  • http://pastebin.com/Tri8RjUR This is what I've tried, with no success so far. – T. Fabre Aug 27 '13 at 09:19
  • Not sure if I can help you then, I'm not familiar with pthreads. Sorry. – MisterBla Aug 27 '13 at 09:20

1 Answers1

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Zend does not allow you to serialize closure objects.

So it's not something you should try to work around, possibly at some time in the future Zend will allow serialization of Closures, pthreads will not require changes at that time.

You'll just have to do it the old fashioned way ...

Joe Watkins
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