PHP: call_user_func_array: pass by reference issue [duplicate]

Question

The below function generates error when a function contains referenced arguments eg:

function test(&$arg, &$arg2)
{
  // some code
}

Now I can not use call_user_func_array for above function, it will generate an error.

How to solve this problem?

I do need to use call_user_func_array.

Also assume that i don't know beforehand whether they are passed by reference or passed by value.

Thanks

It would be worth while for you to unaccept the current answer as it is quite literally wrong (not to mention has bad advice by abusing objects which changes the semantics of the problem completely): codepad.viper-7.com/j3GOps — ircmaxell
– ircmaxell, Commented Dec 1, 2011 at 17:22

Myles · Accepted Answer · 2009-12-15 07:47:00Z

22

When storing your parameters in the array, make sure you are storing a reference to those parameters, it should work fine.

Ie:

call_user_func_array("test", array(&param1, &param2));

answered Dec 15, 2009 at 7:47

Myles

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5 Comments

Sarfraz Over a year ago

but what if i don't know beforehand whether they are passed by reference or passed by value?

Myles Over a year ago

Then figure out a way to determine that, or make them all pass by reference would be my suggestion. Not much else you can do I'm afraid.

ymakux Over a year ago

Myles: what if I don't know amount of arguments in the array?

Myles Over a year ago

@ymakux ultimately you need an array of references. You'll be passing something so just create an array from whatever that something is.

ymakux Over a year ago

yes, right, seems call_user_func_array becomes useless in my case, i have to write spaghetti code instead of this switch(count($args)) { case 0: $class->{$method}(); break; case 1: }

Björn Tantau · Accepted Answer · 2013-08-19 09:15:12Z

7

A great workaround was posted on http://www.php.net/manual/de/function.call-user-func-array.php#91503

function executeHook($name, $type='hooks'){ 
    $args = func_get_args(); 
    array_shift($args); 
    array_shift($args); 
    //Rather stupid Hack for the call_user_func_array(); 
    $Args = array(); 
    foreach($args as $k => &$arg){ 
        $Args[$k] = &$arg; 
    } 
    //End Hack 
    $hooks = &$this->$type; 
    if(!isset($hooks[$name])) return false; 
    $hook = $hooks[$name]; 
    call_user_func_array($hook, $Args); 
}

The actual hack is surrounded by comments.

answered Aug 19, 2013 at 9:15

Björn Tantau

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3 Comments

Mangiucugna Over a year ago

thank you man, saved my life! this is definitely the correct answer

maryisdead Over a year ago

Spoke too soon … While this removes the error, it wouldn't let me manipulate the referenced variable inside the callable.

mvorisek Over a year ago

For PHP 5.6 and above declare the function with , &...$args and then call the hook as simple as $hook(...$args).

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