call_user

add a note User Contributed Notes

jaimz at vertigolabs dot org
28-Oct-2006 01:40


replay to bkfake-php at yahoo dot com's comment:



that's not passing by referance, your explicitly setting the value of $testy's member variable, infact, if you take the & out of your outsidefunc() it still works...

bkfake-php at yahoo dot com
27-Oct-2006 01:18


I have found a case where the parameters ARE passed by reference



class test

{

    function test()

    {

        $this->passme = '';

        call_user_func('outsidefunc',$this);

        // $this->passme is now 'not empty'

        // with 5.1.2

        // not so with php 4.3.10...

    }

}



function outsidefunc(&$testy)

{

     $testy->passme = 'not empty';

}

$test = new test();

echo 'passme = '.$test->passme;

Typer85 at gmail dot com
12-Sep-2006 06:57


I would just like to say at first that I prefer variable function calls over the use of this function.



However I found that at some times, the use of this function is needed in situtations where variable function calls can not be used. And in those same situations, the use of this function is also better than using eval.



The situation I ran into is this:



I wanted to call object methods dynamically from within the object but with arguments given for possible parameters that the method I will call requires.



The parameters themselves are dynamic, meaning I have no prior knowledge of how many their are, their values, or if they even exist.



Also because object methods are dynamic, meaning I have no prior knowledge which object method will actually be called, I can not simply use variable function calls, call the method and pass any parameters.



So what I simply do is call the object method with an array of parameters, something that, to the best of my knowledge, can not be done with variable function calls, since variable function calls, even though they themeselves are dynamic, passing parameters to them is not.

watchout at no dot spam dot please
29-Aug-2006 09:05


> This particular case will not work. The user functions can only be successfully called (as the documentation alludes to), with static calls to class functions.



actually it *does* work on PHP 5.0.2 (tested), and should also work on PHP 4.3.x (untested). Also the documentation does not state that only calls to static class methods are possible, but it says clearly that calls to OBJECT (thats dynamic) methods are possible: http://cz.php.net/manual/en/language.pseudo-types.php (see under type callback)

26-Jul-2006 03:18


Re: bostjan dot skufca at domenca dot com 's comment



"If you need to call object method from within the very same object (NOT CLASS!):

call_user_func(array(&$this, 'methodFoo'));"



This particular case will not work. The user functions can only be successfully called (as the documentation alludes to), with static calls to class functions.

rlansky at webroot dot com
15-Jul-2006 07:17


Based on the previous posts, it appears that using call_user_func can be serveral times slower than using variable substitution. I think these results are somewhat misleading.



I set up a similar test in which a static method of an object was called repeatedly in a loop. I got similar results to those seen; when calling the method using call_user_func the execution was twice that of calling the method directly. However, I then started adding some "meat" to the method in question. In my case, I found that what was constant was not the percentage change, but rather that there is a fixed cost to using call_user_func. 



In my case, this fixed cost was 2 microseconds per call. When executing a method that performs no operations, this is a large percentage of the execution time for that method. However, when using this on a method that actually performs some work, the 2 microsecond cost is almost impossible to measure.



It seems to me that if you want to use call_user_func to call a very fast executing method, and you need to do this thousands of times, then you may want to reconsider. However, if you are using this to call methods that are not executed thousands of times, the small fixed cost of using php call_user_func is probably not an issue.

Maresa
14-Apr-2006 06:41


I tested the same code that insta at citiesunlimited dot com pasted on the following machines:



www1 machine:

OS:  FreeBSD 5.2.1-RELEASE

CPU: 2 x Intel(R) Xeon(TM) CPU 2.66GHz (2657.82-MHz 686-class CPU) with Hyperthreading

MEM: 1073217536 (1023 MB)

PHP 5.1.2 (cli)

PHP 4.4.1 (Web)



www2 machine:

OS:  Linux version 2.6.14-gentoo-r5 Gentoo 3.4.3-r1, ssp-3.4.3-0, pie-8.7.7)

CPU: 2 x Dual Core AMD Opteron(tm) Processor 265 stepping 02 1808.357 MHz

MEM: 2060388k total

PHP 5.1.2 (cli)

PHP Version 4.4.0-pl1-gentoo (web)



dev machine:

OS:  Linux version 2.6.15-gentoo-r1 Gentoo 3.3.5.20050130-r1, ssp-3.3.5.20050130-1, pie-8.7.7.1

CPU: Intel(R) Pentium(R) 4 CPU 2.00GHz stepping 04

MEM: 516384k total,

PHP 4.4.0-pl1-gentoo (cli)

PHP Version 4.4.0-pl1-gentoo (web)



The result are as follows:



www1 - CLI

Variable functions took 0.012186050415 seconds.

call_user_func took 0.0300550460815 seconds.

eval took 0.17235994339 seconds.



www1 - Web

Variable functions took 0.017616 seconds. 

call_user_func took 0.034926 seconds. 

eval took 0.149618 seconds



www2 - CLI

Variable functions took 0.0065491199493408 seconds.

call_user_func took 0.019452095031738 seconds.

eval took 0.10734891891479 seconds.



www2 - Web

Variable functions took 0.01565 seconds. 

call_user_func took 0.02613 seconds. 

eval took 0.132258 seconds.



dev - CLI

Variable functions took 0.025176 seconds.

call_user_func took 0.047402 seconds.

eval took 0.168196 seconds.



dev - Web

Variable functions took 0.025465 seconds. 

call_user_func took 0.049713 seconds. 

eval took 0.20154 seconds.



On www1 - CLI, eval is about 14 times slower than calling function by using variable.

On www1 - Web, eval is about 8.5 times slower (hmm interesting. Perhaps PHP4 is faster calculating eval than PHP5)



On www2 - CLI, eval is about 16 times slower than calling function by using variable.

On www2 - Web, eval is about 8.5 times slower (about same result as www1)



On dev - CLI, eval is about 6.6 times slower than calling function by using variable.

On dev - Web, eval is about 8 times slower (about same result as www1)



On the dev machine, CLI and web version of PHP is the same. and their speed difference between calling function using variable or eval does not differ that much compare to PHP5 VS PHP5

insta at citiesunlimited dot com
07-Feb-2006 04:15


I benchmarked the comparison in speed between variable functions, call_user_func, and eval.  My results are below:



Variable functions took 0.125958204269 seconds.

call_user_func took 0.485446929932 seconds.

eval took 2.78526711464 seconds.



This was run on a Compaq Proliant server, 180MHz Pentium Pro 256MB RAM.  Code is as follows:



<?php



function fa () { return 1; }

function fb () { return 1; }

function fc () { return 1; }



$calla = 'fa';

$callb = 'fb';

$callc = 'fc';



$time = microtime( true );

for( $i = 5000; $i--; ) {

    $x = 0;

    $x += $calla();

    $x += $callb();

    $x += $callc();

    if( $x != 3 ) die( 'Bad numbers' );

}

echo( "Variable functions took " . (microtime( true ) - $time) . " seconds.<br />" );



$time = microtime( true );

for( $i = 5000; $i--; ) {

    $x = 0;

    $x += call_user_func('fa', '');

    $x += call_user_func('fb', '');

    $x += call_user_func('fc', '');

    if( $x != 3 ) die( 'Bad numbers' );

}

echo( "call_user_func took " . (microtime( true ) - $time) . " seconds.<br />" );



$time = microtime( true );

for( $i = 5000; $i--; ) {

    $x = 0;

    eval( '$x += ' . $calla . '();' );

    eval( '$x += ' . $callb . '();' );

    eval( '$x += ' . $callc . '();' );

    if( $x != 3 ) die( 'Bad numbers' );

}

echo( "eval took " . (microtime( true ) - $time) . " seconds.<br />" );



?>

Marco
05-Oct-2005 04:42


>phil at gettcomm dot com

>22-May-2002 04:51

>if you need to get a reference back from a method, you can work around 

>call_user_func()'s shortcomings like this:

>

Naaa! Having back a refererence is a real problem, but it can be solved by mean of eval(), instead of using call_user_func: 



<code>

  class Node {

    var $name;

    var $child;

    function Node ( $name ) { $this->name = $name; }

    function &getChild () { return $this->child; }

  }

  $p = new Node ( 'Father' );

  $c = new Node ( 'Child' );

  $p->child = &$c;  



  eval ( "\\$cref = &\\$p->getChild ();" );

  $cref->name = 'Another Child';



  // Prints out 'Another Child'

  echo "****** After eval c = " . $c->name . "\\n\\n";



</code>

php at REMOVEMEkennel17 dot co dot uk
09-Aug-2005 11:46


re comment by mw at lanfear dot com



I am using PHP 4.3.2 and that technique works fine here as well.

mw at lanfear dot com
27-Jul-2005 04:49


This function is actually quite useful for calling static methods on classes, which you CANNOT call as:



$v1 = 'MyClass';

$m1 = 'method';

$v1::$m1();           // syntax error -- not permitted.



The following, however, DOES work quite well, and is hopefully slightly faster than eval() ...



$ar = array($v1, $m1);



call_user_func($ar);    // works teh awes0me!!1!



[I am, however, presuming PHP5 here ...]

zeisss at web dot de
23-Jun-2005 10:34


------------------------------------------- 

Hey



I'm struggling to think of a practical use for this function that can't be duplicated with variable functions. The only use I can think of is when calling variable functions when your variable need modification:

--------------------------------------------



I tried to call nl2br() with variable functions. Didn't work. But call_user_func worked. Dunno why, just for info.

FRANK at ETHISOFT dot NL
08-Jun-2005 07:36


You should avoid this function and use variable function calls instead!

The main reason for this is the fact that you will generate twice as many function calls as actually needed. 

Thus, your server will encounter twice the load of function calls.



You people should not want this!

@ your service!

info at webseiteselberpflegen dot de
19-May-2005 04:00


It seems like call_user_func() can not be used to create Objects via the new Command.



The Following example dosen't work:

<?

  include_once(class_".$type.".php");

  $object = new call_user_func ('bdv_'.$type);

?>



But this works:

<?

    include_once(class_".$type.".php");

    $constr = 'bdv_'.$type;

    $object = new $constr();

?>

d at safetypub dot org
16-Mar-2005 12:43


callbacks, this par excellence, goes with set error handler, everywhere you'ren't sure of extensio de intensionibus (animis alii).



<?php



$checkMe = null;

$detail = array();

set_error_handler("imErrant");



array_shift($argv);

if ($argc == 1){

        call_user_func(strtolower($argv[0]));

} else if($argc == 2){

        call_user_func(strtolower($argv[0]), $argv[1]);

} 

else

        call_user_func_array(strtolower($argv[0]),array_shift($argv));



if($checkMe)var_export($detail);



function imErrant($no, $str, $file, $line)

{

    global $checkMe, $detail;

    $checkMe = $no;

    $detail = array($str, $file, $line);

}

?>

25-Feb-2005 11:46


<?php

/*

    A very simple event handler dispose and change the latest one I did

*/



class Duke

{

//public:

    var $m_pRaiser;

    var $m_strRaiserFun;

    var $m_objArgs;

//public:

    function Duke(  $pRaiser,

            $strRaiserFun,

            $objArgs )

    {

        $this ->m_pRaiser      = $pRaiser;

        $this ->m_strRaiserFun = $strRaiserFun;

        $this ->m_objArgs      = $objArgs;



    }//end of constructor



}//end of class Duke



class A

{

//protected:

    function OnEventHandler( $sender, $args )//virtual

    {

        $sender ->SayHello();

    }//end of OnEventHandler( $sender, $args )

 

//public:

    function OnEvent( $pDuke = null )

    {        

        if( $pDuke == null )

        {

            call_user_func( array( &$this, "OnEventHandler" ), $this, null );

            return;

        }



        call_user_func( array( $pDuke ->m_pRaiser, $pDuke ->m_strRaiserFun ), $pDuke ->m_pRaiser, $pDuke ->m_objArgs );



    }//end of  OnEvent( $pDuke )



    function SayHello()//virtual

    {

        echo "A::SayHello" . "<br>";

    }//end of SayHello() 



}//end of class A



class B extends A

{

//public:

    function SayHello()//override

    {

        echo "B::SayHello" . "<br>";

    }//end of SayHello()



}//end of class B



//////////////////////////////////////////////////////////////////////

//Main import to test

//

$a = &new A();

$b = &new B();



$pDuke = &new Duke( $b, "OnEventHandler", null );



$b ->OnEvent();

$b ->OnEvent( $pDuke );

?>

zxy at estec-jp dot com
24-Feb-2005 06:57


A simple event handler dispose released by useful callback in PHP 4.x



<?php

class Duke

{

//public:

    var $m_pRaiser;

    var $m_strRaiserFun;

    var $m_objArgs;

//public:

    function Duke(  $pRaiser,

            $strRaiserFun,

            $objArgs )

    {

        $this ->m_pRaiser      = $pRaiser;

        $this ->m_strRaiserFun = $strRaiserFun;

        $this ->m_objArgs      = $objArgs;



    }//end of constructor



}//end of class Duke



class A

{

//protected:

    function OnEventHandler( $sender, $args )//virtual

    {

        $sender ->SayHello();

    }//end of OnEventHandler( $sender, $args )

 

//public:

    function OnEvent( $pDuke )

    {

        call_user_func( array( $pDuke ->m_pRaiser, $pDuke ->m_strRaiserFun ), $pDuke ->m_pRaiser, $pDuke ->m_objArgs );

    }//end of  OnEvent( $pDuke )



    function SayHello()//virtual

    {

        echo "A::SayHello" . "<br>";

    }//end of SayHello() 



}//end of class A



class B extends A

{

//public:

    function SayHello()//override

    {

        echo "B::SayHello" . "<br>";

    }//end of SayHello()



}//end of class B



///////////////////////////////////////////////////////////

//Main import to test

//

$a = &new A();

$b = &new B();



$pDuke = &new Duke( $b, "SayHello", null );

$b ->OnEvent( $pDuke );

?>

rob at PLEASEDONT dot digital-crocus dot SPAMME dot com
18-Feb-2005 10:16


Hey



I'm struggling to think of a practical use for this function that can't be duplicated with variable functions. The only use I can think of is when calling variable functions when your variable need modification:



<?php



function hey1 { echo "hey1"; }

function hey2 { echo "hey2"; }

function hey3 { echo "hey3"; }



for ($n = 1; $n <= 3; $n++) {



  // variable variables:



  $func = "hey$n";

  $$func();



  // call_user_func():



  call_user_func("hey$n");

}



?>



call_user_func() is one less line, however I would always use variable variables for readability. Are there any more practical uses I'm overlooking?

bostjan dot skufca at domenca dot com
15-Dec-2004 04:33


This is the CORRECTED VERSION of previous note. After playing a while I realised that objects are not passed by reference implicitly, you have to do it on your own, so:



call_user_func(array($objectBar, 'methodFoo')); // case sensitive



first duplicates object $objectBar (internally) and only then calls it's methodFoo. This kind of use is discouraged as it may result in "unpredicted behaviour".



Correct version is here.

call_user_func(array(&$objectBar, 'methodFoo')); // case sensitive

(note the reference operator).



--- and the corrected note is here ---



I couldn't find any simple list of available callback variations, so I made one. It is tested on PHP 4.3.9 only.



If you need to call ordinary function:

call_user_func('funcFoo');



If you need to call CLASS method (NOT object):

call_user_func(array('classBar', 'methodFoo')); // case insensitive



If you need to call OBJECT method:

call_user_func(array(&$objectBar, 'methodFoo')); // case sensitive



If you need to call method of object of object:

call_user_func(array(&$objectBar->objectTor, 'methodFoo')); // case sensitive



If you need to call object method from within the very same object (NOT CLASS!):

call_user_func(array(&$this, 'methodFoo'));

07-Oct-2004 03:23


If you are trying to instantiate an object from a class whose name is dynamic, you WILL NOT be able to do this with call_user_func() and I do not suggest that you do it with eval(). The way to do it is actually much simpler than i thought. As far as i know this works in PHP 4 and 5:



<?PHP

class foo {

 var $boo;

    function foo( $someVal ) {

     $this->boo = $someVal;

    }

}



$ClassToUse = "foo";

$bar = new $ClassToUse('test');

echo $bar->boo;

?>

arjini at mac dot com
30-Mar-2004 09:04


Some of the wierder examples below confused me, and made me think that the following would work (but it does!).



<?



class barber{

    function shop($one,$two,$three,$four='quartet'){

        echo $one.','.$two.','.$three.','.$four;

    }

}



$bsq = new barber;

call_user_func(array(&$bsq,'shop'),'one','two','three');



/* Output = one,two,three,quartet */



class bigBarber{

    var $quartet;

    function bigBarber(){

        $this->quartet = 'four';

    }

    function shop($one,$two,$three,$five='quintet'){

        echo $one.','.$two.','.$three.','.$this->quartet.','.$five;

    }

}



$bbsq = new bigBarber();

call_user_func(array(&$bbsq,'shop'),'one','two','three');



/* Output = one,two,three,four,quintet */



?>

Kris Koskelin
23-Jan-2004 07:21


I was trying to use this function to call a method of an already-instantiated object.  I needed to do this with the object itself, not simply call the class' method.



To accomplish this, I really avoided this particular function altogether like this:

<?

if ( method_exists($my_obj, $action) ){

     return $my_obj->{$action}();

}

?>

I hope someone else finds this useful.  Note that doing this allows you to pass params to the function more-or-less in the same way you would to any other class method.

Michele.Manzato at verona.miz.it
29-Sep-2003 11:49


With overload()ed classes call_user_func_* calls real class methods only. If the method does not exist then PHP does not try with the "__call()" magic method (at least until PHP 4.3.3). See this:



<?php

class A 

{

    function A() {}

    

    function __call($method, $args, &$ret) {

        echo "__call(): You called '{$method}()'<br>\n";

        return true;

    }

    

    function regular() {

        echo "You called 'regular()'<br>\n";

    }        

};

overload("A");



$a = new A;



$a->regular();                          // Works, calls regular()

call_user_func(array(&$a, "regular"));  // Works, calls regular()



$a->hello();                            // Works, calls __call()

call_user_func(array(&$a, "hello"));    // Does NOT work!

?>

Carl
29-Jul-2003 02:53


I had a problem where I wanted to parameterize a callback. The end called was in an external class, but I needed to save some state for the callback that didn't make sense to keep in the original object, as it might change from call to call...





<?php


class foo 


{


    function foo()


    {


        $str = "Hello There";





        $str2 = "Carl";





        $that =& new holder($str);





        call_user_func(array(&$that, 'callback'), $str2);


    }


}





class holder


{


    function holder($aParam)


    {


        $this->param = $aParam;


    }





    function callback($aStr)


    {


        echo "A=$this->param, B=$aStr\n";


    }


}


?>

matt at tasonline dot com
24-Nov-2002 04:24


On PHP 4.2.3 (not sure about older releases) you can send objects by reference by sending the reference from call_user_func()





<?php


function myFunction(@$obj)


{


   $obj->doThis('hello');


   return 0;


}





$myObj = new CObject();





call_user_func('myFunction', @$myObj);


?>

phil at gettcomm dot com
22-May-2002 10:51


if you need to get a reference back from a method, you can work around call_user_func()'s shortcomings like this:



<?



$globalObj;



class tClass

{

    function &instance()

    {

        global $globalObj;

        if(!is_object($globalObj))

        {

            $globalObj = new tClass();

        }

        return $globalObj;

    }

}



$classname = "tClass";

# calling the function this way won't 

# return a reference.

$test = &call_user_func(array($classname,"instance"));

# but if we call it again with the instance

# that we just got, it'll be the right

# one

$test = &$test->instance();

# so test is now a reference to $globalObj, just like it should be



# let's verify it:

$test->blah=1;



echo "<pre>";

print_r($test)."\n";

print_r($globalObj);

echo "</pre>";

# there, now it behaves just like you'd expect



?>

teleware at mind dot net
09-Apr-2002 04:34


I ran into some quirky behavior using call_user_func with an object.  The function parseAction() below lets me call any of my object's methods by passing the name of the method into a page (e.g. http://xyz.com/page.php?action=login).





<?php


class MyClass {





    function parseAction($actionKey)


    {


        global $METarget;





        if(method_exists($this,$actionKey))


        {


            call_user_func(array(&$this,$actionKey));


            return;


        }


        else


        {


            exit("Unknown action keyword: $actionKey");


        }


    }





    ... 


    // other methods


    ...


}


?>





I found that my member variables weren't always being updated correctly.  The numberic values were preserved but the string variables retained their old value.  The solution was to put the reference operator '&' in front of the object's variable.  In this case it's $this because I'm calling it from within the object but this was also true when calling parseAction from an instanciated object e.g. call_user_func(array(&$myObject,$actionKey))

dougqh at hotmail dot com
08-Mar-2002 09:16


The previous note I posted had an error in the source code.  That has been corrected in this note.



Note, that returning by reference does not work properly when the function

is called using call_user_func.



This example illustrates the problem...



$globalVar = 0;



function &staticFunction()

{

   global $globalVar;

   

   return $globalVar;

}



$result =& call_user_func( "staticFunction" );



$result = 3;



print "result:" . $result . "<br/>\n";

print "globalVar: " . $globalVar . "<br/>\n";



$result2 =& staticFunction();



$result2 = 3;



print "result2: " . $result2 . "<br/>\n";

print "globalVar: " . $globalVar . "<br/>\n";



The above code results in the following output ...

Note that $result is not a reference to $globalVar.



result:0

globalVar: 0

result2: 3

globalVar: 3



Also, the use of call_user_method is now deprecated in favor of passing

array( &$object, $method ) as the function to call_user_func.  This is

reported when error reporting is set to E_ALL in the latest versions of

PHP.

danyloco at yahoo dot com
18-Jul-2001 07:31


I was trying to call multiple functions within a class, and after a brain frying experience this is what came out... hope it helps:





<?php


class Foo {


 function hey1($id){echo "In hey1";}


 function hey2($id){echo "In hey2";}


 #... and so forth ...


 function runtest($id) {


   #the fun part :)


   for($i=1; $i<=2; $i++) {


     $fp = "hey".$i;


     $this->$fp($id);


}


}


}


?>





It worked like a charm :).

dayiogluNOSPAM at metu dot edu dot tr dot NOSPAM
12-Mar-2001 07:03


Happily call_user_func can now call


methods of some existing objects; added


to the CVS Fri Mar  9 18:09:26 2001 EDT.





Below is an example:





<?php





class provider {


  function myfunction($x) {


    echo "burak was at $x\n";


  }


}





class dispatcher {


  function process($p2,$p3) {


    call_user_func($p2, $p3);


  }


}





function independent()


{


  echo "just a test";


}





$x= new provider();


$y= new dispatcher();





$y->process(array($x,'myfunction'),"conference");


$y->process(independent,"");





?>

ceco at noxis dot net
29-Nov-2000 01:01


I find it easier in a lot of cases to use something like that


<?


function test($p1){


  echo $p1."<br>";


  return $p1/2; // just an example


}





$func = "test";


echo $func(6);


?>

tetherow at nol dot org
30-Aug-2000 04:39


Trying to call a class method with call_user_function? call_user_method doesn't really work since you need an object to pass to the call.  You can get around it by creating a 'place holder' instance and call_user_method.

andreyhristov at yahoo dot com
22-Aug-2000 09:09


Let say we construct somehow the name of the function. In some cases we can use nested  'switch'  but the alternative is to to use for and parse a string to construct  the  function  name, after than  we also can construct and the 


parameter(s) for it. It  is like using of eval. I use it in  one of my projects to construct a name of nested array like


$ar['1999'['july']['29']['19'] , etc. the problem is in that I'm parsing a string to construct the name. If I've {1:2:3}  the array name  will be $ar['1']['2']['3'] but if i've


{1:2:3:4:5} it will  be $ar['1']['2']['3']['4']['5'].  Eval is the only way (very hard because of characters escaping is needed)  to do it. So this function is of the type of EVAL().


USE IT wherever your script is  'self-modified';

add a note

call_user_func

Description