call_user_func

(PHP 4, PHP 5, PHP 7)

call_user_func — 把第一个参数作为回调函数调用

说明

mixed call_user_func ( callable $callback [, mixed $parameter [, mixed $... ]] )

第一个参数 callback 是被调用的回调函数，其余参数是回调函数的参数。

参数

callback

将被调用的回调函数（callable）。

parameter

0个或以上的参数，被传入回调函数。

Note:

请注意，传入call_user_func()的参数不能为引用传递。

Example #1 call_user_func() 的参考例子

<?php
error_reporting(E_ALL);
function increment(&$var)
{
    $var++;
}

$a = 0;
call_user_func('increment', $a);
echo $a."\n";

call_user_func_array('increment', array(&$a)); // You can use this instead before PHP 5.3
echo $a."\n";
?>

以上例程会输出：

0
1

返回值

返回回调函数的返回值。

更新日志

版本 说明
5.3.0 对面向对象里面的关键字的解析有所增强。在此之前，使用两个冒号来连接一个类和里面的一个方法，把它作为参数来作为回调函数的话，将会发出一个E_STRICT的警告，因为这个传入的参数被视为静态方法。

范例

Example #2 call_user_func() 的例子

<?php
function barber($type)
{
    echo "You wanted a $type haircut, no problem\n";
}
call_user_func('barber', "mushroom");
call_user_func('barber', "shave");
?>

以上例程会输出：

You wanted a mushroom haircut, no problem
You wanted a shave haircut, no problem

Example #3 call_user_func() 命名空间的使用

<?php

namespace Foobar;

class Foo {
    static public function test() {
        print "Hello world!\n";
    }
}

call_user_func(__NAMESPACE__ .'\Foo::test'); // As of PHP 5.3.0
call_user_func(array(__NAMESPACE__ .'\Foo', 'test')); // As of PHP 5.3.0

?>

以上例程会输出：

Hello world!
Hello world!

Example #4 用call_user_func()来调用一个类里面的方法

<?php

class myclass {
    static function say_hello()
    {
        echo "Hello!\n";
    }
}

$classname = "myclass";

call_user_func(array($classname, 'say_hello'));
call_user_func($classname .'::say_hello'); // As of 5.2.3

$myobject = new myclass();

call_user_func(array($myobject, 'say_hello'));

?>

以上例程会输出：

Hello!
Hello!
Hello!

Example #5 把完整的函数作为回调传入call_user_func()

<?php
call_user_func(function($arg) { print "[$arg]\n"; }, 'test'); /* As of PHP 5.3.0 */
?>

以上例程会输出：

[test]

注释

Note:

在函数中注册有多个回调内容时(如使用 call_user_func() 与 call_user_func_array())，如在前一个回调中有未捕获的异常，其后的将不再被调用。

参见

User Contributed Notes

fab2s at marsatak dot org 02-Mar-2017 09:35
@insta at citiesunlimited dot com & @Maresa

call_user_func() alleged slowness is quite over estimated when it comes to real use cases. we are talking about loosing fraction of a second every million calls, which by the way would take less than half a sec to execute in the worst case.

I don't know of many processes that would actually suffer from this kind of overhead.

Iterations: 100 000
Averaged over: 10
PHP 5.6.30 (cli) (built: Jan 18 2017 19:47:28)
Overall Average
+------------------------+----------+-----------+--------+
| Invocation             | Time (s) | Delta (s) | %      |
+------------------------+----------+-----------+--------+
| directFunction         | 0.0089   | -0.0211   | -70.19 |
| directStatic           | 0.0098   | -0.0202   | -67.39 |
| directLambda           | 0.0109   | -0.0191   | -63.52 |
| directInstance         | 0.0116   | -0.0184   | -61.31 |
| directClosure          | 0.0150   | -0.0150   | -50.15 |
| Invoke                 | 0.0282   | -0.0018   | -6.13  |
| call_user_func         | 0.0300   |           |        |
| ClosureFactory         | 0.0316   | +0.0016   | +5.20  |
| assignedClosureFactory | 0.0328   | +0.0028   | +9.28  |
| call_user_func_array   | 0.0399   | +0.0099   | +33.02 |
| InvokeCallUserFunc     | 0.0418   | +0.0118   | +39.17 |
| directImplementation   | 0.0475   | +0.0175   | +58.28 |
+------------------------+----------+-----------+--------+

Iterations: 100 000
Averaged over: 10
PHP 7.1.2 (cli) (built: Feb 14 2017 21:24:45)
Overall Average
+------------------------+----------+-----------+--------+
| Invocation             | Time (s) | Delta (s) | %      |
+------------------------+----------+-----------+--------+
| directFunction         | 0.0043   | -0.0096   | -68.92 |
| directStatic           | 0.0050   | -0.0089   | -64.04 |
| directInstance         | 0.0058   | -0.0081   | -58.22 |
| directLambda           | 0.0063   | -0.0075   | -54.44 |
| directClosure          | 0.0081   | -0.0058   | -41.57 |
| call_user_func         | 0.0139   |           |        |
| call_user_func_array   | 0.0147   | +0.0008   | +5.84  |
| Invoke                 | 0.0187   | +0.0048   | +34.61 |
| ClosureFactory         | 0.0207   | +0.0069   | +49.43 |
| assignedClosureFactory | 0.0219   | +0.0080   | +57.75 |
| directImplementation   | 0.0232   | +0.0094   | +67.53 |
| InvokeCallUserFunc     | 0.0264   | +0.0126   | +90.67 |
+------------------------+----------+-----------+--------+

If you want more details : https://github.com/fab2s/call_user_func
fab2s at marsatak dot org 02-Mar-2017 09:18
The "Example #1 call_user_func() example and references" has become misleading since it will throw an exception starting from at least php 5.6.30:
<?php
//  Parameter 1 to increment() expected to be a reference, value given
?>

The crash occurs when call_user_func() is called as it does not provide increment() with a reference.

Also note that :

<?php
call_user_func('increment', &$a);
?>

will also  throw an exception :
<?php
// Call-time pass-by-reference has been removed
?>
developer at nabtron dot com 29-Dec-2016 08:30
We can achieve the same dynamically without call_user_func like this

<?php

class myclass {
    public function say_hello()
    {
        echo "Hello!\n";
    }
}

$classname = "myclass";

$myobject = new myclass();
$var = "say_hello";

(new myclass)->{$var}();
call_user_func(array(new myclass(), $var));
jcastro at eftec dot cl 08-Jun-2016 06:29
Lets say that $a1 is an object and fn is a function then:

echo $a1->fn('hello world');
echo $a1->{"fn"}('hello world');
echo call_user_func(array($a1, 'fn'),'hello world');

Are three valid ways to do the same.
Jordan LeDoux 06-Aug-2015 06:24
I re-ran the test insta outlined 9 years ago to see how things had changed.

Variable functions took 0.014201879501343 seconds.
call_user_func took 0.044676065444946 seconds.
eval took 0.17955899238586 seconds.

As expected, eval() is slowes by a wide margin, and variable functions are fastest. However, 9 years ago there weren't closures, and so I added them to the test for comparison.

closures took 0.012146949768066 seconds.

As you can see, closures ended up being the fastest, but all of these have experienced improvements. I also increased the number of loops per test to 50,000 from 5,000. This was tested with PHP 5.5.9 on Ubuntu LTS.

The original test code was:

<?php

function fa () { return 1; }
function fb () { return 1; }
function fc () { return 1; }

$calla = 'fa';
$callb = 'fb';
$callc = 'fc';

$time = microtime( true );
for( $i = 50000; $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 = 50000; $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 = 50000; $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 />" );

?>

Here is the closures addition.

<?php

$funa = function() { return 1; };
$funb = function() { return 1; };
$func = function() { return 1; };

$time = microtime( true );
for ($i = 50000; $i--; ) {
    $x = 0;
    $x += $funa();
    $x += $funb();
    $x += $func();
    if( $x != 3 ) die( 'Bad numbers' );
}
echo( "closures took " . (microtime( true ) - $time) . " seconds.<br />" );

?>
dexen dot devries at gmail dot com 04-Nov-2011 02:00
In PHP v5.2, you /can/ use call_user_func(array($this, 'parent::SOME_FUNCTION')).

If you don't have custom __autoload() function, you are good to go.

If you do have custom __autoload(), you need to make it `parent' aware. Something like:

<?php
function __autoload($classname) {
  if ($classname === 'parent')
    return;
  else
    //((load class definition))
}
?>

Rationale: PHP 5.2 surprisingly tries to autoload a class named `parent'. However, if you don't do anything in __autoload() for the `parent' class, it'll work just fine.
blakerenton09 at yahoo dot com 06-Jun-2011 01:45
call_user_func may also be used to call a closure or anonymous function that has been passed into a user-defined function.

<?php
function Benchmark()
{
    foreach(func_get_args() as $function)
    {       
        $st = microtime(true);
        call_user_func($function);
        $et = microtime(true);
        echo sprintf("Time: %f", $et - $st) . '<br />';
    }
}

Benchmark(function()
{
    for ( $i = 0; $i <= 10000; $i++ )
    { }
},
function()
{
    $i = 0;
    while ( $i <= 10000 )
    {
        $i++;
    }
});
?>

Returns:
Time: 0.001652
Time: 0.001458
romainbessuges at gmail dot com 09-May-2011 02:50
I made a wrapper for call_user_func_array which is really simple and convenient. It takes advantage of the __invoke() magic method :

<?php
class Func {
   
    public static function fromFunction($name){
        return new Func($name);
    }
   
    public static function fromClassMethod($class, $name){
        return new Func(array($class, $name));
    }
   
    public static function fromObjectMethod($object, $name){
        return new Func(array($object, $name));       
    }

    public $function;

    public function  __construct($function) {
        $this->function = $function;
    }

    public function __invoke(){
        return call_user_func_array($this->function, func_get_args());
    }
}
?>

Example :

<?php
$func = Func::fromObjectMethod($myArrayObject, "offsetGet");

echo $func(3);
?>
gskluzacek dot nospam at gmail dot com 11-Sep-2010 07:38
if you simply want to dynamically call a method on an object it is not necessary to use call_user_function but instead you can do the following:

<?php

$method_name = "AMethodName";

$obj = new ClassName();

$obj->{$method_name}();

?>

I've used the above so I know it works.

Regards,
-- Greg
moisadoru at gmail dot com 13-May-2010 05:49
Actually, when calling a static method of some class, the params are sent by reference:
<?php
class Foo {
    private $x = 0;
    public function getX(){
        return $this->x;
    }
    public function setX($val){
        $this->x = $val;
    }
}

class Bar {
    static function incStatic(Foo $f){
        $f->setX($f->getX()+1);
        global $foo;
        if($f === $foo) echo '<span style="color: blue">' . __METHOD__ . '() objects are equal</span><br />';
        else  echo '<span style="color: red">' . __METHOD__ . '() objects are not equal</span><br />';
    }
    public function incNonStatic(Foo $f){
        $f->setX($f->getX()+1);
        if($f === $foo) echo '<span style="color: blue">' . __METHOD__ . '() objects are equal</span><br />';
        else  echo '<span style="color: red">' . __METHOD__ . '() objects are not equal</span><br />';
    }
}

function inc(Foo $f){
    $f->setX($f->getX()+1);
    if($f === $foo) echo '<span style="color: blue">' . __FUNCTION__ . '() objects are equal</span><br />';
    else  echo '<span style="color: red">' . __FUNCTION__ . '() objects are not equal</span><br />';
}

$foo = new Foo;
$bar = new Bar;

call_user_func('inc', $foo);
call_user_func('Bar::incStatic', $foo);
call_user_func(array($bar, 'incNonStatic'), $foo);
?>

The results on PHP 5.2.6 (macosx 10.5):

inc() objects are not equal
Bar::incStatic() objects are equal
Bar::incNonStatic() objects are not equal

Hope it helps sombody.
Nitrogen 05-Oct-2009 01:08
A good use for call_user_func(); is for recursive functions.
If you're distributing code, you will often come across users who will rename functions and break the code..
Use this: call_user_func(__FUNCTION__, ... ); inside a function to call itself with whatever parameters you want.

<?php
// example, an extremely simplified factorial calculator..
// it's quite obvious when someone renames the function, it'll spit out an error because it wants to call itself.
function Factorial($i=1) {
  return($i==1?1:$i*Factorial($i-1));
}

// you can give this function whatever name you want, it'll always work, of course if you initially call it using the name you gave it.
function qwertyuiop($i=1) {
  return($i==1?1:$i*call_user_func(__FUNCTION__,$i-1));
}
?>

Just that I didn't see any reference to recursive functions when user_call_func(); really helps.
edgar dot klerks at gmail dot com 17-Mar-2009 04:18
An entirely OO solution to add dynamicly methods to classes, I used in a project:
<?php
class ProductPart {

        protected $data;
        protected $plugins = array();
        function __construct($data){

                $this->data = $data;

        }
        public function register(ProductPlugin $plugin){

                if(!in_array($plugin, $this->plugins)){

                        $this->plugins[$plugin->toString()] = $plugin;
                } else {
                        throw new Exception('Function allready defined');
                }
        }
        public function unregister(ProductPlugin $plugin){
                if(isset($this->plugins[$plugin->toString()])){
                        unset($this->plugins[$plugin->toString()]);
                } else {
                        throw new Exception('No such function');
                }

        }

        protected function __call($method, $args) {
              if(isset($this->plugins[$method])){
                array_unshift(&$args, $this->data);
                array_unshift(&$args, $this);
                return $this->plugins[$method]->run($args[0], $args[1], $args[2]);

              } else {
                throw new Exception('No such function');
              }
        }
} ?>

I simplified the class somewhat for clearity.

With this class, you can dynamicly add and remove classes by calling register or unregister. Register will store the object in an associative array by calling toString (as defined by ProductPlugin) and saving the method under the returned string in the array. (In this case the name of the method the class adds.)

When a method is called, which isn't standard in the object, _call will lookup the called method in the array. If found, __call run the method of the plugin with the provided arguments. I restricted the user provided argument to 1, because I want to force the user to use associative arrays.

Because I chose an array to store my classes, removing a function is quite simple. However the unregister function isn't optimal, I better pass a string instead of a plugin object. I didn't test it yet on performance.

The ProductPlugin class:

<?php

abstract class ProductPlugin {
        protected $name = null;
        abstract public function run($obj, $data, $args);
        public function __construct($data = null) {

                if($this->name === null){
                        throw new Exception('Name must be defined');
                }
                $this->init($data);
        }
        protected function init($data){

        }
        public function toString(){
                return $this->name;
        }
}

?>

And at last some demonstration code:

<?php
$bla = new ProductPart(array('HelloWorld' => 'Hello world'));
$hello = new helloPlugin();
$bla->register($hello);
$bla->HelloWorld();
$bla->unregister($hello);
$bla->HelloWorld();

?>
dead,screamer@seznam,cz 21-Dec-2008 05:50
<?php call_user_func()?> and <?php call_user_func_array()?> hide some errors (notices, warnings and maybe errors), even if is display_errors turned on and error_Reporting is set to E_ALL|E_STRICT
Maxdamantus 04-Nov-2007 07:26
Note that the parser can interpret variables in function syntax, which means you can pass all variables normally (eg: reference).

<?php
function myfunction($string, &$int){
    echo $string."\n";
    $int++;
}
$function_name = "myfunction";
$x = 1336;
$function_name("Hello World", $x);
echo $x;
?>
---
Hello World
1337
Knightnet 07-Sep-2007 02:31
You don't need to use this function to call a variable class function. Instead you can do the following:

$this->{$fnname}();

The example works in PHP 5 from within the class. It is the {} that do the trick.

Regards,
Julian.
lsblsb at gmx dot de 29-Jun-2007 01:55
referring to Mr.KTO (and Bug #24931):
[system: PHP 5.2.0-8] - _doesnt_ pass by reference, at least when using the old syntax with the '&'.

when you pass your object by reference using call_user_func, any changes made on that object within the called function wont effect your "original" object.

you should use mixed call_user_func_array ( callback $function, array $param_arr ) instead or eval() (slower).
Mr.KTO 14-Jun-2007 04:39
To send an object to your function by link, using call_user_func it's not enough (in php4) to define func(&$obj) { ... }

You need: call_user_func("callback", &$myobj)

(in php5 objects are sending by link as default)
jaimz at vertigolabs dot org 27-Oct-2006 07:40
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 26-Oct-2006 07:18
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 12:57
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 03:05
> 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)
rlansky at webroot dot com 15-Jul-2006 01:17
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 12:41
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 06-Feb-2006 09:15
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 10:42
>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 reference is a real problem, but it can be solved by mean of eval(), instead of using call_user_func:

<?php
  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";

?>
php at REMOVEMEkennel17 dot co dot uk 09-Aug-2005 05:46
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 26-Jul-2005 10:49
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 ...]
info at webseiteselberpflegen dot de 18-May-2005 10:00
It seems like call_user_func() can not be used to create Objects via the new Command.

The Following example dosen't work:

<?php
  include_once(class_".$type.".php");
  $object = new call_user_func ('bdv_'.$type);
?>

But this works:

<?php
    include_once(class_".$type.".php");
    $constr = 'bdv_'.$type;
    $object = new $constr();
?>
d at safetypub dot org 15-Mar-2005 05:43
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 04:46
<?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 11:57
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 );
?>
07-Oct-2004 09:23
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 02:04
Some of the wierder examples below confused me, and made me think that the following would work (but it does!).

<?php

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 12:21
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:

<?php
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 05:49
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 28-Jul-2003 08:53
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 23-Nov-2002 09:24
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 04:51
if you need to get a reference back from a method, you can work around call_user_func()'s shortcomings like this:

<?php

$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

?>
dougqh at hotmail dot com 08-Mar-2002 02:16
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...

<?php
$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 01:31
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 :).
andreyhristov at yahoo dot com 22-Aug-2000 03:09
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';