call_user_func

(PHP 4, PHP 5, PHP 7, PHP 8)

call_user_func把第一个参数作为回调函数调用

说明

call_user_func ( callable $callback , mixed $parameter = ? , mixed $... = ? ) : 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()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

Anonymous 17-Mar-2021 06:09
In this just for test writing to the doc
James at enfsolar dot com 11-Dec-2019 12:08
<?php

class MyClass{

    public function
hello($str)

    {

        echo
'hello ' . $str;

    }

}

$obj = new MyClass();

[
$obj, 'hello']('World'); // the array can be called as a function
luciano_closs at hotmail dot com 13-Dec-2018 11:42
Actually, as PHP 7.0, when you want to call a static method, you must call:

<?php

namespace Foobar;

class
Foo {
   static public
some() {
      echo
'Hello World!';
   }
}

call_user_func( array( __NAMESPACE__ . '\\Foo', 'some' ) );

?>

This will output:

Hello World!
slinstj at gmail dot com 09-May-2018 02:00
Updating "insta at citiesunlimited dot com"'s benchmarking for PHP 7.1.17 we have an INVERSION of results between using variables and call_user_func():

// RESULTS

Variable functions took 0.0020599365234375 seconds.
call_user_func took 0.00094509124755859 seconds.
eval took 0.024421215057373 seconds.

So, call_user_func() is now actually the way to go in PHP 7.1+.

<?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 />" );

?>
fab2s at marsatak dot org 02-Mar-2017 12:35
@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 12:18
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 28-Dec-2016 11:30
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 07-Jun-2016 09:29
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.
blakerenton09 at yahoo dot com 06-Jun-2011 04:45
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 05:50
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 10:38
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 08:49
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 04-Oct-2009 04:08
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 07:18
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 08:50
<?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 03-Nov-2007 10:26
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 05:31
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.
Typer85 at gmail dot com 12-Sep-2006 03:57
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.
rlansky at webroot dot com 14-Jul-2006 04:17
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 13-Apr-2006 03:41
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 12:15
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 01:42
>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";

?>
info at webseiteselberpflegen dot de 18-May-2005 01:00
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();
?>
24-Feb-2005 07:46
<?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 02:57
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 );
?>
arjini at mac dot com 29-Mar-2004 05:04
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 22-Jan-2004 03:21
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 08:49
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 11:53
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";
    }
}
?>
dougqh at hotmail dot com 07-Mar-2002 05:16
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 17-Jul-2001 04:31
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 :).