(PHP 4, PHP 5, PHP 7, PHP 8)
call_user_func — Call the callback given by the first parameter
Calls the callback given by the first parameter and passes
the remaining parameters as arguments.
callbackThe callable to be called.
argsZero or more parameters to be passed to the callback.
Note:
Note that the parameters for call_user_func() are not passed by reference.
Example #1 call_user_func() example and references
<?php
error_reporting(E_ALL);
function increment(&$var)
{
$var++;
}
$a = 0;
call_user_func('increment', $a);
echo $a."\n";
// it is possible to use this instead
call_user_func_array('increment', array(&$a));
echo $a."\n";
// it is also possible to use a variable function
$increment = 'increment';
$increment($a);
echo $a."\n";
?>The above example will output:
Warning: Parameter 1 to increment() expected to be a reference, value given in … 0 1 2
Returns the return value of the callback.
Example #2 call_user_func() example
<?php
function barber($type)
{
echo "You wanted a $type haircut, no problem\n";
}
call_user_func('barber', "mushroom");
call_user_func('barber', "shave");
?>The above example will output:
You wanted a mushroom haircut, no problem You wanted a shave haircut, no problem
Example #3 call_user_func() using namespace name
<?php
namespace Foobar;
class Foo {
static public function test() {
print "Hello world!\n";
}
}
call_user_func(__NAMESPACE__ .'\Foo::test');
call_user_func(array(__NAMESPACE__ .'\Foo', 'test'));
?>The above example will output:
Hello world! Hello world!
Example #4 Using a class method with call_user_func()
<?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');
$myobject = new myclass();
call_user_func(array($myobject, 'say_hello'));
?>The above example will output:
Hello! Hello! Hello!
Example #5 Using lambda function with call_user_func()
<?php
call_user_func(function($arg) { print "[$arg]\n"; }, 'test');
?>The above example will output:
[test]
Note:
Callbacks registered with functions such as call_user_func() and call_user_func_array() will not be called if there is an uncaught exception thrown in a previous callback.
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,
-- GregYou 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.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.<?php
class MyClass{
public function hello($str)
{
echo 'hello ' . $str;
}
}
$obj = new MyClass();
[$obj, 'hello']('World'); // the array can be called as a function