call_user_func
(PHP 4, PHP 5, PHP 7)
call_user_func — Call the callback given by the first parameter
Description
Calls the callback given by the first parameter and passes
the remaining parameters as arguments.
Parameters
-
callback -
The callable to be called.
-
... -
Zero 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 $a."\n";
// You can use this instead
call_user_func_array('increment', array(&$a));
echo $a."\n";
?>The above example will output:
Warning: Parameter 1 to increment() expected to be a reference, value given in … 0 1
Changelog
| Version | Description |
|---|---|
| 5.3.0 |
The interpretation of object oriented keywords like parent
and self has changed. Previously, calling them using the
double colon syntax would emit an E_STRICT warning because
they were interpreted as static.
|
| 5.3.0 |
If the called function expects a parameter to be passed by reference, an
E_WARNING is now issued.
|
Examples
Example #2 call_user_func() example
<?php
function barber($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'); // As of PHP 5.3.0
call_user_func(array(__NAMESPACE__ .'\Foo', 'test')); // As of PHP 5.3.0
?>
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'); // As of 5.2.3
$myobject = new myclass();
call_user_func(array($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'); /* As of PHP 5.3.0 */
?>
The above example will output:
[test]
Notes
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.
See Also
- call_user_func_array() - Call a callback with an array of parameters
- is_callable() - Verify that the contents of a variable can be called as a function
- information about the callback type
- ReflectionFunction::invoke() - Invokes function
- ReflectionMethod::invoke() - Invoke
English translation
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Document created the 30/01/2003, last modified the 26/10/2018
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References
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