call_user_func
Call the callback given by the first parameter
Description
mixed call_user_func(callable $callback, mixed ...$args)
Parameters
-
callback
-
The callable to be called.
-
args
-
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 $a."\n";
// it is possible to use this instead
call_user_func_array('increment', array(&$a));
echo $a."\n";
// it is also possible to use a variable function
$increment = 'increment';
$increment($a);
echo $a."\n";
?>
The above example will output:
Warning: Parameter 1 to increment() expected to be a reference, value given in …
0
1
2
Return Values
Returns the return value of the callback.
Examples
Example #2 call_user_func example
<?php
function barber($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');
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:
Example #5 Using lambda function with call_user_func
<?php
call_user_func(function($arg) { print "[$arg]\n"; }, 'test');
?>
The above example will output:
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
- is_callable
- Variable functions
- ReflectionFunction::invoke
- ReflectionMethod::invoke