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 $callback, mixed ...$args): 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）。

args

0个或以上的参数，被传入回调函数。

注意:

请注意，传入call_user_func()的参数不能为引用传递。

示例 #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";

// 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";
?>

以上示例会输出：

Warning: Parameter 1 to increment() expected to be a reference, value given in …
0
1
2

返回值

返回回调函数的返回值。

示例

示例 #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");
?>

以上示例会输出：

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

示例 #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');
call_user_func(array(__NAMESPACE__ .'\Foo', 'test'));

?>

以上示例会输出：

Hello world!
Hello world!

示例 #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');

$myobject = new myclass();

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

?>

以上示例会输出：

Hello!
Hello!
Hello!

示例 #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');
?>

以上示例会输出：

[test]

注释

注意:

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

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用户贡献的备注 4 notes

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55
gskluzacek dot nospam at gmail dot com
14 years ago
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
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19
Knightnet
17 years ago
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.
up
19
Nitrogen
15 years ago
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.
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6
James at enfsolar dot com
5 years ago
<?php

class MyClass{

public function hello($str)

{

echo 'hello ' . $str;

}

}

$obj = new MyClass();

[$obj, 'hello']('World'); // the array can be called as a function
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备份地址：http://www.lvesu.com/blog/php/function.call-user-func.php