call_user_func_array()

(PHP 4 >= 4.0.4, PHP 5, PHP 7)

调用回调函数，并把一个数组参数作为回调函数的参数

说明

把第一个参数作为回调函数（$callback）调用，把参数数组作（$param_arr）为回调函数的的参数传入。

参数

被调用的回调函数。

要被传入回调函数的数组，这个数组得是索引数组。

返回值

返回回调函数的结果。如果出错的话就返回FALSE

更新日志

范例

Example #1call_user_func_array()例子

以上例程的输出类似于：

foobar got one and two
foo::bar got three and four

Example #2call_user_func_array()使用命名空间的情况

以上例程的输出类似于：

Hello Hannes!
Hello Philip!

把完整的函数作为回调传入call_user_func_array()

以上例程会输出：

int(8)

传引用

以上例程会输出：

function mega $a=55
global $bar=55

注释

PHP 5.4之前，如果$param_arr里面的参数是引用传值，那么不管原函数默认的各个参数是不是引用传值，都会以引用方式传入到回调函数。虽然以引用传值这种方式来传递参数给回调函数，不会发出不支持的警告，但是不管怎么说，这样做还是不被支持的。并且在PHP 5.4里面被去掉了。而且，这也不适用于内部函数，for which the function signature is honored。如果回调函数默认设置需要接受的参数是引用传递的时候，按值传递，结果将会输出一个警告。call_user_func()将会返回FALSE（there is, however, an exception for passed values with reference count = 1, such as in literals, as these can be turned into references without ill effects — but also without writes to that value having any effect —; do not rely in this behavior, though, as the reference count is an implementation detail and the soundness of this behavior is questionable）。Note:

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

• call_user_func() 把第一个参数作为回调函数调用
• callback类型的信息
• ReflectionFunction::invokeArgs() Invokes function args
• ReflectionMethod::invokeArgs() 带参数执行

As of PHP 5.6 you can utilize argument unpacking as an alternative to call_user_func_array, and is often 3 to 4 times faster.

Benchmarks from https://gist.github.com/nikic/6390366
cufa  with 0 args took 0.43453288078308
switch with 0 args took 0.24134302139282
unpack with 0 args took 0.12418699264526
cufa  with 5 args took 0.73408579826355
switch with 5 args took 0.49595499038696
unpack with 5 args took 0.18640494346619
cufa  with 100 args took 5.0327250957489
switch with 100 args took 5.291127204895
unpack with 100 args took 1.2362589836121

Just hope this note helps someone (I killed the whole day on issue).
If you use something like this in PHP 
For anyone looking for the means to test for the first parameter before passing to this function, look at the is_callable (http://php.net/manual/en/function.is-callable.php) variable handler. 
It appears that when PHP executes something like:
$a = array(1,2,3);
$b =& $a[1];
both $b and $a[1] are converted into references to a common value -- makes sense until you transfer that to a call_user_func:
call_user_func_array('foo', $a);
suddenly, inside foo, the second parameter is passed by reference!
And you can't call this wrong, only another subtly of references.
Note it appears that ksort($a) will remove the reference as well as put the elements in key order so you (probably) get what you expect. (see below on the use of a foreach ($a as &v).)
Just a heads up, the second parameter MUST be an array if it's specified, but that doesn't seem to be enforced until ~5.3.
I just pulled my hair out with an old installation of CakePHP because it was passing NULL instead of an empty array.
Please note, that when calling call_user_func_array() to redirect parameters between inherited classes, you should not use $this, because $this always refers to the class which has been instantiated. The following code even seems to crash PHP (PHP does not report error but the process simply terminates), because the the parameters are redirected only one level up (to class foo_bar2):

Instead, use the direct name of the class as string or, better, the magic constant __CLASS__ in call_user_func_array(), like:
  call_user_func_array(array(__CLASS__, 'parent::__construct'), $constructorArgs);
Then the parameters will be correctly redirected to the lowest base class.
Those having the passing by reference issue can use this simple hack.
I´m really not sure WHY this works, but it does, and it does not make use of EVAL or other questionable functions.

All it´s doing is copying the args ($args) into a new array ($Args) by reference, which i would think would be identical to the original array in every way (that matters).
Note the code here is an example of usage. The actual hack is denoted by comments.
If someone knows a better alternative, by all means, i would love to see it.
$param_arr may be empty, though it can't be null.

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