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

call_user_func_array(callable $callback,array $param_arr): mixed

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

$callback

被调用的回调函数。

$param_arr

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

<?php
function foobar($arg, $arg2) {
    echo __FUNCTION__, " got $arg and $arg2\n";
}
class foo {
    function bar($arg, $arg2) {
        echo __METHOD__, " got $arg and $arg2\n";
    }
}
// Call the foobar() function with 2 arguments
call_user_func_array("foobar", array("one", "two"));
// Call the $foo->bar() method with 2 arguments
$foo = new foo;
call_user_func_array(array($foo, "bar"), array("three", "four"));
?>

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

<?php
namespace Foobar;
class Foo {
    static public function test($name) {
        print "Hello {$name}!\n";
    }
}
// As of PHP 5.3.0
call_user_func_array(__NAMESPACE__ .'\Foo::test', array('Hannes'));
// As of PHP 5.3.0
call_user_func_array(array(__NAMESPACE__ .'\Foo', 'test'), array('Philip'));
?>

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()

<?php
$func = function($arg1, $arg2) {
    return $arg1 * $arg2;
};
var_dump(call_user_func_array($func, array(2, 4))); /* As of PHP 5.3.0 */
?>

以上例程会输出：

int(8)

传引用

<?php
function mega(&$a){
    $a = 55;
    echo "function mega \$a=$a\n";
}
$bar = 77;
call_user_func_array('mega',array(&$bar));
echo "global \$bar=$bar\n";
?>

以上例程会输出：

function mega $a=55
global $bar=55

注释

Note:

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.
<?php
function foo ($a, $b) {
   return $a + $b;
}
$func = 'foo';
$values = array(1, 2);
call_user_func_array($func, $values); 
//returns 3
$func(...$values);
//returns 3
?>
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 < 5.3:
<?php call_user_func_array(array($this, 'parent::func'), $args); ?>
Such a script will cause segmentation fault in your webserver.
In 5.3 you should write it:
<?php call_user_func_array('parent::func', $args); ?>

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.
<?php
$handler = array( 'MyClass', 'MyMethod');
$params = array(1,2,3,4);
if ( is_callable($handler) ) { call_user_func_array( $handler , $params ); }
?>

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):
<?php
  class foo_bar1
  {
    public function __construct()
    {
      echo __CLASS__ . PHP_EOL;
      if (func_num_args() > 0)
      {
        $constructorArgs = func_get_args();
        call_user_func_array(array($this, 'parent::__construct'), $constructorArgs);
      }
      else
      {
        parent::__construct();
      }
    }
  }
  class foo_bar2 extends foo_bar1
  {
    public function __construct()
    {
      echo __CLASS__ . PHP_EOL;
      if (func_num_args() > 0)
      {
        $constructorArgs = func_get_args();
        call_user_func_array(array($this, 'parent::__construct'), $constructorArgs);
      }
      else
      {
        parent::__construct();
      }
    }
  }
  class foo_bar3 extends foo_bar2
  {
    public function __construct()
    {
      echo __CLASS__ . PHP_EOL;
      if (func_num_args() > 0)
      {
        $constructorArgs = func_get_args();
        call_user_func_array(array($this, 'parent::__construct'), $constructorArgs);
      }
      else
      {
        parent::__construct();
      }
    }
  }
  $f = new foo_bar3("abc");
?>
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.
<?php
  function executeHook($name, $type='hooks'){
    $args = func_get_args();
    array_shift($args);
    array_shift($args);
    //Rather stupid Hack for the call_user_func_array();
    $Args = array();
    foreach($args as $k => &$arg){
      $Args[$k] = &$arg;
    }
    //End Hack
    $hooks = &$this->$type;
    if(!isset($hooks[$name])) return false;
    $hook = $hooks[$name];
    call_user_func_array($hook, $Args);
  }
?>
All it´s doing is copying the args ($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.
<?php
function foo( $first = 'default1', $second = 'default2' ) {
  echo "first: '$first', second: '$second'\n";
}
call_user_func_array( 'foo', array( 'one', 'two' ) );
call_user_func_array( 'foo', array( 'only one' ) );
call_user_func_array( 'foo', array() );
call_user_func_array( 'foo', null );
?>
Output:
first: 'one', second: 'two'
first: 'only one', second: 'default2'
first: 'default1', second: 'default2'
/* error message or nothing printed depending on version */

There's a possibility that call_user_func_array(), call_user_func(), and Exception::getTrace() will cause a trace entry to not have the 'file' or 'line' elements.
Dustin Oprea

Be aware the call_user_func_array always returns by value, as demonstrated here...
<?php  
  function &foo(&$a)
  {
   return $a;
  }
  
  $b = 2;
  $c =& call_user_func_array('foo', array(&$b));
  $c++;
  echo $b . ' ' . $c;  
?>
outputs "2 3", rather than the expected "3 3".
Here is a function you can use in place of call_user_func_array which returns a reference to the result of the function call. 
<?php
  function &ref_call_user_func_array($callable, $args)
  {
    if(is_scalar($callable))
    {
      // $callable is the name of a function
      $call = $callable;
    }
    else
    {
      if(is_object($callable[0]))
      {
        // $callable is an object and a method name
        $call = "\$callable[0]->{$callable[1]}";
      }
      else
      {
        // $callable is a class name and a static method
        $call = "{$callable[0]}::{$callable[1]}";
      }
    }
    
    // Note because the keys in $args might be strings
    // we do this in a slightly round about way.
    $argumentString = array();
    $argumentKeys = array_keys($args);
    foreach($argumentKeys as $argK)
    {
      $argumentString[] = "\$args[$argumentKeys[$argK]]";
    }
    $argumentString = implode($argumentString, ', ');
    // Note also that eval doesn't return references, so we 
    // work around it in this way...  
    eval("\$result =& {$call}({$argumentString});");
    return $result;
  }
?>

call_user_func_array() is nifty for calling PHP functions which use variable argument length. For example:
<?php
$array = array(
 array("foo", "bar"),
 array("bat", "rat"),
);
$values = call_user_func_array("array_merge", $array);
var_dump($values);
?>
/* output:
array(4) {
 [0]=>
 string(3) "foo"
 [1]=>
 string(3) "bar"
 [2]=>
 string(3) "bat"
 [3]=>
 string(3) "rat"
}
*/
The neat feature is that $array could have any number of arrays inside it.

<?php
namespace Foobar;
class Foo {
  
  public $email;
  public $name;
  public $age;
  
  public function setEmail($email) {
    $this->email = $email;
  }
  public function setName($name) {   
    $this->name = $name;
  }
  public function setAge($age) {   
    $this->age = $age;
  }
}
function getFields() {
  return [
    "age" => 112,
    "email" => "lol@lol.fr",
    "name" => "lol"
  ];
}
$foo = new Foo();
$callables = ["email" => $email,"name" => $name,"age" => $age] = getFields();
foreach ($callables as $func => $value) {
  call_user_func(array($foo,sprintf("set%s",ucfirst($func))),$value));
}
var_dump($foo);

In response to admin at torntech dot com and as shown on https://gist.github.com/nikic/6390366, there is no good reason to use argument unpacking anymore for PHP 7.0.17, 7.1.3, 7.2.7
7.0.17
cufa with 0 args took 0.081735849380493
unpack with 0 args took 0.072259902954102
cufa with 100 args took 0.39941906929016
unpack with 100 args took 0.419842004776
7.1.3
cufa with 0 args took 0.074923992156982
unpack with 0 args took 0.07165002822876
cufa with 100 args took 0.37423300743103
unpack with 100 args took 0.41387891769409
7.2.7
cufa with 0 args took 0.064092874526978
unpack with 0 args took 0.048593997955322
cufa with 100 args took 0.35412693023682
unpack with 100 args took 0.36837601661682

call_user_func_array can pass parameters as reference:
<?php
call_user_func_array(array(&$obj,$method),array(&$arg1,$arg2,$arg3))
?>
Use it as work-around for "Call-time pass-by-reference has been deprecated".

If you're thinking call_user_func_array has changed the array of multiple parameters to a string, remember that it does not pass the array through to the called function as a single argument (array), but creates one argument for each element in the array.

Regarding the comments below about calling parent constructors:
PHP5 with E_STRICT no longer allows calls as below:
<?php
// Causes an error with E_STRICT
call_user_func_array(array('parent', '__construct'), $args);
?>
It gives an error because you are trying to call a nonstatic function as if it was static. The correct syntax is
<?php
// Works fine
call_user_func_array(array($this, 'parent::__construct'), $args);
?>

For those wishing to implement call-by-name functionality in PHP, such as implemented e.g. in DB apis, here's a quick-n-dirty version for PHP 5 and up
<?php
/**
 * Call a user function using named instead of positional parameters.
 * If some of the named parameters are not present in the original function, they
 * will be silently discarded.
 * Does no special processing for call-by-ref functions...
 * @param string $function name of function to be called
 * @param array $params array containing parameters to be passed to the function using their name (ie array key)
 */
function call_user_func_named($function, $params)
{
  // make sure we do not throw exception if function not found: raise error instead...
  // (oh boy, we do like php 4 better than 5, don't we...)
  if (!function_exists($function))
  {
    trigger_error('call to unexisting function '.$function, E_USER_ERROR);
    return NULL;
  }
  $reflect = new ReflectionFunction($function);
  $real_params = array();
  foreach ($reflect->getParameters() as $i => $param)
  {
    $pname = $param->getName();
    if ($param->isPassedByReference())
    {
      /// @todo shall we raise some warning?
    }
    if (array_key_exists($pname, $params))
    {
      $real_params[] = $params[$pname];
    }
    else if ($param->isDefaultValueAvailable()) {
      $real_params[] = $param->getDefaultValue();
    }
    else
    {
      // missing required parameter: mark an error and exit
      //return new Exception('call to '.$function.' missing parameter nr. '.$i+1);
      trigger_error(sprintf('call to %s missing parameter nr. %d', $function, $i+1), E_USER_ERROR);
      return NULL;
    }
  }
  return call_user_func_array($function, $real_params);
}
?>

I came up with a better solution to the problem that I solve below with createObjArray that maintains parameter type:
<?php
function createObjArray($type,$args=array()) {
   $paramstr = '';
   for ($i = 0; $i < count($args); $i++) {
      $paramstr .= '$args['.$i.'],';
   }
   $paramstr = rtrim($paramstr,',');
   return eval("return new $type($paramstr);");
}
?>
Would be good to add error checking, but it works.

<?php
Class Delegate
{
  private $arrInstances = array();
  
  protected function addObject( $oElement )
  {
    // add one element on the end of the stack //
    $this->arrInstances[] = $oElement;
  }  
  
  public function __call( $strMethod, $arrParams )
  {
    // for each element in instance //
    foreach( $this->arrInstances as $oElement )
    {
      // get the class of the element //
      $strClass = get_class( $oElement );
      // get all methods of the class //
      $arrMethods = get_class_methods( $strClass );
      // case the method exists into this class //
      if( in_array( $strMethod , $arrMethods ) ) 
      {
        // prepare caller //
        $arrCaller = Array( $strClass , $strMethod );
        // return the result of the method into the object //
        return call_user_func_array( $arrCaller, $arrParams );
      }
    }
    // any object has the method //
    // throw a exception //
    throw new Exception( " Method " . $strMethod . " not exist in this class " . get_class( $this ) . "." );
  }
}
class Log
{
  public function sayHi()
  {
    print "hi!" . "<br/>\n";
  }
  
  public function sayMyName()
  {
    print "log" . "<br/>\n";
  }
}
class Other
{
  public function sayHello()
  {
    print "hello there!" . "<br/>\n";
  }
  
  public function sayMyName()
  {
    print "other" . "<br/>\n";
  }
}
class Example extends Delegate
{
  public function __construct()
  {
    $this->addObject( new Log() );
    $this->addObject( new Other() );
  }
}
$oExample = new Example();
$oExample->sayHi();
$oExample->sayHello();
$oExample->sayMyName();
/* 
  hi!<br/>
  hello there!<br/>
  log<br/>
*/
?>

If you are using PHP < 5.3 and want to call the parent class' __construct() with a variable parameter list, use this:
<?php
public function __construct()
{
  $vArgs = func_get_args(); // you can't just put func_get_args() into a function as a parameter
  call_user_func_array(array('parent', '__construct'), $vArgs);
}
?>

An implementation where parameters are submitted by their name.
This function calls class functions, class methods, functions and anonymous functions.
/**
  * Calls a method, function or closure. Parameters are supplied by their names instead of their position.
  * @param $call_arg like $callback in call_user_func_array()
  * Case1: {object, method}
  * Case2: {class, function}
  * Case3: "class::function"
  * Case4: "function"
  * Case5: closure
  * @param array $param_array A key-value array with the parameters
  * @return result of the method, function or closure
  * @throws \Exception when wrong arguments are given or required parameters are not given.
  */
function call_user_function_named_param($call_arg, array $param_array)
{
  $Func = null;
  $Method = null;
  $Object = null;
  $Class = null;
  // The cases. f means function name
  // Case1: f({object, method}, params)
  // Case2: f({class, function}, params)
  if(is_array($call_arg) && count($call_arg) == 2)
  {
    if(is_object($call_arg[0]))
    {
      $Object = $call_arg[0];
      $Class = get_class($Object);
    }
    else if(is_string($call_arg[0]))
    {
      $Class = $call_arg[0]; 
    }
    if(is_string($call_arg[1]))
    {
      $Method = $call_arg[1];
    }
  }
  // Case3: f("class::function", params)
  else if(is_string($call_arg) && strpos($call_arg, "::") !== FALSE)
  {
    list($Class, $Method) = explode("::", $call_arg);
  }
  // Case4: f("function", params)
  else if(is_string($call_arg) && strpos($call_arg, "::") === FALSE)
  {
    $Method = $call_arg;
  }
  // Case5: f(closure, params)
  else if(is_object($call_arg) && $call_arg instanceof \Closure)
  {
    $Method = $call_arg;
  }
  else throw new \Exception("Case not allowed! Invalid Data supplied!");
  if($Class) $Func = new \ReflectionMethod($Class, $Method);
  else $Func = new \ReflectionFunction($Method);
  $params = array();
  foreach($Func->getParameters() as $Param)
  {
    if($Param->isDefaultValueAvailable()) $params[$Param->getPosition()] = $Param->getDefaultValue();
    if(array_key_exists($Param->name, $param_array)) $params[$Param->getPosition()] = $param_array[$Param->name];
    if(!$Param->isOptional() && !isset($params[$Param->getPosition()])) die("No Defaultvalue available and no Value supplied!\r\n");
  }
  if($Func instanceof \ReflectionFunction) return $Func->invokeArgs($params);
  if($Func->isStatic()) return $Func->invokeArgs(null, $params);
  else return $Func->invokeArgs($Object, $params);
}
//Test code:
function func($arg1, $arg2 = "Jane")
{
  return $arg1 . "," . $arg2;
}
class tc1
{
  public static function func1($Arg1, $Arg2 = "HH")
  {
    return $Arg1 . " " . $Arg2;
  }
}
$func2 = function($a1, $a2)
{
  return "a1:" . $a1 . ", a2:" . $a2; 
};
$ret = call_user_function_named_param('func', array("arg1"=>"Hello", "arg2"=>"Joe"));
echo "Call Return:" . print_r($ret, true) . PHP_EOL;
$ret = call_user_function_named_param(array(new tc1(), 'func1'), array("Arg1"=>"Hello", "Arg2"=>"Joe"));
echo "Call2 Return:" . print_r($ret, true) . PHP_EOL;
$ret = call_user_function_named_param($func2, array("a1"=>"Hello", "a2"=>"Joe"));
echo "Call3 Return:" . print_r($ret, true) . PHP_EOL;

For those of you that have to consider performance: it takes about 3 times as long to call the function this way than via a straight statement, so whenever it is feasible to avoid this method it's a wise idea to do so.
Note that eval() is about 10 times slower than a straight statement to call a function with arguments, so this is definitely a better option than using eval() even if you only consider performance.

Kris dot Craig at gmail dot com dispatch table does not work currently, but this does.
<?php
define("YOUR_MOTHER", 1);
define("YOUR_FATHER", 2);
define("YOUR_BROTHER", 3);
define("YOUR_SISTER", 4);
class MyFamily
{
  static $dispatch = array(
    YOUR_MOTHER => "mom",
    YOUR_FATHER => "getPrisonInmate",
    YOUR_BROTHER => "replaceName",
    YOUR_SISTER => "lazyGirl");
  static $args = array(
    YOUR_MOTHER => array(),
    YOUR_FATHER => array(
      "55170-054",
      TRUE,
      3),
    YOUR_BROTHER => array(),
    YOUR_SISTER => array());
  function getDispatch($fromwhere)
  {
    return call_user_func_array(array(
      get_class(),
      self::$dispatch[$fromwhere]), self::$args[$fromwhere]);
  }
  function mom()
  {
    return "Mommy loves you!";
  }
  function getPrisonInmate($PrisonerID, $GoodBehavior, $remaining,
      $notes = null)
  {
    //Check prison records for his ID, then....
    if ($GoodBehavior)
    {
      $parole = "APPROVED";
    }
    else
    {
      $parole = "DENIED";
    }
    return "Your father (#$PrisonerID) has $remaining years left in his sentence. His most recent parole application has been: $parole";
  }
  function replaceName()
  {
    return "Her name is Sally now.";
  }
  function lazyGirl()
  {
    print "Your sister needs to get out more....";
    //sleep(pow(60, 2) * 18); //You can sleep later!
    die("Nah, I'm too tired.");
  }
}
print "Status on family member: ".MyFamily::GetDispatch(YOUR_FATHER).'<br><br>';

PLS notice that "patripaq at hotmail dot com" 's code will be valid if B EXTENDS A...
<?php
class B extends A{
...
} 
?>
there>>"What I wanted to do is create an object that can manage any number and any kind of parameters."
BUT IT IS NOT A POINT AT ALL
If you need to call just function with parameters:
call_user_func_array('Foo',$args);
If you need to call CLASS method (NOT object):
call_user_func_array(array('class', 'Foo'),$args); 
If you need to call OBJECT method:
call_user_func_array(array(&$Object, 'Foo'),$args);
If you need to call method of object of object:
call_user_func_array(array(&$Object->Object, 'Foo'),$args);
If you need to call object method from within the very same object (NOT CLASS!):
call_user_func_array(array(&$this, 'Foo'),args);
The call_user_func_array ITSELF can manage any number and any kind of parameters. It can handle ANY FUNCTION too as it is defined and that maybe partipaq wanted to manage. 
What You actually need is object composition not inheritance. Make an instance from arguments. 
<?php
...
class B{
  function __construct() {
   $args = func_get_args(); // Get arguments
   $this->OBJ = new A($args);
   call_user_func_array(array(&$this->OBJ, 'A'), $args );
  }
}
?>
Then there can be any number and any type of created object B parameters

Just an extra for the post of amer at o2 dot pl:
If you need to call the PARENT method:
call_user_func_array(array('parent', 'method'), $args);
With that, if you need to call a constructor and/or add some extra code to the instantiation process:
<?php
function __construct() {
  // Get the arguments
  $args = func_get_args();
  // Initialize parent with arguments
  call_user_func_array(array('parent', '__construct'), $args);
  // ... Your Code Here ...
}
?>
Note that your constructor pass all the arguments to the parent constructor and it doesn't matter how many arguments you pass.
This is pretty useful for constructors with a variable number of arguments.

Many people have wondered how to effectively implement dispatch tables in PHP. Here's my answer to that (if you'll forgive my creative flair):
<?php
/*
 * Using dispatch tables in PHP.
 * 
 * --Kris Craig
 */
define( "YOUR_MOTHER", 1 );
define( "YOUR_FATHER", 2 );
define( "YOUR_BROTHER", 3 );
define( "YOUR_SISTER", 4 );
class MyFamily
{
  static $dispatch = array( YOUR_MOTHER => "Mom", YOUR_FATHER => "GetPrisonInmate", YOUR_BROTHER => "ReplaceName", YOUR_SISTER => "LazyGirl" );
  static $args = array( YOUR_MOTHER => array(), YOUR_FATHER => array( "55170-054", TRUE ), YOUR_BROTHER => array(), YOUR_SISTER => array() );
  
  function GetDispatch( $fromwhere )
  {
    return call_user_func_array( array( self, self::$dispatch[$fromwhere] ), self::$args[$fromwhere] );
  }
  
  function Mom()
  {
    return "Mommy loves you!";
  }
  
  function GetPrisonInmate( $PrisonerID, $GoodBehavior )
  {
    //Check prison records for his ID, then....
    
    if ( $GoodBehavior )
    {
      $parole = "APPROVED";
    }
    else
    {
      $parole = "DENIED";
    }
    
    return "Your father (#$PrisonerID) has $remaining years left in his sentence. His most recent parole application has been: $parole";
  }
  
  function ReplaceName()
  {
    return "Her name is Sally now.";
  }
  
  function LazyGirl()
  {
    print "Your sister needs to get out more....";
    
    //sleep( pow( 60, 2 ) * 18 ); //You can sleep later!
    
    die( "Nah, I'm too tired." );
  }
}
print "Status on family member: " . MyFamily::GetDispatch( YOUR_FATHER );
?>

I just noticed that when you use this function with parameters that need to be passed by reference it will not work.
<?php
function refFunc(&$var)
{
 $var .= 'bar';
}
$var = 'foo';
?>
call_user_func_array('refFunc', array($var));
echo $var;
will output 'foo' and not 'foobar'. Witch is logical since you are declaring a new variable with array($var) however not so obvious.

<?php
 return call_user_func_array(
  array(new ReflectionClass($className), 'newInstance'),
  $functionParameters
 );
?>
Look here: http://www.zend.com/zend/week/week182.php#Heading1

Note that call_user_func() will completely trash debug_backtrace().
Solution:
<?php
your_function(...call_user_func())
?>
Note the 3 dots (array unpacking syntax).

Before PHP 7.1.0, if you call a function without passing required arguments, a warning was generated, and the missing arguments defaulted to NULL.
In PHP 7.1.0, an ArgumentCountError is being thrown instead. (A little bit of nuisance IMHO, because it causes compatibility issues).
When you use <? call_user_func_array() ?>, same behavior applies - the exception is thrown if you missed arguments.
Here's a quick and dirty fix for it:
<?
function call_user_func_array_i($callbk,$args) {
  while(true) {
    try {
      return call_user_func_array($callbk,$args);
    } catch(ArgumentCountError $e) {
      $args[] = NULL;
    }
  }
}
?>
Replace your calls to <? call_user_func_array() ?> with <? call_user_func_array_i() ?>, and the good old behavior is back (except that it doesn't issue a warning, but you probably didn't need it anyway).

Note that, despite the name, this does work on builtin functions (and object methods with the array(&$obj, $method) syntax), not just user-defined functions and methods.

If you are thinking of using call_user_func_array to instantiate an object (see comments below using Reflection) then since v5.1.3 you can use the Reflection::newInstanceArgs() method.
<?php
// arguments you wish to pass to constructor of new object
$args = array('a', 'b');
// class name of new object
$className = 'myCommand';
// make a reflection object
$reflectionObj = new ReflectionClass($className);
// use Reflection to create a new instance, using the $args
$command = $reflectionObj->newInstanceArgs($args);
// this is the same as: new myCommand('a', 'b');
?>

Here is another version of createObjArray() function written here earlier by taylor.
Believing that using 'eval()' is at least "dirty", I came to the following solution (with a help of panchous - at phpclub dot ru forums ). This solution utilizes the new Reflection API.
<?php
function & createObjArray($type, $args = array()) {
  $reflection = new ReflectionClass($type);
  $output   = call_user_func_array(array(&$reflection, 'newInstance'), $args);
  return $output;
}
?>

This function is relatively slow (as of PHP 5.3.3) and if you are calling a method with a known number of parameters it is much faster to call it this way:
$class->{$method}($param1, $param2);
vs
call_user_func_array (array($class, $method), array($param1, $param2));
But if you don't know how many parameters...
The wrapper function below is slightly faster, but the problem now is that you are making two function calls. One to the wrapper and one to the function.
However, If you are able to take this code out of the function and use it inline it is nearly twice as fast (in most cases) as calling call_user_func_array natively.
<?php
function wrap_call_user_func_array($c, $a, $p) {
  switch(count($p)) {
    case 0: $c->{$a}(); break;
    case 1: $c->{$a}($p[0]); break;
    case 2: $c->{$a}($p[0], $p[1]); break;
    case 3: $c->{$a}($p[0], $p[1], $p[2]); break;
    case 4: $c->{$a}($p[0], $p[1], $p[2], $p[3]); break;
    case 5: $c->{$a}($p[0], $p[1], $p[2], $p[3], $p[4]); break;
    default: call_user_func_array(array($c, $a), $p); break;
  }
}
?>

I've found the solution to resolve my need while writing the str_replace function for processing the multi array as first two arguments of str_replace built-in function(although its pass each array of argument 1 & 2)
<?php
// custom the str_replace function
function p_str_replace($argFind, $agrReplace, $theString) {
 $needle_replace = $theString; // handle the string need to be replace
 array_walk($argFind, function($val, $key) use(&$needle_replace, $agrReplace) {
  $needle_replace = call_user_func_array('str_replace', array($val, $agrReplace[$key], $needle_replace));
 });
 return $needle_replace;
}
// test
$the_str = array(
 'coa' => ':col: :op1: :val: AND :col: :op2: :val:'
);
$ope = array('>=', '<=');
$colsdata = array('date_start', '2015-10-14');
echo p_str_replace(array(
     array(':col:', ':val:'),
     array(':op1:', ':op2:')
    ), array(
      $colsdata,
      $ope
    ), $the_str['coa']);
echo '-------------------------------' . "\n";
// more complexity
$complex = '(:col: :op1: :val: AND :col: :op2: :val:) AND (:col2: :op1: :val2: AND :col2: :op1: :val2:)';
echo p_str_replace(array(
 array(':col:', ':val:'),
 array(':col2:', ':val2:'),
 array(':op1:', ':op2:')
), array(
 array('date_start', '2015-10-01'),
 array('date_end', '2015-10-14'),
 array('>', '<')
), $complex);
?>
Sorry about my bad English :)
Hope this help someone.