Anonymous (2011-06-27 11:20:48)

$ wget http://www.php.net/get/php_manual_en.tar.gz/from/a/mirror
$ grep -l "\$\.\.\." php-chunked-xhtml/function.*.html

List of functions that accept variable arguments.
<?php
array_diff_assoc()
array_diff_key()
array_diff_uassoc()
array()
array_intersect_ukey()
array_map()
array_merge()
array_merge_recursive()
array_multisort()
array_push()
array_replace()
array_replace_recursive()
array_unshift()
call_user_func()
call_user_method()
compact()
dba_open()
dba_popen()
echo()
forward_static_call()
fprintf()
fscanf()
httprequestpool_construct()
ibase_execute()
ibase_set_event_handler()
ibase_wait_event()
isset()
list()
maxdb_stmt_bind_param()
maxdb_stmt_bind_result()
mb_convert_variables()
newt_checkbox_tree_add_item()
newt_grid_h_close_stacked()
newt_grid_h_stacked()
newt_grid_v_close_stacked()
newt_grid_v_stacked()
newt_win_choice()
newt_win_entries()
newt_win_menu()
newt_win_message()
newt_win_ternary()
pack()
printf()
register_shutdown_function()
register_tick_function()
session_register()
setlocale()
sprintf()
sscanf()
unset()
var_dump()
w32api_deftype()
w32api_init_dtype()
w32api_invoke_function()
wddx_add_vars()
wddx_serialize_vars()
?>

imurnane at internode on net (2011-05-02 03:05:23)

Create and call a dynamically named function

<?php
$tmp = "foo";
$$tmp = function() {
    global $tmp;
    echo $tmp;
}; 

$$tmp();
?>

Outputs "foo"

michalmojz at gmail dot com (2011-01-29 13:51:20)

You can make dynamic functions as well. 

For example

<?php
$myFunction = function() {
      echo 1;
};

if(is_callable($myFunction)) {
      $myFunction();
}
?>

AnonymousPoster at disposeamail dot com (2010-05-03 14:20:54)

Variable functions allows higher-order programming.

Here is the classical map example.

<?php
/*
 * Map function. At each $element of the $list, calls $fun([$arg1,[$arg2,[...,]],$element,$accumulator),
 *      stores the return value into $accumulator for the next loop. Returns the last return value of the function,
 *
 * Notes : uses call_user_func_array() so passing parameters doesn't depend on $fun signature
 *          It also returns FALSE upon error.
 *          Please check the php documentation for more information
 */
function map($fun, $list,$params=array()){
    $acc=NULL;
    $last=array_push($params, NULL,$acc)-1; // alloc $element and $acc at the end
    foreach($list as $params[$last-1]){
        $params[$last]=call_user_func_array($fun , $params  );
    }
    $acc=array_pop($params);
    return $acc;
}

function add($element,$acc){ // maybe only with multi-length function
    if ($acc == NULL);
    return $acc=$element+$acc;
}

$result=0;
$result=addTo($result,1);
$result=addTo($result,2);
$result=addTo($result,3);
echo "result = $result\n";

$result=0;
$result=map('addTo',array(1,2,3));
echo "result= $result\n";
?>

boards at gmail dot com (2006-01-22 10:07:14)

If you want to call a static function (PHP5) in a variable method:

Make an array of two entries where the 0th entry is the name of the class to be invoked ('self' and 'parent' work as well) and the 1st entry is the name of the function.  Basically, a 'callback' variable is either a string (the name of the function) or an array (0 => 'className', 1 => 'functionName').

Then, to call that function, you can use either call_user_func() or call_user_func_array().  Examples:

<?php
class A {

  protected $a;
  protected $c;

  function __construct() {
    $this->a = array('self', 'a');
    $this->c = array('self', 'c');
  }

  static function a($name, &$value) {
    echo $name,' => ',$value++,"\n";
  }

  function b($name, &$value) {
    call_user_func_array($this->a, array($name, &$value));
  }

  static function c($str) {
    echo $str,"\n";
  }

  function d() {
    call_user_func_array($this->c, func_get_args());
  }

  function e() {
    call_user_func($this->c, func_get_arg(0));
  }

}

class B extends A {

  function __construct() {
    $this->a = array('parent', 'a');
    $this->c = array('self', 'c');
  }

  static function c() {
    print_r(func_get_args());
  }

  function d() {
    call_user_func_array($this->c, func_get_args());
  }

  function e() {
    call_user_func($this->c, func_get_args());
  }

}

$a =& new A;
$b =& new B;
$i = 0;

A::a('index', $i);
$a->b('index', $i);

$a->c('string');
$a->d('string');
$a->e('string');

# etc.
?>

Storm (2005-05-03 08:34:47)

This can quite useful for a dynamic database class:

(Note: This just a simplified section)

<?php
class db {

    private $host = 'localhost';
    private $user = 'username';
    private $pass = 'password';
    private $type = 'mysqli';
    
    public $lid = 0;

    // Connection function
    function connect() {
        $connect = $this->type.'_connect';
            
        if (!$this->lid = $connect($this->host, $this->user, $this->pass)) {
            die('Unable to connect.');
        }
 }
}
$db  = new db;
$db->connect();
?>

Much easier than having multiple database classes or even extending a base class.

ian at NO_SPAM dot verteron dot net (2002-12-20 07:33:25)

A good method to pass around variables containing function names within some class is to use the same method as the developers use in preg_replace_callback - with arrays containing an instance of the class and the function name itself.
function call_within_an_object($fun)
{
if(is_array($fun))
{
/* call a function within an object */
$fun[0]->{$fun[1]}();
}
else
{
/* call some other function */
$fun();
}
}
function some_other_fun()
{
/* code */
}
class x
{
function fun($value)
{
/* some code */
}
}
$x = new x();
/* the following line calls $x->fun() */
call_within_an_object(Array($x, 'fun'));
/* the following line calls some_other_fun() */
call_within_an_object('some_other_fun');

madeinlisboa at yahoo dot com (2002-09-05 05:14:05)

Finally, a very easy way to call a variable method in a class:
Example of a class:
class Print() {
var $mPrintFunction;
function Print($where_to) {
$this->mPrintFunction = "PrintTo$where_to";
}
function PrintToScreen($content) {
echo $content;
}
function PrintToFile($content) {
fputs ($file, $contents);
}
.. .. ..
// first, function name is parsed, then function is called
$this->{$this->mPrintFunction}("something to print");
}

msmith at pmcc dot com (2002-05-02 16:49:39)

Try the call_user_func() function. I find it's a bit simpler to implement, and at very least makes your code a bit more readable... much more readable and simpler to research for someone who isn't familiar with this construct.

anpatel at NOSPAM_cbu dot edu (2002-03-17 21:11:22)

Yes interpolation can be very tricky. I suggest that you always use parenthesis, or curly brackets(whichever applies) to make your expression clear.
Dont ever depend on a language's expression parse preference order.

retro at enx dot org (2002-01-13 19:18:07)

Another way to have php parse a variable within an object as a function is to simply set a temporary variable to its value. For example:
$obj->myfunction = "foo";
$x = $obj->myfunction;
$x(); // calls the function named "foo"