Retornando valores
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');
$a->e('string');
# etc.
?>
Funções variáveis
O PHP suporta o conceito de funções variáveis. Isto significa que se um nome de variável tem parênteses no final dela, o PHP procurará uma função com o mesmo nome, qualquer que seja a avaliação da variável, e tentará executá-la. Entre outras coisas, isto pode ser usado para implementar callbacks, tabelas de função e assim por diante.
Funções variáveis não funcionam com construtores de linguagem como echo, print, unset(), isset(), empty(), include, require e outras assim. Utilize uma função de wrapper para usar quaisquer um destes construtores como uma função variável.
Exemplo #1 Exemplo de funções variáveis
<?php
function foo() {
echo "Chamou foo()<br>\n";
}
function bar($arg = '')
{
echo "Chamou bar(); com argumento '$arg'.<br />\n";
}
// Essa eh uma funcao wrapper para echo()
function echoit($string)
{
echo $string;
}
$func = 'foo';
$func(); // Chama foo()
$func = 'bar';
$func('test'); // Chama bar()
$func = 'echoit';
$func('test'); // Chama echoit()
?>
Um metodo de um objeto também pode ser chamado com a sintaxe de funções variáveis.
Exemplo #2 Exemplo de chama de método variável
<?php
class Foo
{
function MetodoVariavel()
{
$name = 'Bar';
$this->$name(); // Isto chama o método Bar()
}
function Bar()
{
echo "Bar foi chamada!";
}
}
$foo = new Foo();
$funcname = "MetodoVariavel";
$foo->$funcname(); // Isto chama $foo->MetodoVariavel()
?>
Veja também call_user_func(), variáveis variáveis e function_exists().
add a note
User Contributed Notes
Funções variáveis - [11 notes]
boards at gmail dot com ¶
7 years ago
ian at NO_SPAM dot verteron dot net ¶
10 years ago
A good method to pass around variables containing function names within some class is to use the same method as the developers use in preg_replace_callback - with arrays containing an instance of the class and the function name itself.
function call_within_an_object($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');
anpatel at NOSPAM_cbu dot edu ¶
11 years ago
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.
imurnane at internode on net ¶
2 years ago
Create and call a dynamically named function
<?php
$tmp = "foo";
$$tmp = function() {
global $tmp;
echo $tmp;
};
$$tmp();
?>
Outputs "foo"
madeinlisboa at yahoo dot com ¶
10 years ago
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");
}
AnonymousPoster at disposeamail dot com ¶
2 years ago
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";
?>
msmith at pmcc dot com ¶
11 years ago
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.
Storm ¶
7 years ago
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.
Anonymous ¶
1 year ago
$ 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()
?>
michalmojz at gmail dot com ¶
2 years ago
You can make dynamic functions as well.
For example
<?php
$myFunction = function() {
echo 1;
};
if(is_callable($myFunction)) {
$myFunction();
}
?>
retro at enx dot org ¶
11 years ago
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"