Simple function to calculate average value using dynamic arguments:
<?php
function average(){
return array_sum(func_get_args())/func_num_args();
}
print average(10, 15, 20, 25); // 17.5
?>
(PHP 4, PHP 5, PHP 7, PHP 8)
func_get_args — Devuelve un array que se compone de una lista de argumentos de función
Obtiene un array de la lista de argumentos de una función.
Esta función se puede usar junto con func_get_arg() y func_num_args() para permitir a las funciones definidas por el usuario aceptar una lista de argumentos de longitud variable.
Esta función no tiene parámetros.
Devuelve un array en el que cada elemento es una copia del miembro correspondiente de la lista de argumentos de la función definida por el usuario.
Genera una advertencia si se llama desde fuera de una función definida por el usuario.
Ejemplo #1 Ejemplo de func_get_args()
<?php
function foo()
{
$númargs = func_num_args();
echo "Número de argumentos: $númargs \n";
if ($númargs >= 2) {
echo "El segundo argumento es: " . func_get_arg(1) . "\n";
}
$arg_list = func_get_args();
for ($i = 0; $i < $númargs; $i++) {
echo "El argumento $i es: " . $arg_list[$i] . "\n";
}
}
foo(1, 2, 3);
?>El resultado del ejemplo sería:
Número de argumentos: 3 El segundo argumento es: 2 El argumento 0 es: 1 El argumento 1 es: 2 El argumento 2 es: 3
Ejemplo #2 func_get_args() ejemplo de argumentos byref (pasa un objeto como referencia) y byval (pasa un objeto como valor)
<?php
function byVal($arg) {
echo 'Pasó como : ', var_export(func_get_args()), PHP_EOL;
$arg = 'baz';
echo 'Tras el cambio : ', var_export(func_get_args()), PHP_EOL;
}
function byRef(&$arg) {
echo 'Pasó como : ', var_export(func_get_args()), PHP_EOL;
$arg = 'baz';
echo 'Tras el cambio : ', var_export(func_get_args()), PHP_EOL;
}
$arg = 'bar';
byVal($arg);
byRef($arg);
?>El resultado del ejemplo sería:
Nota:
Si los argumentos se pasan por referencia, cualquier cambio en ellos se verá reflejado en los valores devueltos por esta función. A partir de PHP 7, los valores actuales también serán devueltos si los argumentos son pasados por valor.
Nota: Esta función solamente devuelve una copia de los argumentos pasados, y no rinde cuentas de los argumentos predeterminados (no pasados).
...Simple function to calculate average value using dynamic arguments:
<?php
function average(){
return array_sum(func_get_args())/func_num_args();
}
print average(10, 15, 20, 25); // 17.5
?>If you want to get the arguments by reference, instead of func_get_args() you can simply use
<?php
function args_byref(&...$args) {
// Modify the $args array here
}
?>
Credits should go to Markus Malkusch for pointing this out on Stackoverflow.
https://stackoverflow.com/a/29181826/1426064How to create a polymorphic/"overloaded" function
<?php
function select()
{
$t = '';
$args = func_get_args();
foreach ($args as &$a) {
$t .= gettype($a) . '|';
$a = mysql_real_escape_string($a);
}
if ($t != '') {
$t = substr($t, 0, - 1);
}
$sql = '';
switch ($t) {
case 'integer':
// search by ID
$sql = "id = {$args[0]}";
break;
case 'string':
// search by name
$sql = "name LIKE '%{$args[0]}%'";
break;
case 'string|integer':
// search by name AND status
$sql = "name LIKE '%{$args[0]}%' AND status = {$args[1]}";
break;
case 'string|integer|integer':
// search by name with limit
$sql = "name LIKE '%{$args[0]}%' LIMIT {$args[1]},{$args[2]}";
break;
default:
// :P
$sql = '1 = 2';
}
return mysql_query('SELECT * FROM table WHERE ' . $sql);
}
$res = select(29); // by ID
$res = select('Anderson'); // by name
$res = select('Anderson', 1); // by name and status
$res = select('Anderson', 0, 5); // by name with limit
?><?php
// How to simulate named parameters in PHP.
// By Dave Benjamin <dave@ovumdesign.com>
// Turns the array returned by func_get_args() into an array of name/value
// pairs that can be processed by extract().
function varargs($args) {
$count = count($args);
for ($i = 0; $i < $count; $i += 2) {
$result[$args[$i]] = $args[$i + 1];
}
return $result;
}
// Example
function test(&$ref1, &$ref2) {
// Default arguments go here.
$foo = "oof";
// Do some magic.
extract(varargs(func_get_args()));
echo nl2br("\n\$var1 = $var1");
echo nl2br("\n\$var2 = $var2");
echo nl2br("\n\$foo = $foo\n\n");
// Modify some variables that were passed by reference.
// Note that func_get_args() doesn't pass references, so they
// need to be explicitly declared in the function definition.
$ref1 = 42;
$ref2 = 84;
}
$a = 5;
$b = 6;
echo nl2br("Before calling test(): \$a = $a\n");
echo nl2br("Before calling test(): \$b = $b\n");
// Try removing the 'foo, "bar"' from the following line.
test($a, $b, var1, "abc", var2, "def", foo, "bar");
echo nl2br("After calling test(): \$a = $a\n");
echo nl2br("After calling test(): \$b = $b\n");
?>Merge func_get_args() with function defaults
<?php
class utils {
/**
* @param mixed[] $args
* @param ReflectionMethod $reflectionMethod
*
* @return array
*/
public static function mergeArgsWithDefaults( $args, \ReflectionMethod $reflectionMethod ) {
foreach ( array_slice( $reflectionMethod->getParameters(), count( $args ) ) as $param ) {
/**
* @var ReflectionParameter $param
*/
$args[] = $param->getDefaultValue();
}
return $args;
}
}
class sampleParent {
const USER_FILE_TYPE_FILE = 'FILE';
public function select( $idUserFile = null, $idUserFileType = self::USER_FILE_TYPE_FILE ) {
echo '[$idUserFile=>' . $idUserFile . ', $idUserFileType=>' . $idUserFileType, ']<br/>' . PHP_EOL;
}
}
class sample extends sampleParent {
const USER_FILE_TYPE_IMG = 'IMG';
public function select( $idUserFile = null, $idUserFileType = self::USER_FILE_TYPE_IMG ) {
return call_user_func_array( 'parent::select', \utils::mergeArgsWithDefaults( func_get_args(), new ReflectionMethod( __CLASS__, __FUNCTION__ ) ) );
}
}
$sample1 = new sampleParent();
$sample1->select();//Prints "" / self::USER_FILE_TYPE_FILE
$sample1->select(1);//Prints 1 / self::USER_FILE_TYPE_FILE
$sample1->select(2, 'test 1');//Prints 2 / "test 1"
echo '<br/>' . PHP_EOL;
$sample2 = new sample();
$sample2->select();//Prints "" / self::USER_FILE_TYPE_IMG
$sample2->select(3);//Prints 3 / self::USER_FILE_TYPE_IMG
$sample2->select(4, 'test 2');//Prints 4 / "test 2"
?>please note that optional parameters are not seen/passed by func_get_args(), as well as func_get_arg().
ex:
<?php
function testfunc($optional = 'this argument is optional..') {
$args = func_get_args();
var_dump($args);
echo $optional;
}
?>
test case #1:
testfunc('argument no longer optional..');
result for #1:
array(1) {
[0]=> string(20) "argument no longer optional.."
}
argument no longer optional..
test case #2:
testfunc('argument no longer optional..','this is an extra argument');
result for #2:
array(2) {
[0]=> string(29) "argument no longer optional.."
[1]=> string(25) "this is an extra argument"
}
argument no longer optional..
test case #3: -- RESULTS IN AN EMPTY ARRAY
testfunc();
result for #3:
array(0) {
}
this argument is optional..I wanted an associative list of arguments, in case some else does too, I'm leaving it here.
I hope PHP gets native support for this, because a core implementation would be faster than this userland backtrace+reflection implementation:
<?php
/**
* Get function arguments as associative array
* (same as func_get_args() but with keys)
*
* @param bool $populateMissingArgumentsWithDefaults whether to populate the array with default values for missing arguments
*
* @return array
*/
function func_get_args_associative(bool $populateMissingArgumentsWithDefaults = false): array
{
$trace = debug_backtrace(0, 2)[1];
$reflection = null;
if (isset($trace['class'])) {
$reflection = new \ReflectionMethod($trace['class'], $trace['function']);
} else {
$reflection = new \ReflectionFunction($trace['function']);
}
$ret = [];
foreach ($reflection->getParameters() as $param) {
if (array_key_exists($param->getPosition(), $trace['args'])) {
$ret[$param->name] = $trace['args'][$param->getPosition()];
} elseif ($populateMissingArgumentsWithDefaults) {
// because of the "required arguments declared after an optional argument are implicitly required" rule:
assert($param->isDefaultValueAvailable(), "i think all params are either in trace[args] or have default values");
$ret[$param->name] = $param->getDefaultValue();
}
}
return $ret;
}
?>The size of the array resulting from func_get_args(), for instance using count(), does not take into account parameters that have been assigned default values in the function definition.
Example:
function foo($bar=true) {
echo count(func_get_args());
}
foo();
// echoes 0
foo("bar");
// echoes 1
A useful condition to test for when a function needs to return default behavior (whatever that might be) when no value is present and the value of $bar could be true, false, null, etc.it seems that this function only returns a copy and loses it's byref information, use this dirty non-efficient workaround instead:
at the moment of writing it currently returns all of them as references, instead of only the ones who are passed that way...
<?php
function func_get_args_byref() {
$trace = debug_backtrace();
return $trace[1]['args'];
}
?><?php
/*
This example demonstrate how to use unknown variable arguments by reference.
func_get_args() don't return arguments by reference, but
debug_backtrace() "args" is by reference.
In PHP 5 this have no particular sense, because calling with arguments by reference
is depreciated and produce warning.
*/
class foo {
var $bar = "default bar";
function foo(/*variable arguments*/) {
// func_get_args returns copy of arguments
// $args = func_get_args();
// debug_backtrace returns arguments by reference
$stack = debug_backtrace();
$args = array();
if (isset($stack[0]["args"]))
for($i=0; $i < count($stack[0]["args"]); $i++)
$args[$i] = & $stack[0]["args"][$i];
call_user_func_array(array(&$this, 'bar'), $args);
}
function bar($bar = NULL) {
if (isset($bar))
$this->bar = & $bar;
}
}
$global_bar = "bar global";
$foo = & new foo();
echo "foo->bar: ".$foo->bar."</br>\n";
$foo->bar = "new bar";
echo "global_bar: ".$global_bar."</br>\n";
/*
Result:
foo->bar: default bar</br>
global_bar: bar global</br>
*/
$foo = & new foo(&$global_bar);
echo "foo->bar: ".$foo->bar."</br>\n";
$foo->bar = "new bar";
echo "global_bar: ".$global_bar."</br>\n";
/*
Result:
foo->bar: bar global</br>
global_bar: new bar</br>
*/
?>"Because this function depends on the current scope to determine parameter details, it cannot be used as a function parameter. If you must pass this value, assign the results to a variable, and pass the variable."
This means that the following code generates an error:
<?php
function foo($list)
{
echo implode(', ', $list);
}
function foo2()
{
foo(func_get_args());
}
foo2(1, 2, 3);
?>
However, you can easily get around this by doing the following:
<?php
function foo($list)
{
echo implode(', ', $list);
}
function foo2()
{
foo($args = func_get_args());
}
foo2(1, 2, 3);
?>
This captures the context from foo2(), making this legal. You get the expected output:
"1, 2, 3"You can pass a variable number of arguments to a function whilst keeping references intact by using an array. The disadvantage of course, is that the called function needs to be aware that it's arguments are in an array.
<?php
// Prints "hello mutated world"
function mutator($args=null) {
$n=count($args);
while($i<$n) $args[$i++] = "mutated";
}
$a = "hello";
$b = "strange";
$c = "world";
mutator(array($a, &$b, $c));
echo "$a $b $c";
?>