Fonctions internes
Base dao class illustrating the usefulness of closures.
* Handles opening and closing of connections.
* Adds slashes sql
* Type checking of sql parameters and casts as appropriate
* Provides hook for processing of result set and emitting one or more objects.
* Provides hook for accessing underlying link and result objects.
<?php
define("userName","root");
define("password","root");
define("dbName","ahcdb");
define("hostName","localhost");
class BaseDao {
function getConnection() {
$link = mysql_connect(hostName, userName, password);
if (!$link)
die("Could not connect: " . mysql_error());
if (!mysql_select_db(dbName))
die("Could not select database: " . mysql_error());
return $link;
}
function setParams(& $sql, $params) {
if($params != null)
$sql = vsprintf($sql, array_map(function($n) {
if(is_int($n))
return (int)$n;
if(is_float($n))
return (float)$n;
if(is_string($n))
return "'".mysql_real_escape_string($n)."'";
return mysql_real_escape_string($n);
}, $params));
}
function executeQuery($sql, $params, $callback = null) {
$link = $this->getConnection();
$this->setParams($sql, $params);
$return = null;
if(($result = mysql_query($sql, $link)) != null)
if($callback != null)
$return = $callback($result, $link);
if($link != null)
mysql_close($link);
if(!$result)
die("Fatal Error: Invalid query '$sql' : " . mysql_error());
return $return;
}
function getList($sql, $params, $callback) {
return $this->executeQuery($sql, $params, function($result, $link) use ($callback) {
$idx = 0;
$list = array();
while ($row = mysql_fetch_assoc($result))
if($callback != null)
$list[$idx] = $callback($idx++, $row);
return $list;
});
}
function getSingle($sql, $params, $callback) {
return $this->executeQuery($sql, $params, function($result, $link) use ($callback) {
if ($row = mysql_fetch_assoc($result))
$obj = $callback($row);
return $obj;
});
}
}
class Example {
var $id;
var $name;
function Example($id, $name){
$this->id = $id;
$this->name = $name;
}
function setId($id){
$this->id = $id;
}
}
class ExampleDao extends BaseDao {
function getAll(){
return parent::getList("select * from nodes", null, function($idx, $row) {
return new Example($row["id"], $row["name"]);
});
}
function load($id){
return parent::getSingle("select * from nodes where id = %1\$s", array($id), function($row) {
return new Example($row["id"], $row["name"]);
});
}
function update($example){
return parent::executeQuery("update nodes set name = '' where id = -1", null, function($result, $link){
return $result;
});
}
function insert(& $example){
return parent::executeQuery("insert into nodes", null, function($result, $link) use ($example){
$id = mysql_insert_id($link);
$example->setId($id);
return $result;
});
}
}
$exampleDao = new ExampleDao();
$list = $exampleDao->getAll());
$exampleObject = $exampleDao->load(1));
$exampleDao->update($exampleObject);
?>
Fonctions anonymes
Les fonctions anonymes, aussi appelées fermetures ou closures permettent la création de fonctions sans préciser leur nom. Elles sont particulièrement utiles comme fonctions de rappel, mais leur utilisation n'est pas limitée à ce seul usage.
Exemple #1 Exemples avec des fonctions anonymes
<?php
echo preg_replace_callback('~-([a-z])~', function ($match) {
return strtoupper($match[1]);
}, 'bonjour-le-monde');
?>
Les fonctions anonymes peuvent aussi être utilisées comme valeurs de variables. PHP va automatiquement convertir ces expressions en objets Closure. Assigner une fermeture à une variable est la même chose qu'un assignement classique, y compris pour le point-virgule final.
Exemple #2 Assignation de fonction anonyme à une variable
<?php
$greet = function($name)
{
printf("Bonjour %s\r\n", $name);
};
$greet('World');
$greet('PHP');
?>
Les fonctions anonymes peuvent hériter des variables du contexte de leur parent. Ces variables doivent alors être déclarées dans la signature de la fonction. L'héritage du contexte parent n'est pas la même chose que les variables de l'environnement global. Les variables globales existent dans le contexte global, qui est le même, quelle que que soit la fonction qui s'exécute. Le contexte parent d'une fonction anonyme est la fonction dans laquelle la fonction a été déclarée (pas nécessairement celle qui appelle). Voyez l'exemple ci-dessous :
Exemple #3 Fonctions anonymes et contexte
<?php
// Un panier d'achat simple, qui contient une liste de produits
// choisis et la quantité désirée de chaque produit. Il inclut
// une méthode qui calcule le prix total des éléments dans le panier
// en utilisant une fonction de rappel anonyme.
class Panier
{
const PRICE_BEURRE = 1.00;
const PRICE_LAIT = 3.00;
const PRICE_OEUF = 6.95;
protected $products = array();
public function add($product, $quantity)
{
$this->products[$product] = $quantity;
}
public function getQuantity($product)
{
return isset($this->products[$product]) ? $this->products[$product] :
FALSE;
}
public function getTotal($tax)
{
$total = 0.00;
$callback =
function ($quantity, $product) use ($tax, &$total)
{
$pricePerItem = constant(__CLASS__ . "::PRICE_" .
strtoupper($product));
$total += ($pricePerItem * $quantity) * ($tax + 1.0);
};
array_walk($this->products, $callback);
return round($total, 2);
}
}
$mon_panier = new Panier;
// Ajout d'élément au panier
$mon_panier->add('beurre', 1);
$mon_panier->add('lait', 3);
$mon_panier->add('oeuf', 6);
// Affichage du prix avec 5.5% de TVA
print $mon_panier->getTotal(0.055) . "\n";
?>
Les fonctions anonymes sont implémentées en utilisant la classe Closure.
Historique
| Version | Description |
|---|---|
| 5.4.0 | $this peut désormais être utilisé dans les fonctions anonymes. |
| 5.3.0 | Les fonctions anonymes deviennent disponibles. |
Notes
Note: Il est possible d'utiliser les fonctions func_num_args(), func_get_arg() et func_get_args() dans une fonction anonyme.
add a note
User Contributed Notes
Fonctions anonymes - [36 notes]
anonymous ¶
2 years ago
kdelux at gmail dot com ¶
2 years ago
Here is an example of one way to define, then use the variable ( $this ) in Closure functions. The code below explores all uses, and shows restrictions.
The most useful tool in this snippet is the requesting_class() function that will tell you which class is responsible for executing the current Closure().
Overview:
-----------------------
Successfully find calling object reference.
Successfully call $this(__invoke);
Successfully reference $$this->name;
Successfully call call_user_func(array($this, 'method'))
Failure: reference anything through $this->
Failure: $this->name = '';
Failure: $this->delfect();
<?php
function requesting_class()
{
foreach(debug_backtrace(true) as $stack){
if(isset($stack['object'])){
return $stack['object'];
}
}
}
class Person
{
public $name = '';
public $head = true;
public $feet = true;
public $deflected = false;
function __invoke($p){ return $this->$p; }
function __toString(){ return 'this'; } // test for reference
function __construct($name){ $this->name = $name; }
function deflect(){ $this->deflected = true; }
public function shoot()
{ // If customAttack is defined, use that as the shoot resut. Otherwise shoot feet
if(is_callable($this->customAttack)){
return call_user_func($this->customAttack);
}
$this->feet = false;
}
}
$p = new Person('Bob');
$p->customAttack =
function(){
echo $this; // Notice: Undefined variable: this
#$this = new Class() // FATAL ERROR
// Trick to assign the variable '$this'
extract(array('this' => requesting_class())); // Determine what class is responsible for making the call to Closure
var_dump( $this ); // Passive reference works
var_dump( $$this ); // Added to class: function __toString(){ return 'this'; }
$name = $this('name'); // Success
echo $name; // Outputs: Bob
echo '<br />';
echo $$this->name;
call_user_func_array(array($this, 'deflect'), array()); // SUCCESSFULLY CALLED
#$this->head = 0; //** FATAL ERROR: Using $this when not in object context
$$this->head = 0; // Successfully sets value
};
print_r($p);
$p->shoot();
print_r($p);
die();
?>
fabiolimasouto at gmail dot com ¶
2 years ago
You may have been disapointed if you tried to call a closure stored in an instance variable as you would regularly do with methods:
<?php
$obj = new StdClass();
$obj->func = function(){
echo "hello";
};
//$obj->func(); // doesn't work! php tries to match an instance method called "func" that is not defined in the original class' signature
// you have to do this instead:
$func = $obj->func;
$func();
// or:
call_user_func($obj->func);
// however, you might wanna check this out:
$array['func'] = function(){
echo "hello";
};
$array['func'](); // it works! i discovered that just recently ;)
?>
Now, coming back to the problem of assigning functions/methods "on the fly" to an object and being able to call them as if they were regular methods, you could trick php with this lawbreaker-code:
<?php
class test{
private $functions = array();
private $vars = array();
function __set($name,$data)
{
if(is_callable($data))
$this->functions[$name] = $data;
else
$this->vars[$name] = $data;
}
function __get($name)
{
if(isset($this->vars[$name]))
return $this->vars[$name];
}
function __call($method,$args)
{
if(isset($this->functions[$method]))
{
call_user_func_array($this->functions[$method],$args);
} else {
// error out
}
}
}
// LET'S BREAK SOME LAW NOW!
$obj = new test;
$obj->sayHelloWithMyName = function($name){
echo "Hello $name!";
};
$obj->sayHelloWithMyName('Fabio'); // Hello Fabio!
// THE OLD WAY (NON-CLOSURE) ALSO WORKS:
function sayHello()
{
echo "Hello!";
}
$obj->justSayHello = 'sayHello';
$obj->justSayHello(); // Hello!
?>
NOTICE: of course this is very bad practice since you cannot refere to protected or private fields/methods inside these pseudo "methods" as they are not instance methods at all but rather ordinary functions/closures assigned to the object's instance variables "on the fly". But I hope you've enjoyed the jurney ;)
marcellorvalle at gmail dot com ¶
2 months ago
I fell uncomfortable with php's way to pass callbacks ahead. It's just a personal opinion but i think the structure array($object, 'method') a little bit ugly. In some special cases i would like to do something more verbose, like that:
<?php
$sortedArray = ArrayServices::sort($arrayOfPerson, $sortPerson->byName);
?>
Here, "$sortPerson->byName" is a pointer to a function that receives 2 instances of Person and return true if the name of the first is "bigger" than the second. "ArrayServices::sort" is a function that can sort any kind of array using different criterias, it uses the function passed on the second parameter to compare two items on the array
I am able do that defining a simple abstract class which gives the ability to it's children to expose their methods as closures using __get() magic funtion.
<?php
abstract class ClosureExposerObject
{
public function __get($methodName)
{
if (is_callable(
array($this, $methodName)))
{
return function() use ($methodName)
{
$args = func_get_args();
return call_user_func_array(array($this, $methodName), $args);
};
}
else
{
$className = get_class($this);
throw new \BadMethodCallException("$method is not a callable at $className class.");
}
}
}
?>
Now it is possible to define a class SortPerson so that i could use it like in the first code snippet.
<?php
class SortPerson extends ClosureExposerObject
{
public function byName(Person p1, Person p2)
{
return p1->getName() > p2->getName();
}
public function byAge(Person p1, Person p2)
{
return p1->getAge() > p2->getAge();
}
public function bySurName(Person p1, Person p2)
(...)
}
?>
I just needed to extend ClosureExposerObject and do nothing more.
Some observations: SortPerson is a service class but i decided not to implement it with static methods. It is a personal matter but i really dont like to implement such small classes with statics. Also i have inverted some naming conventions (class names as substantives and methods as verbs) but in some very special cases i thing that it actually helps readability.
Suman Madavapeddi. ¶
2 years ago
These Closures are really interesting to me .This would be helpful.
<?php
Class Operations{
public function ops($x,$y,$op){
switch ($op){
case 'ADD':return function() use($x,$y){
return $x+$y."<br>";
};
break;
case 'SUB': return function() use ($x,$y){
return $x-$y."<br>";
};
break;
default: return function(){
return "Operation is not supported by class"."<br>";
};
}
}
}
$op = new Operations();
$fn1 = $op->ops(6,7,'ADD');
echo $fn1();
$fn2 = $op->ops(6,2,'SUB');
echo $fn2();
$fn2 = $op->ops(6,7,'MUL');
echo $fn2();
?>
reinaldorock at yahoo dot com dot br ¶
1 year ago
Using closure to encapsulate environment
<?php
$fib = function($n) use(&$fib) {
if($n == 0 || $n == 1) return 1;
return $fib($n - 1) + $fib($n - 2);
};
echo $fib(2) . "\n"; // 2
$lie = $fib;
$fib = function(){die('error');};//rewrite $fib variable
echo $lie(5); // error because $fib is referenced by closure
?>
Alternative Fibonacci implementation using a self called function like javascript to encapsulate references variables.
<?php
$fib = call_user_func(function(){
$fib = function($n) use(&$fib) {
if($n == 0 || $n == 1) return 1;
return $fib($n - 1) + $fib($n - 2);
};
return $fib;
});
echo $fib(2) . "\n";//2
$ok = $fib;
$fib = function(){die('error')};//rewrite $fib variable but don't referenced $fib used by closure
echo $ok(5);//result ok
?>
housni dot yakoob at gmail dot com ¶
3 years ago
If you want to make sure that one of the parameters of your function is a Closure, you can use Type Hinting.
see: http://php.net/manual/en/language.oop5.typehinting.php
Example:
<?php
class TheRoot
{
public function poidh($param) {
echo "TheRoot $param!";
}
}
class Internet
{
# here, $my_closure must be of type object Closure
public function run_my_closure($bar, Closure $my_closure) {
$my_closure($bar);
}
}
$Internet = new Internet();
$Root = new TheRoot();
$Internet->run_my_closure($Root, function($Object) {
$Object->poidh(42);
});
?>
The above code simply yields:
"TheRoot 42!"
NOTE: If you are using namespaces, make sure you give a fully qualified namespace.
print_r() of Internet::run_my_closure's $my_closure
<?php
Closure Object
(
[parameter] => Array
(
[$Object] =>
)
)
?>
var_dump() of Internet::run_my_closure's $my_closure
<?php
object(Closure)#3 (1) {
["parameter"]=>
array(1) {
["$Object"]=>
string(10) ""
}
}
?>
benkuhl at gmail dot com ¶
1 month ago
Beware of scope! $this refers to the class that the function was defined within.
----------- Example #1 - Doesn't work (Notice: Undefined variable: this) -----------
<?php
$callableFunc = function () {
var_dump($this);
};
call_user_func($callableFunc);
?>
----------- Example #2 - Doesn't work (Notice: Undefined variable: this) -----------
<?php
class myClass {
public function execute($func) {
if (is_callable($func)) {
call_user_func($func);
}
}
}
$class = new myClass();
$class->execute(function () {
var_dump($this);
});
?>
----------- Example #3 - Works! -----------
<?php
class myClass {
public function getMyExecutableFunction() {
return function () {
var_dump($this);
};
}
public function execute($func) {
if (is_callable($func)) {
call_user_func($func);
}
}
}
$class = new myClass();
$class->execute($class->getMyExecutableFunction()); //object(myClass)[1]
?>
$this is not available in a static method!
orwellophile at phpblue dot net ¶
11 months ago
You can create a dynamic method with a class, with access to member variables, with a little bit of trickery:
<?
class DynamicFunction {
var $functionPointer;
var $mv = "The Member Variable";
function __construct() {
$this->functionPointer = function($arg) {
return sprintf("I am the default closure, argument is %s\n", $arg);
};
}
function changeFunction($functionSource) {
$functionSource = str_replace('$this', '$_this', $functionSource);
$_this = clone $this;
$f = '$this->functionPointer = function($arg) use ($_this) {' . PHP_EOL;
$f.= $functionSource . PHP_EOL . "};";
eval($f);
}
function __call($method, $args) {
if ( $this->{$method} instanceof Closure ) {
return call_user_func_array($this->{$method},$args);
} else {
throw new Exception("Invalid Function");
}
}
}
if (!empty($argc) && !strcmp(basename($argv[0]), basename(__FILE__))) {
$dfstring1 = 'return sprintf("I am dynamic function 1, argument is %s, member variables is %s\n", $arg, $this->mv);';
$dfstring2 = 'return sprintf("I am dynamic function 2, argument is %s, member variables is %s\n", $arg, $this->mv);';
$df = new DynamicFunction();
$df->changeFunction($dfstring1);
echo $df->functionPointer("Rabbit");
$df->changeFunction($dfstring2);
$df->mv = "A different var";
echo $df->functionPointer("Cow");
};
?>
ldrut ¶
1 year ago
A common way to avoid contaminating Javascript global space with unneeded variables is to move the code into an immediately called anonymous closure.
(function(){ ... })()
The equivalent way to do that in PHP 5.3+ is
call_user_func(function() use(closure-vars){ ... });
simon at generalflows dot com ¶
1 year ago
<?php
/*
* An example showing how to use closures to implement a Python-like decorator
* pattern.
*
* My goal was that you should be able to decorate a function with any
* other function, then call the decorated function directly:
*
* Define function: $foo = function($a, $b, $c, ...) {...}
* Define decorator: $decorator = function($func) {...}
* Decorate it: $foo = $decorator($foo)
* Call it: $foo($a, $b, $c, ...)
*
* This example show an authentication decorator for a service, using a simple
* mock session and mock service.
*/
session_start();
/*
* Define an example decorator. A decorator function should take the form:
* $decorator = function($func) {
* return function() use $func) {
* // Do something, then call the decorated function when needed:
* $args = func_get_args($func);
* call_user_func_array($func, $args);
* // Do something else.
* };
* };
*/
$authorise = function($func) {
return function() use ($func) {
if ($_SESSION['is_authorised'] == true) {
$args = func_get_args($func);
call_user_func_array($func, $args);
}
else {
echo "Access Denied";
}
};
};
/*
* Define a function to be decorated, in this example a mock service that
* need to be authorised.
*/
$service = function($foo) {
echo "Service returns: $foo";
};
/*
* Decorate it. Ensure you replace the origin function reference with the
* decorated function; ie just $authorise($service) won't work, so do
* $service = $authorise($service)
*/
$service = $authorise($service);
/*
* Establish mock authorisation, call the service; should get
* 'Service returns: test 1'.
*/
$_SESSION['is_authorised'] = true;
$service('test 1');
/*
* Remove mock authorisation, call the service; should get 'Access Denied'.
*/
$_SESSION['is_authorised'] = false;
$service('test 2');
?>
Hayley Watson ¶
2 years ago
As an alternative to gabriel's recursive construction, you may instead assign the recursive function to a variable, and use it by reference, thus:
<?php
$fib = function($n)use(&$fib)
{
if($n == 0 || $n == 1) return 1;
return $fib($n - 1) + $fib($n - 2);
};
echo $fib(10);
?>
Hardly a sensible implementation of the Fibonacci sequence, but that's not the point! The point is that the variable needs to be used by reference, not value.
Without the '&', the anonymous function gets the value of $fib at the time the function is being created. But until the function has been created, $fib can't have it as a value! It's not until AFTER the function has been assigned to $fib that $fib can be used to call the function - but by then it's too late to pass its value to the function being created!
Using a reference resolves the dilemma: when called, the anonymous function will use $fib's current value, which will be the anonymous function itself.
At least, it will be if you don't reassign $fib to anything else between creating the function and calling it:
<?php
$fib = function($n)use(&$fib)
{
if($n == 0 || $n == 1) return 1;
return $fib($n - 1) + $fib($n - 2);
};
$lie = $fib;
$fib = function($n)
{
return 100;
};
echo $lie(10); // 200, because $fib(10 - 1) and $fib(10 - 2) both return 100.
?>
Of course, that's true of any variable: if you don't want its value to change, don't change its value.
All the usual scoping rules for variables still apply: a local variable in a function is a different variable from another one with the same name in another function:
<?php
$fib = function($n)use(&$fib)
{
if($n == 0 || $n == 1) return 1;
return $fib($n - 1) + $fib($n - 2);
};
$bark = function($f)
{
$fib = 'cake'; // A totally different variable from the $fib above.
return 2 * $f(5);
};
echo $bark($fib); // 16, twice the fifth Fibonacci number
?>
orls ¶
2 years ago
Watch out when 'importing' variables to a closure's scope -- it's easy to miss / forget that they are actually being *copied* into the closure's scope, rather than just being made available.
So you will need to explicitly pass them in by reference if your closure cares about their contents over time:
<?php
$result = 0;
$one = function()
{ var_dump($result); };
$two = function() use ($result)
{ var_dump($result); };
$three = function() use (&$result)
{ var_dump($result); };
$result++;
$one(); // outputs NULL: $result is not in scope
$two(); // outputs int(0): $result was copied
$three(); // outputs int(1)
?>
Another less trivial example with objects (what I actually tripped up on):
<?php
//set up variable in advance
$myInstance = null;
$broken = function() uses ($myInstance)
{
if(!empty($myInstance)) $myInstance->doSomething();
};
$working = function() uses (&$myInstance)
{
if(!empty($myInstance)) $myInstance->doSomething();
}
//$myInstance might be instantiated, might not be
if(SomeBusinessLogic::worked() == true)
{
$myInstance = new myClass();
}
$broken(); // will never do anything: $myInstance will ALWAYS be null inside this closure.
$working(); // will call doSomething if $myInstance is instantiated
?>
gabriel dot totoliciu at ddsec dot net ¶
2 years ago
If you want to make a recursive closure, you will need to write this:
$some_var1="1";
$some_var2="2";
function($param1, $param2) use ($some_var1, $some_var2)
{
//some code here
call_user_func(__FUNCTION__, $other_param1, $other_param2);
//some code here
}
If you need to pass values by reference you should check out
http://www.php.net/manual/en/function.call-user-func.php
http://www.php.net/manual/en/function.call-user-func-array.php
If you're wondering if $some_var1 and $some_var2 are still visible by using the call_user_func, yes, they are available.
martin dot partel at gmail dot com ¶
2 years ago
$this is currently (PHP 5.3.2) not usable directly with closures.
One can write:
<?php
$self = $this;
function () use ($self) { ... }
?>
but then the private/protected members of $this cannot be used inside the closure. This makes closures much less useful in OO code.
Until this is fixed, one can cheat using reflection:
<?php
class FullAccessWrapper
{
protected $_self;
protected $_refl;
public function __construct($self)
{
$this->_self = $self;
$this->_refl = new ReflectionObject($self);
}
public function __call($method, $args)
{
$mrefl = $this->_refl->getMethod($method);
$mrefl->setAccessible(true);
return $mrefl->invokeArgs($this->_self, $args);
}
public function __set($name, $value)
{
$prefl = $this->_refl->getProperty($name);
$prefl->setAccessible(true);
$prefl->setValue($this->_self, $value);
}
public function __get($name)
{
$prefl = $this->_refl->getProperty($name);
$prefl->setAccessible(true);
return $prefl->getValue($this->_self);
}
public function __isset($name)
{
$value = $this->__get($name);
return isset($value);
}
}
/**
* Usage:
* $self = giveAccess($this);
* function() use ($self) { $self->privateMember... }
*/
function giveAccess($obj)
{
return new FullAccessWrapper($obj);
}
// Example:
class Foo
{
private $x = 3;
private function f()
{
return 15;
}
public function getClosureUsingPrivates()
{
$self = giveAccess($this);
return function () use ($self) {
return $self->x * $self->f();
};
}
}
$foo = new Foo();
$closure = $foo->getClosureUsingPrivates();
echo $closure() . "\n"; // Prints 45 as expected
?>
Hayley Watson ¶
2 years ago
In the code
<?php
function new_counter()
{
$counter = mt_rand();
return function()use(&$counter)
{
return ++$counter;
};
}
$t1 = new_counter();
$t2 = new_counter();
echo $t1(),"\n";
echo $t1(),"\n";
echo $t2(),"\n";
echo $t2(),"\n";
echo $t1(),"\n";
echo $t1(),"\n";
?>
The variable $counter is local to new_counter() and is used by reference by the returned lambda function.
Because $counter is not static, a new variable is created each time new_counter() is called.
But because the lambda function uses a REFERENCE to the $counter variable - and not a new local variable with a copy of the value $counter had when the lambda function was constructed - the $counter variable created when new_counter() ran still exists (because a reference to it still exists).
Every lambda function has a variable reference "hardwired" into it. That variable therefore persists across calls to the lambda function - rather like a static variable.
But that variable is only LOCAL to the new_counter() function that created it. As soon as new_counter() returns, it gives up its reference to $counter. When new_counter() is called again, it gets allocated a NEW $counter variable and gives a reference to THAT variable to the lambda function it constructs.
So the lambda functions in $t1 and $t2 each have their OWN $counter variable - separate from the other's, which persists from one call to the next.
The effect is very similar to declaring and initialising $counter as static within the lambda function - and then it doesn't need to use anything from new_counter() - but you can't initialise a static variable with a function call like mt_rand()!
Pending a decision on what it should mean, $this is not currently (as of 5.3.2) usable within anonymous functions.
There are roughly two positions (plus attempts at compromise), that can be called "early" and "late".
Early: $this refers to the object in whose scope the anonymous function is constructed.
<?php
class Creator
{
public function make_anonymous()
{
return function()
{
return $this;
};
}
}
class Caller
{
public $p;
public function call_anonymous($f)
{
$this->p = $f();
}
}
$alpha = new Creator;
$omega = new Caller;
$omega->call_anonymous($alpha->create_anonymous());
// $omega->p === $alpha
?>
Late: $this refers to the object in whose scope the anonymous function is called.
<?php
class Creator
{
public function make_anonymous()
{
return function()
{
return $this;
};
}
}
class Caller
{
public $p;
public function call_anonymous($f)
{
$this->p = $f();
}
}
$alpha = new Creator;
$omega = new Caller;
$omega->call_anonymous($alpha->create_anonymous());
// $omega->p === $omega
?>
So until this is cleared up, $this won't work in an anonymous function. (Personally, I favour the early method; otherwise the anonymous function - and therefore its Creator - has access to all of the Caller's private properties.)
aaron at afloorabove dot com ¶
3 years ago
Anonymous functions are great for events!
<?php
class Event {
public static $events = array();
public static function bind($event, $callback, $obj = null) {
if (!self::$events[$event]) {
self::$events[$event] = array();
}
self::$events[$event][] = ($obj === null) ? $callback : array($obj, $callback);
}
public static function run($event) {
if (!self::$events[$event]) return;
foreach (self::$events[$event] as $callback) {
if (call_user_func($callback) === false) break;
}
}
}
function hello() {
echo "Hello from function hello()\n";
}
class Foo {
function hello() {
echo "Hello from foo->hello()\n";
}
}
class Bar {
function hello() {
echo "Hello from Bar::hello()\n";
}
}
$foo = new Foo();
// bind a global function to the 'test' event
Event::bind("test", "hello");
// bind an anonymous function
Event::bind("test", function() { echo "Hello from anonymous function\n"; });
// bind an class function on an instance
Event::bind("test", "hello", $foo);
// bind a static class function
Event::bind("test", "Bar::hello");
Event::run("test");
/* Output
Hello from function hello()
Hello from anonymous function
Hello from foo->hello()
Hello from Bar::hello()
*/
?>
ljackson at jjcons dot com ¶
3 years ago
appears kwilson at shuttlebox dot net that you may have just made unintended side effect. Note that adding the global $variable to your test function make the closure function echo second rather than first So the anonymous function works as expected with respect to globals.
<?php
$variable = "first";
$closure = function() {
global $variable;
echo $variable . "\n";
};
$closure();
function test($closure)
{
global $variable; //Note the scope added here
$variable = "second";
$closure();
}
test($closure);
?>
prints:
first
second
tested with php 5.3.1
kwilson at shuttlebox dot net ¶
3 years ago
Using the global keyword apparently pulls variables from the scope where the function was created, not where it is executed.
Example:
<?php
$variable = "first";
$closure = function() {
global $variable;
echo $variable . "\n";
};
$closure();
function test($closure)
{
$variable = "second";
$closure();
}
test($closure);
?>
Will print:
first
first
puskulcu at gmail dot com ¶
3 years ago
hello there!
here is a little code which shows use of the closures as event handlers:
<?php
class Button
{
public $OnBeforeClick;
public $OnAfterClick;
public $Name;
function Button()
{
$this->Name = 'MyButton';
}
public function Click()
{
$this->DoBeforeClick();
echo 'Click!';
$this->DoAfterClick();
}
private function DoBeforeClick()
{
if (isset($this->OnBeforeClick))
{
$Event = $this->OnBeforeClick;
$Event($this);
}
}
private function DoAfterClick()
{
if (isset($this->OnAfterClick))
{
$Event = $this->OnAfterClick;
$Event($this);
}
}
}
//eclipse may warn here about syntax error but no problem, it runs well.
$BeforeClickEventHandler = function($Sender) { echo $Sender->Name . ' (Before Click)'; };
$AfterClickEventHandler = function($Sender) { echo $Sender->Name . ' (After Click)'; };
$MyWidget = new Button();
$MyWidget->OnBeforeClick = $BeforeClickEventHandler;
$MyWidget->OnAfterClick = $AfterClickEventHandler;
$MyWidget->Click();
?>
output:
MyButton (Before Click)
Click!
MyButton (After Click)
i hope you find this useful.
regards.
emre
rob at ubrio dot us ¶
3 years ago
You can always call protected members using the __call() method - similar to how you hack around this in Ruby using send.
<?php
class Fun
{
protected function debug($message)
{
echo "DEBUG: $message\n";
}
public function yield_something($callback)
{
return $callback("Soemthing!!");
}
public function having_fun()
{
$self =& $this;
return $this->yield_something(function($data) use (&$self)
{
$self->debug("Doing stuff to the data");
// do something with $data
$self->debug("Finished doing stuff with the data.");
});
}
// Ah-Ha!
public function __call($method, $args = array())
{
if(is_callable(array($this, $method)))
return call_user_func_array(array($this, $method), $args);
}
}
$fun = new Fun();
echo $fun->having_fun();
?>
mike at blueroot dot co dot uk ¶
3 years ago
To recursively call a closure, use this code.
<?php
$recursive = function () use (&$recursive){
// The function is now available as $recursive
}
?>
This DOES NOT WORK
<?php
$recursive = function () use ($recursive){
// The function is now available as $recursive
}
?>
kukoman at pobox dot sk ¶
3 years ago
be aware of Fatal error: Using $this when not in object context when using in closures
http://wiki.php.net/rfc/closures/removal-of-this
gerard at visei dot nl ¶
3 years ago
The text above the third example tries to explain that anonymous functions can inherit variables from the parent scope, but fails to properly explain how this is done: namely using the "use" keyword in the function definition.
The following page has a much more detailed explanation of closures in PHP 5.3:
http://wiki.php.net/rfc/closures
dave at mausner dot us ¶
3 years ago
Ulderico had it almost right. To avoid confusing the interpreter, when using a simple closure stored in a $variable, you must invoke the nameless function using the function syntax.
<?php
$helloworld = function(){
return "each hello world is different... ".date("His");
};
echo $helloworld( );
?>
Note the empty actual-parameter list in the "echo". NOW IT WORKS.
Anonymous ¶
3 years ago
If you want to check whether you're dealing with a closure specifically and not a string or array callback you can do this:
<?php
$isAClosure = is_callable($thing) && is_object($thing);
?>
tom at r dot je ¶
3 years ago
Unfortunately, you can't get a pointer to a function, the only function pointers are ones which use anonymous functions as they're created.
This wont work:
<?php
$info = phpinfo;
$info();
//or
function foo() {
echo 'bar';
}
$foo = foo;
$foo();
?>
Because of the behavior of $foo(), it will assume $foo is a string, and try to run the function with the name stored in the string.
mcm dot matt at gmail dot com ¶
3 years ago
Example using uasort.
<?php
// Usual method.
function cmp($a, $b) {
return($a > $b);
}
uasort($array, 'cmp');
// New
uasort($array, function($a, $b) {
return($a > $b);
});
?>
a dot schaffhirt at sedna-soft dot de ¶
3 years ago
When using anonymous functions as properties in Classes, note that there are three name scopes: one for constants, one for properties and one for methods. That means, you can use the same name for a constant, for a property and for a method at a time.
Since a property can be also an anonymous function as of PHP 5.3.0, an oddity arises when they share the same name, not meaning that there would be any conflict.
Consider the following example:
<?php
class MyClass {
const member = 1;
public $member;
public function member () {
return "method 'member'";
}
public function __construct () {
$this->member = function () {
return "anonymous function 'member'";
};
}
}
header("Content-Type: text/plain");
$myObj = new MyClass();
var_dump(MyClass::member); // int(1)
var_dump($myObj->member); // object(Closure)#2 (0) {}
var_dump($myObj->member()); // string(15) "method 'member'"
$myMember = $myObj->member;
var_dump($myMember()); // string(27) "anonymous function 'member'"
?>
That means, regular method invocations work like expected and like before. The anonymous function instead, must be retrieved into a variable first (just like a property) and can only then be invoked.
Best regards,
michaelrfairhurst at gmail dot com ¶
5 months ago
While PHPUnit's mocking framework did a pretty good job at keeping a compact
API (more or less) there are times where a mocked return value would be better
handled as a test class property.
<?php
$this->mock = $this->getMock('StdClass');
$_ = $this;
$this->mock->expects($this->once())
->method('getProperty')
->will($this->returnCallback(function() use($_) {
return $_->property;
}));
$this->property = '12345';
$this->assertEquals('12345', $this->mock->getProperty());
// OK (1 Test, 2 Assertions)
?>
BUT:
[[ Just remember the law of demeter, if your mock object is really behaving as _just_
a parameter, you should probably refactor your SUT to just take another parameter
instead of giving it a completely unnecessary dependency. ]]
lennymail at nospam dot gmail dot com ¶
1 year ago
A practical example of anonymous functions could be a clean template system. Here you can completely remove messy HTML from your code and keep everything very readable. The last statement that prints the HTML in the example below resembles LISP or other functional type languages. The closure retains the HTML tag from parent scope(which can be initialized in creative ways) and properly closes it after the function call. Items can either nested or composed within HTML tags.
You can take this idea further and "map and wrap" columns and rows of recordsets with HTML for display. All that is missing now is the CSS to make it attractive in the browser.
Closures can be thought of as a very primitive class that has one "apply" method with some private and public data. Functional programming has been around since the first programming languages in the 1950s.
<?php
function html ($code , $id="", $class=""){
if ($id !== "") $id = " id = \"$id\"" ;
$class = ($class !== "")? " class =\"$class\"":">";
$open = "<$code$id$class";
$close = "</$code>";
return function ($inner = "") use ($open, $close){
return "$open$inner$close";};
}
$layout = array('container','header','pmain','lsidebar','rsidebar','footer');
foreach ($layout as $element)
$$element = html ("div", $element);
$div = html("div", "test");
$bold = html('strong');
$italic = html('i');
$msg= $div($bold($italic("hello from the left sidebar")));
echo $container(
$header(
"This is the header").$pmain(
$lsidebar(
$msg).$rsidebar(
"This is the right sidebar")).$footer(
));
paul at somewhere dot com ¶
2 years ago
I benched instantiating a function and lambda function.
Functions used:
<?php
function data() {
$var = 'hi';
}
$lambda = function() {
$var = 'hi';
}
?>
Bench for instantiating a function:
1.692800000000000082422957 μs
Bench for instantiating Lambda Function:
0.906000000000000027533531 μs
Bench for calling function:
0.7153000000000000468958206 μs
Bench for calling lambda function:
0.6914000000000000145661261 μs
Calling the lambda function and regular function fluctuates between .81 and .65 so they seem to be the same.
Anonymous ¶
2 years ago
use() parameters are early binding - they use the variable's value at the point where the lambda function is declared, rather than the point where the lambda function is called (late binding).
If you want late binding put & before the variable inside use()
<?php
$fn = function () use (&$var) { echo $var; };
?>
Examples:
<?php
// problem 1: this should echo "Canada", not a php notice
$fn = function () use ($country) { echo $country . "\n"; };
$country = 'Canada';
$fn();
// problem 2: this should echo "Canada", not "UnitedStates"
$country = 'UnitedStates';
$fn = function () use ($country) { echo $country . "\n"; };
$country = 'Canada';
$fn();
// problem 3: this should echo "Canada", not "UnitedStates"
$country = (object)array('name' => 'UnitedStates');
$fn = function () use ($country) { echo $country->name . "\n"; };
$country = (object)array('name' => 'Canada');
$fn();
// problem 4: this outputs "Canada". if this outputs "Canada",
// then so should problem 2 above. otherwise this should be
// just as broken as problem 2 and be outputting "UnitedStates"
$country = (object)array('name' => 'UnitedStates');
$fn = function () use ($country) { echo $country->name . "\n"; };
$country->name = 'Canada';
$fn();
?>
see http://bugs.php.net/bug.php?id=50980
(I've just quoted from there, but if you want you can read there the whole feature request)
mike at borft dot student dot utwente dot nl ¶
1 year ago
Since it is possible to assign closures to class variables, it is a shame it is not possible to call them directly. ie. the following does not work:
<?php
class foo {
public test;
public function __construct(){
$this->test = function($a) {
print "$a\n";
};
}
}
$f = new foo();
$f->test();
?>
However, it is possible using the magic __call function:
<?php
class foo {
public test;
public function __construct(){
$this->test = function($a) {
print "$a\n";
};
}
public function __call($method, $args){
if ( $this->{$method} instanceof Closure ) {
return call_user_func_array($this->{$method},$args);
} else {
return parent::__call($method, $args);
}
}
}
$f = new foo();
$f->test();
?>
it
Hope it helps someone ;)
hernan_javier_saab at yahoo dot com ¶
1 year ago
When invoking an anonymous function through throughThroughFunction(), all variables are automatically binded to the inner function. In addition, variables created within the anonymous function are also "binded out" incorporating it to the scope where the anonymous function is being created.
Enjoy!
<?php
class ThroughThrogh {
public $to_export = array();
public $to_import = array();
// we eval() these functions in order to cleanup verbosity. Cleaner this way even though we all heard about the nightmares of eval()
const TX_START_X = 'foreach(get_defined_vars() as $k=>$v){$this->to_export[$k] =&${$k};};';
const TX_START_I = 'foreach($that->to_export as $name => &$variable) ${$name} = &$variable;';
const TX_END_X = 'foreach(get_defined_vars() as $k=>$v){if(!isset($that->to_export[$k])) $that->to_import[$k] =&${$k};};';
const TX_END_I = 'foreach($this->to_import as $name => &$variable) ${$name} = &$variable;';
public function hackClosure($closure, $inject_start, $inject_end) {
$reflection = new ReflectionFunction($closure);
$tmp = $reflection->getParameters();
$args = array('$that');
foreach ($tmp as $a)
array_push($args, '$' . $a->getName() . ($a->isDefaultValueAvailable() ? '=\'' . $a->getDefaultValue() . '\'' : ''));
$file = new SplFileObject($reflection->getFileName());
$file->seek($reflection->getStartLine() - 1);
$code = '';
while ($file->key() < $reflection->getEndLine()) {
$code .= $file->current();
$file->next();
}
$start = strpos($code, '{') + 1;
$end = strrpos($code, '}');
return create_function(implode(', ', $args), "$inject_start;" . substr($code, $start, $end - $start) . "$inject_end;");
}
//here is where we invoke the function
public function throughThroughFunction($that, $callback){
$this->to_export["that"] = $that;
$inject_start = self::TX_START_I;// potentially you can add setup code in here
$inject_end = self::TX_END_X;// potentially you can add cleanup code in here
$callback = $this->hackClosure($callback, $inject_start, $inject_end);
call_user_func($callback, $that);
}
//user test
public function test(){
$outscope = "Source External Scope: test... not modified if seen at end of function\n";
$this->test = "Source External Scope: object attribute from outside anonymous function\n";
eval($this::TX_START_X); //required to export all variables from scope
$this->throughThroughFunction($this, function(){
echo "Source Anonymous Function\n";
echo $outscope;
echo $that->test;
$that->test = "Source Anonymous Function Scope: wow! Object attribute modified from inside anonymous function\n";
$outscope = "Source Anonymous Function Scope: yey! Variable Modified from the scope of an anonymous function!\n";
$from_anonymous_function = "Source Anonymous Function Scope: No way! How did you do that?\n";
} );
eval($this::TX_END_I); //require to bring newly created variables from anonymous function into current scope
echo "\nSource External Scope\n";
echo $from_anonymous_function;
echo $outscope;
echo $this->test;
}
}
$demo = new ThroughThrogh();
$demo->test();
?>
Output
Source Anonymous Function
Source External Scope: test... not modified if seen at end of function
Source External Scope: object attribute from outside anonymous function
Source External Scope
Source Anonymous Function Scope: No way! How did you do that?
Source Anonymous Function Scope: yey! Variable Modified from the scope of an anonymous function!
Source Anonymous Function Scope: wow! Object attribute modified from inside anonymous function
muratyaman at gmail dot com ¶
4 months ago
simple calculator.
<?php
$inputs = array(2,'+',3,'*',3);
$operators = array();
$operators['+'] = function ($i1, $i2) { echo "$i1 + $i2 => "; return $i1 + $i2; };
$operators['-'] = function ($i1, $i2) { echo "$i1 - $i2 => "; return $i1 - $i2; };
$operators['*'] = function ($i1, $i2) { echo "$i1 * $i2 => "; return $i1 * $i2; };
$operators['/'] = function ($i1, $i2) { echo "$i1 / $i2 => "; return $i1 / $i2; };
$operator = NULL;
$result = 0.0;
foreach ($inputs as $input) {
if ( array_key_exists ($input, $operators) ) {
$operator = $operators[$input];
} else {
if ( is_null($operator) ) {
$result = $input;//first input
} else {
$result = $operator ($result, $input);
echo $result . "\n";
}
}
}
echo $result;
?>