La classe Closure

(PHP 5 >= 5.3.0, PHP 7, PHP 8)

Introduzione

Classe usata per rappresentare funzioni anonime.

Le funzioni anonime producono oggetti di questo tipo. Questa classe contiene dei metodi che consentono un ulteriore controllo della funzione anonima dopo che è stata creata.

Oltre ai metodi qui elencati, questa classe ha anche un metodo __invoke. Questo è stato implementato per dare coerenza con le altre classi che implementano le chiamate magiche, dato che questo metodo non viene usato per chiamare la funzione.

Sommario della classe

final class Closure {

/* Metodi */

private __construct()

public static bind(Closure $closure, ?object $newThis, object|string|null $newScope = "static"): ?Closure

public bindTo(?object $newThis, object|string|null $newScope = "static"): ?Closure

public call(object $newThis, mixed ...$args): mixed

public static fromCallable(callable $callback): Closure

}

Indice dei contenuti

Closure::__construct — Costruttore che non permette l'istanziazione
Closure::bind — Duplicates a closure with a specific bound object and class scope
Closure::bindTo — Duplica la closure con una nuova associazione all'oggetto e alla visibilità della classe
Closure::call — Binds and calls the closure
Closure::fromCallable — Converts a callable into a closure

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User Contributed Notes 4 notes

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453

chuck at bajax dot us ¶

9 years ago

This caused me some confusion a while back when I was still learning what closures were and how to use them, but what is referred to as a closure in PHP isn't the same thing as what they call closures in other languages (E.G. JavaScript).

In JavaScript, a closure can be thought of as a scope, when you define a function, it silently inherits the scope it's defined in, which is called its closure, and it retains that no matter where it's used.  It's possible for multiple functions to share the same closure, and they can have access to multiple closures as long as they are within their accessible scope.

In PHP,  a closure is a callable class, to which you've bound your parameters manually.

It's a slight distinction but one I feel bears mentioning.

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107

joe dot scylla at gmail dot com ¶

8 years ago

Small little trick. You can use a closures in itself via reference.

Example to delete a directory with all subdirectories and files:

<?php
$deleteDirectory = null;
$deleteDirectory = function($path) use (&$deleteDirectory) {
    $resource = opendir($path);
    while (($item = readdir($resource)) !== false) {
        if ($item !== "." && $item !== "..") {
            if (is_dir($path . "/" . $item)) {
                $deleteDirectory($path . "/" . $item);
            } else {
                unlink($path . "/" . $item);
            }
        }
    }
    closedir($resource);
    rmdir($path);
};
$deleteDirectory("path/to/directoy");
?>

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luk4z_7 at hotmail dot com ¶

9 years ago

Scope
A closure encapsulates its scope, meaning that it has no access to the scope in which it is defined or executed. It is, however, possible to inherit variables from the parent scope (where the closure is defined) into the closure with the use keyword:

function createGreeter($who) {
              return function() use ($who) {
                  echo "Hello $who";
              };
}

$greeter = createGreeter("World");
$greeter(); // Hello World

This inherits the variables by-value, that is, a copy is made available inside the closure using its original name.
font: Zend Certification Study Guide.

down

info at ensostudio dot ru ¶

2 years ago

compare closures:
<?php 
(string) new ReflectionFunction($fn) === (string) new ReflectionFunction($fn2)
?>

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