La clase Closure

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

Introducción

Clase empleada para representar funciones anónimas.

Las funciones anónimas producían objetos de este tipo. Esta clase tiene métodos que permiten más control sobre las funciones anónimas después de haber sido creadas.

Además de los métodos listados aquí, esta clase también posse un método __invoke. Está por consistencia con otras clases que implementan la llamada mágica, ya que este método no se usa para llamar a la función.

Sinopsis de la Clase

final class Closure {

/* Métodos */

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

}

Tabla de contenidos

Closure::__construct — Constructor que anula la instanciación
Closure::bind — Duplicar un cierre con un objeto vinculado y ámbito de clase especificados
Closure::bindTo — Duplicar el cierre con un objeto vinculado y ámbito de clase nuevos
Closure::call — Vincula y llama al cierre
Closure::fromCallable — Convierte un 'callable' en un cierre

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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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