The WeakReference class

(PHP 7 >= 7.4.0, PHP 8)

Introduzione

Weak references allow the programmer to retain a reference to an object which does not prevent the object from being destroyed. They are useful for implementing cache like structures.

WeakReferences cannot be serialized.

Sommario della classe

final class WeakReference {
/* Metodi */
public __construct()
public static create(object $object): WeakReference
public get(): ?object
}

WeakReference Examples

Example #1 Basic WeakReference Usage

<?php
$obj 
= new stdClass;
$weakref WeakReference::create($obj);
var_dump($weakref->get());
unset(
$obj);
var_dump($weakref->get());
?>

Il precedente esempio visualizzerà qualcosa simile a:

object(stdClass)#1 (0) {
}
NULL

Indice dei contenuti

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User Contributed Notes 1 note

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-31
Sandor Toth
2 years ago
You might consider to use WeakReference in your Container class. Don't forget to create the object into a variable and pass the variable to WeakReference::create() otherwise you going to ->get() null.

Consider as wrong solution, which returns null
<?php
/**
* @return App
*/
public static function app() : App
{
    if (!static::
$app) {
       static::
$app = WeakReference::create(new App());
    }

    return static::
$app->get();
}
?>

Consider as GOOD solution, which returns App instance
<?php
/**
* @return App
*/
public static function app() : App
{
    if (!static::
$app) {
      
$app = new App();
       static::
$app = WeakReference::create($app);
    }

    return static::
$app->get();
}
?>
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