php[world] 2019 — 25 years of PHP

The WeakReference class

(PHP 7 >= 7.4.0)

Introduction

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.

Note:

The class WeakReference is not to be confused with the class WeakRef of the Weakref extension.

WeakReferences cannot be serialized.

Class synopsis

WeakReference {
/* Methods */
public __construct ( void )
public static create ( object $referent ) : WeakReference
public get ( void ) : ?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());
?>

The above example will output something similar to:

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

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