WeakReference 类

(PHP 7 >= 7.4.0, PHP 8)

简介

弱引用可以指向一个对象,并且不阻止对象的销毁。可以实现具有对象结构的缓存。

弱引用类不能序列化。

类摘要

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

弱引用示例

示例 #1 弱引用的基础用法

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

以上示例的输出类似于:

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

目录

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User Contributed Notes 1 note

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-42
Sandor Toth
4 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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