WeakReference 类

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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

WeakReference {
/* 方法 */
public __construct ( )
public static create ( object $object ) : WeakReference
public get ( ) : object|null
}

弱引用示例

Example #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());
?>

以上例程的输出类似于：

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

Table of Contents

User Contributed Notes

Sandor Toth 11-Dec-2019 04:09
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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