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    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

    up
    -42
    Sandor Toth
    5 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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