Weakref
PHP Manual

The WeakRef class

(PECL weakref >= 0.1.0)

简介

The WeakRef class provides a gateway to objects without preventing the garbage collector from freeing those objects. It also provides a way to turn a weak reference into a strong one.

类摘要

WeakRef {
/* 方法 */
public Weakref::__construct ( object $object )
public bool Weakref::acquire ( void )
public object Weakref::get ( void )
public bool Weakref::release ( void )
public bool Weakref::valid ( void )
}

范例

Example #1 WeakRef usage example

<?php
class MyClass {
    public function __destruct() {
        echo "Destroying object!\n";
    }
}

$o1 = new MyClass;

$r1 = new WeakRef($o1);

if ($r1->valid()) {
    echo "Object still exists!\n";
    var_dump($r1->get());
} else {
    echo "Object is dead!\n";
}

unset($o1);

if ($r1->valid()) {
    echo "Object still exists!\n";
    var_dump($r1->get());
} else {
    echo "Object is dead!\n";
}
?>

以上例程会输出：

Object still exists!
object(MyClass)#1 (0) {
}
Destroying object!
Object is dead!

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Weakref
PHP Manual