PHP Manual
WeakRef
Constructs a new weak reference

Weakref::__construct

(PECL weakref >= 0.1.0)

Weakref::__construct — Constructs a new weak reference

说明

public Weakref::__construct ( object $object )

Constructs a new weak reference.

参数

object: The object to reference.

返回值

没有返回值。

范例

Example #1 Weakref::__construct() 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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