Weakref
PHP Manual

The WeakMap class

(PECL weakref >= 0.2.0)

简介

类摘要

WeakMap implements Countable , ArrayAccess , Iterator {
/* 方法 */
public __construct ( void )
public int count ( void )
public mixed current ( void )
public object key ( void )
public void next ( void )
public bool offsetExists ( object $object )
public mixed offsetGet ( object $object )
public void offsetSet ( object $object , mixed $value )
public void offsetUnset ( object $object )
public void rewind ( void )
public bool valid ( void )
}

范例

Example #1 Weakmap usage example

<?php
$wm 
= new WeakMap();

$o = new StdClass;

class 
{
    public function 
__destruct() {
        echo 
"Dead!\n";
    }
}

$wm[$o] = new A;

var_dump(count($wm));
echo 
"Unsetting..\n";
unset(
$o);
echo 
"Done\n";
var_dump(count($wm));

以上例程会输出:

int(1)
Unsetting..
Dead!
Done
int(0)

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Weakref
PHP Manual