Weakref::valid

(PECL weakref >= 0.1.0)

Weakref::validComprueba si el objeto referenciado aún existe

Descripción

public bool Weakref::valid ( void )

Comprueba si el objeto referenciado aún existe.

Parámetros

Esta función no tiene parámetros.

Valores devueltos

Devuelve TRUE si el objeto aún existe y es accesible mediante Weakref::get(), o FALSE en caso contrario.

Ver también

  • Weakref::get() - Devuelve el objeto apuntado por una referencia débil

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User Contributed Notes 1 note

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d dot negrier at nospam dot thecodingmachine dot com
21 days ago
Beware that the "valid()" method should not be used to check the availability of an object before calling "get()". Indeed, the garbage collector might be triggered between the call to "valid()" and the call to "get()".

<?php

if ($weakRef->valid()) { // Returns true because the object is not yet garbage collected
    // If you are not lucky, the garbage collector might be triggered here
   
$obj = $weakRef->get(); // Returns null
   
$obj->doSomeStuff(); // Boom!
}
?>

So instead, you should always call "get()" directly:

<?php
$obj
= $weakRef->get();
if (
$obj !== null) {
   
$obj->doSomeStuff(); // This is 100% accurate
}
?>

Generally speaking, the "valid()" method is tricky because a call to it might return true and the next call might return false (you never know when the garbage collector will be trigerred). However, testing for invalidity works reliably.

<?php
if ($weakRef->valid()) {
   
// At this point, you are not sure that the object is still there (garbage collector might have collected it)
}

if (!
$weakRef->valid()) {
   
// At this point, you are sure the object is gone.
}
?>
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