Weakref::valid

(PECL weakref >= 0.1.0)

Weakref::validVérifie si l'objet référencé existe toujours

Description

public bool Weakref::valid ( void )

Vérifie si l'objet référencé existe toujours.

Liste de paramètres

Cette fonction ne contient aucun paramètre.

Valeurs de retour

Retourne TRUE si l'objet existe toujours et ainsi, est toujours accessibe via la méthode Weakref::get(), FALSE sinon.

Voir aussi

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User Contributed Notes 1 note

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d dot negrier at nospam dot thecodingmachine dot com
19 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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