(PECL ds >= 1.0.0)
Ds\Deque::apply — Updates all values by applying a callback function to each value
    Updates all values by applying a callback function to
    each value in the deque.
  
callback
A callable to apply to each value in the deque.
The callback should return what the value should be replaced by.
Aucune valeur n'est retournée.
Exemple #1 Ds\Deque::apply() example
<?php
$deque = new \Ds\Deque([1, 2, 3]);
$deque->apply(function($value) { return $value * 2; });
print_r($deque);
?>
Résultat de l'exemple ci-dessus est similaire à :
Ds\Deque Object
(
    [0] => 2
    [1] => 4
    [2] => 6
)