PHP マニュアル: Updates all values by applying a callback function to each value

public void Ds\Vector::apply(callable $callback)

Updates all values by applying a callback function to each value in the vector.

callback

mixed callback(mixed $value)

A callable to apply to each value in the vector.

The callback should return what the value should be replaced by.

値を返しません。

例1 Ds\Vector::apply example

<?php
$vector = new \Ds\Vector([1, 2, 3]);
$vector->apply(function($value) { return $value * 2; });

print_r($vector);
?>

上の例の出力は、たとえば以下のようになります。

Ds\Vector Object
(
    [0] => 2
    [1] => 4
    [2] => 6
)