JuniorTheoryCommon

What does the program print?

PHP

<?php

$factor = 2;
$scale = function (int $n) use ($factor) {
    return $n * $factor;
};
$factor = 10;
echo $scale(3), ' ', $factor, "\n";

6 10

Expecting 30, as if the closure read $factor at call time: use ($factor) copies the value when the closure is created, so later assignments are not seen.
Expecting use ($factor) to be extra parameters the call fills in: the list is filled once, when the closure is created, and the call passes only $n.

JuniorTheoryCommon

PHP

<?php

$factor = 2;
$scale = function (int $n) use ($factor) {
    return $n * $factor;
};
$factor = 10;
echo $scale(3), ' ', $factor, "\n";

6 10

Expecting 30, as if the closure read $factor at call time: use ($factor) copies the value when the closure is created, so later assignments are not seen.
Expecting use ($factor) to be extra parameters the call fills in: the list is filled once, when the closure is created, and the call passes only $n.