PHP Closure Using external variables


It is possible, inside a closure, to use an external variable with the special keyword use. For instance:


$quantity = 1;

$calculator = function($number) use($quantity) {
    return $number + $quantity;

var_dump($calculator(2)); // Shows "3"

You can go further by creating "dynamic" closures. It is possible to create a function that returns a specific calculator, depending on the quantity you want to add. For example:


function createCalculator($quantity) {
    return function($number) use($quantity) {
        return $number + $quantity;

$calculator1 = createCalculator(1);
$calculator2 = createCalculator(2);

var_dump($calculator1(2)); // Shows "3"
var_dump($calculator2(2)); // Shows "4"