Closure

Closure.php

<?php
/** example */
$text = function (string $text) {
    return $text;
};

$text('hello'); //return hello

$text = 'sum = ';
//в use можно передать несколько переменных function() use($var1, $var2) { }
$sum = function ($a, $b) use ($text) {
    $sum = $a + $b;

    return $text . $sum;
};
$sum(2, 3); //return sum = 5
$text = 'new text';
$sum(3, 3); //return sum = 6