<?php
function test_1() {
    static $v = 0;
    ++$v;
    echo "Outer function increments \$v to $v\n";
    $f = function() use($v) {
        echo "Inner function reckons \$v is $v\n";
    };
    return $f;
}

$f = test_1(); $f();
$f = test_1(); $f();

function test_2() {
    static $v = 0;
    $f = function() use($v) {
        echo "Inner function reckons \$v is $v\n";
    };
    ++$v;
    echo "Outer function increments \$v to $v\n";
    return $f;
}

$f = test_2(); $f();
$f = test_2(); $f();

function test_3() {
    static $v = "";
    $v .= 'b';
    echo "Outer function catenates 'b' onto \$v to give $v\n";
    $f = function() use($v) {
        echo "Inner function reckons \$v is $v\n";
    };
    $v .= 'a';
    echo "Outer function catenates 'a' onto \$v to give $v\n";
    return $f;
}
$f = test_3(); $f();
$f = test_3(); $f();
?>