README.md

WHAT?

<?php

function machine_forget(&$data) {
    $data = null;
}

$answer = 42;
var_dump((string)$answer);
machine_forget($answer);
var_dump((string)$answer);

// shhh no spoilers
eval(base64_decode('CmNsYXNzIHpvbWJpZQp7CiAgICBwcm90ZWN0ZWQgJHZhbDsKICAgIHB1YmxpYyBmdW5jdGlvbiBfX2NvbnN0cnVjdCgkdmFsKQogICAgewogICAgICAgICR0aGlzLT52YWwgPSAkdmFsOwogICAgfQoKICAgIHB1YmxpYyBmdW5jdGlvbiBfX2Rlc3RydWN0KCkKICAgIHsKICAgICAgICAkdGhpcy0+dmVzc2VsID0gJHRoaXM7CiAgICB9CgogICAgcHVibGljIGZ1bmN0aW9uIF9fdG9TdHJpbmcoKQogICAgewogICAgICAgIHJldHVybiAkdGhpcy0+dmFsOwogICAgfQp9CgokYW5zd2VyID0gbmV3IHpvbWJpZSgiNDIiKTsKJGFuc3dlci0+dmVzc2VsID0gJiRhbnN3ZXI7'));

var_dump((string)$answer);
machine_forget($answer);
var_dump((string)$answer);

// DID NOT FORGET

Ouput is:

string(2) "42"
string(0) ""
string(2) "42"
string(2) "42"

In reply to https://gist.github.com/igorw/4485603500b4bf6511e1

Mind blown.

awesome @scoates 👍