Re: [RFC] Short Closures 2, aka auto-capture take 3

On 14/06/2022 12:18, Arnaud Le Blanc wrote:

- The closure mutates a value accessed through a captured variable. Mutable values include objects and resources, but NOT scalars or arrays (since they are copy-on-write).

It's not something that is used very often, so is often forgotten or ignored, but there is technically an edge case where arrays are mutable: they can contain references, and the references remain "live" even when the array itself is passed by value. So although unlikely, it is possible for a by-value closure to over-write variables in other scopes: https://3v4l.org/dPZlI // plain variable $a = 42; // array containing a reference $b = [

    'a' => &$a

]; // capture the array by-value $f = function() use($b) {

    // update the reference from inside the closure
    $b['a'] = 69;

}; // call it $f(); // observe that both the array and the plain variable now have the new value var_dump($a, $b); -- Rowan Tommins [IMSoP]