Re: [RFC] Context Managers

Hi On 1/15/26 19:38, Volker Dusch wrote:

a function is already a reasonable scope

That - together with the other points you raised - made me realize one thing: In contrast to block scoping, the main purpose of “Context Managers” is *not* managing arbitrary variables in the current scope in combination with existing control structures. Instead it is just managing a single variable in a reasonably *self-contained* fashion, with other variables just needing to “exist”. It could therefore also just be a regular function taking a callback, as is already done in userland, e.g. with Laravel's DB::transaction() helper. I believe something like this would be equivalent to the RFC:

    function using(
        callable $runInContext,
        ContextManager ...$managers
    ): void {
        $contexts = [];
        foreach ($managers as $manager) {
            $contexts[] = $manager->enterContext();
        }

        try {
            $runInContext(...$contexts);
            foreach (array_reverse($managers) as $manager) {
                $manager->exitContext();
            }
        } catch (Throwable $e) {
            foreach (array_reverse($managers) as $manager) {
                if ($manager->exitContext($e) === true) {
                    $e = null;
                }
            }
            if ($e !== null) {
                throw $e;
            }
        }
    }

This would completely side-steps the “break to exit” question, since a return will just work. It also avoids introducing new keywords, it just requires a new function in the global namespace. I understand that using variables from the current scope in a Closure is currently not particularly convenient, particularly when they need to be changed. However this is something that can be solved in a generic fashion, for example inspired by the C++ lambda syntax:

    // Captures everything by value and $result by reference.
    function ($context) use (*, &$result) { }

    // Captures everything by reference.
    function ($context) use (&*) { }

which would also be useful in other situations. Best regards Tim Düsterhus