On Sat, Jun 11, 2022 at 11:14 PM Rowan Tommins <rowan.coll...@gmail.com> wrote:
> On 09/06/2022 17:34, Larry Garfield wrote: > > Last year, Nuno Maduro and I put together an RFC for combining the > multi-line capabilities of long-closures with the auto-capture compactness > of short-closures ... Arnaud Le Blanc has now picked up the flag with an > improved implementation ... The RFC has therefore been overhauled > accordingly and is now ready for consideration. > > > > https://wiki.php.net/rfc/auto-capture-closure > > > They may sound like the same thing, but to me "short closure syntax" > (and a lot of the current RFC) implies that the new syntax is better for > nearly all closures, and that once it is introduced, the old syntax > would only really be there for compatibility - similar to how the [] > syntax replaces array() and list(). If that is the aim, it's not enough > to assert that "the majority" of closures are very short; the syntax > should stand up even when used for, say, a middleware handler in a > micro-framework. As such, I think we need additional features to opt > back out of capturing, and explicitly mark function- or block-scoped > variables. > The RFC does mention that the existing Anonymous Function Syntax remains untouched and will not be deprecated. Whether the new syntax is better for nearly all closures will be a personal choice. If the new syntax doesn't suit, say, a middleware handler, then we still can: - reach for the old syntax - use invocable classes - call another method or function which creates a brand new scope and then returns a function/callable. > > On the other hand, "auto-capturing" could be seen as a feature in its > own right; something that users will opt into when it makes sense, while > continuing to use explicit capture in others. If that is the aim, the > proposed syntax is decidedly sub-optimal: to a new user, there is no > obvious reason why "fn" and "function" should imply different semantics, > or which one is which. A dedicated syntax such as use(*) or use(...) > would be much clearer. We could even separately propose that "fn" and > "function" be interchangeable everywhere, allowing combinations such as > "fn() use(...) { return $x; }" and "function() => $x;" > The previous discussions talked about use(*) or use(...) and most people I know that would love this RFC to pass would also dislike that alternative. It does not have the greatest asset for short closure: aesthetics. Maybe my personal bubble is not statistically relevant, but this is where PHP Internals is lacking on surveying actual users of the language to help on such matters. All I can say is that use(*) is not a replacement for the RFC. > > To go back to the point about variable scope: right now, if you're in a > function, all variables are scoped to that function. With a tiny handful > of exceptions (e.g. superglobals), access to variables from any other > scope is always explicit - via parameters, "global", "use", "$this", and > so on. If we think that should change, we should make that decision > explicitly, not treat it as a side-effect of syntax. > Any attempt to make it explicit defeats the purpose of the RFC. The auto-capturing means we don't have to write awkward code to access variables. The only way we have to avoid awkward syntax (such as use ($var1, $var2)) is to declare an entire new invocable class and send the parameters via the constructor. When many variables are involved, that may still be a great option, but doing that just for 1 variable and 2 lines is quite... sad. When I think of new accessors for this particular case, they would either be innovative or verbose. If they are verbose, we already have a syntax for that. If they are innovative, it would be an awkward out-of-place situation that doesn't happen elsewhere in the language. Or I lack the imagination to see a different result. Ultimately, I see fn() as "an opt-in to not create a separate scope for a function". PHP has several language constructs that may or may not create a separate scope. Delimite Scope: function, method, class, procedural file Shared scope: if, for, foreach, include, require and fn > Regards, > > -- > Rowan Tommins > [IMSoP] > > -- > PHP Internals - PHP Runtime Development Mailing List > To unsubscribe, visit: https://www.php.net/unsub.php > > -- Marco Aurélio Deleu
