Re: RFC: Support Closures in constant expressions

On Mon, Nov 4, 2024, at 6:06 AM, Tim Düsterhus wrote: > Hi > > Am 2024-10-31 07:16, schrieb Larry Garfield: >> Hm. It would never occur to me to use a function for a non-class >> constant in the first place, so I don't know. :-) Frankly I can't >> recall the last time I used a non-class constant period. :-) >> >> That said, PHP consts are already a bit squishy, and auto-capture is >> always by value. That wouldn't give us a loophole? > > Here's another brainteaser: > > function foo( > string $bar, > Closure $baz = static fn () => $bar, > ) { > var_dump($baz()); > } > > foo('captured'); > > What would you expect the semantics of that script to be? My expectation is that it's confusing, and therefore we should simply disallow it. Which roughly translates to detecting if a closure tries to use an unbound variable statically. Which is probably more difficult than I make it sound. :-) >> If it cannot reasonably be done now, but is possible, that should be >> listed in future scope with roughly what it would take for a follow-up >> to do. (And then we can argue if it should just be done now, with more >> information as to how much work that is.) > > I have added an entry to the “Future Scope” section. See also my reply > to Alex. > > Best regards > Tim Düsterhus Thanks. Can you include what the implementation challenges are for the future-scope items, to explain why they're being punted to later rather than addressed now? (As there seems clear interest in having all of them.) --Larry Garfield