Re: Idea: Implicit inheriting function argument & return type-hint

> On 9 Mar 2024, at 21:27, Christian Schneider <cschneid@cschneid.com> wrote: > Am 09.03.2024 um 08:18 schrieb Marc <marc@mabe.berlin>: >> As the pseudo type mixed exists since PHP 8.0, which is >> already out-of-date, I have the feeling it would be better to force people to explicitly write >> mixed to widen the type of an overwritten function and let "no >> type" inherit the argument and return type of the parent. >> >> Example: >> >> class A { >> public function typed(int $var): int { return $var; } >> public function untyped($var) { return $var; } // implicit mixed as no overwrite >> } >> class B extends A { >> public function typed($var) { return $var; } // implicit int as inherited from >> overwritten function >> } > > This sounds like a bad idea to me as I cannot look at the function definition in class B and > determine what the type of $var is. > On top of that: If the type of $var in A is changed then it would automatically also change in > B. While this seems convenient it could also break B in subtle ways as the function suddenly gets > different types than expected. > > Regards, > - Chris I guess my discussion with Larry was at least part of what you're referring to. The proposal here would introduce the same problem as we discussed on the other RFC: inconsistency with what people are used to elsewhere in the language (eg untyped properties). It also means that existing code would have the complete opposite effect to previously, making it a huge BC break. You'd likely have to have two stages: deprecate and then remove use of untyped parameters, and then reintroduce untyped to mean "inherited" type, which still suffers from the issues Christian pointed out. I could get behind the "first half" of that process: making a type required (ie deprecating type-less parameters/properties) but I doubt there's enough support for that to pass a vote. Cheers Stephen