Re: Previous discussions about generics syntax only?

On Wed, Oct 18, 2023, at 11:01 AM, Alex Wells wrote: > On Tue, Oct 17, 2023 at 10:40 PM Rowan Tommins <rowan.collins@gmail.com> > wrote: > > Using the same syntax for type information that is guaranteed to be true >> (existing run-time checks) and type information that is "advisory only" >> (new checks for optional static analysis) means users can no longer have >> confidence in that type information. > > > If "syntax only" solution was temporary then warning users through some > kind of opt-in mechanism (like with strict_types=1) may be enough - that > way users will know that generics type information is "advisory only" and > that this might change in the future. In some other languages (Kotlin) > there are opt-in mechanism for experimental features - ones that are > possibly incomplete, unstable or non-final, and it's working quite well for > them. > > On the other hand, I can see a "third way": if the problem with current >> static analysis conventions is that they have to be parsed out of a >> string-based docblock, we can provide *dedicated* syntax, without >> unifying it with the standard type syntax. For instance, some of the >> earlier discussions around introducing attributes suggested reflection >> expose the AST of the attributes arguments, rather than the resolved >> expressions, allowing them to act a bit like Rust's "hygienic macros". >> If that was added as an optional mode, you might be able to do something >> like this: >> > > The community has just now decided on the PHPDoc syntax for generics, has > just started widely adopting them in packages and has just got first-party > support from PHPStorm. I doubt that migrating to yet another temporary > solution (one that still doesn't address all of the concerns) is a good > idea right now. That's fine for systems already invested in building and maintaining a docblock parser. But that's a not-small lift. In contrast, I built a serialization library that relies heavily on attributes. Most are opt-in, but for array properties, you really have to use one of #[SequenceField(Type::class)] or #[DictionaryField(Type::class, keyType: KeyType::String] so the system knows if it's a sequence or dictionary, and what the types are. It just can't do most things without that knowledge. I didn't want to add custom, proprietary attributes for that, but it was better than either writing a docblock parser myself or adding and figuring out how to use a 3rd party dependency. I am not happy with this solution. If there was some universally recognized #[Array(Type::int)] (for a list of ints) or #[Array(Type::string, Foo::class)] (for a string-keyed dict of Foo objects), I could easily access through the reflection/attribute API instead. That would make life a lot easier for both me and anyone using my library, as they wouldn't need to specify that information twice in two different forms. It would still not be a "real syntax", but it would make the de facto convention more accessible to projects other than PHPStan and Psalm. That said, I agree that such an attribute-based convention, while it would be superior to the docblock approach in almost every way, would still not belong in the language itself. Save the language itself for if/when we figure out for-reals generics. That would be a project for PHPStan, Psalm, and PHPStorm to collaborate on in user-space. (FIG would be happy to host such a discussion if they were interested, but I don't know if they're at all interested.) --Larry Garfield