Re: [RFC] [Under Discussion] Auto-implement Stringable for string backed enums

Hi Benjamin and Derick, I'm replying to both of you because I see some things in common in your comments. >https://wiki.php.net/rfc/auto-implement_stringable_for_string_backed_enums I would prefer if this was an explicit opt-in to have a __toString on a > backed enum. Maybe a special trait for enums that has the implementation, > so that a custom __toString cannot be implemented or a new syntax "enum Foo > : Stringable". > We can make this opt-in by simply allowing user-land to implement Stringable. This is a different solution to the problem the RFC tries to solve and I would also personally be fine with. I would then *not* try to limit which implementation of it is allowed by the engine. Instead, I would give all powers to user-land to decide on their own what makes sense for their use case. As a general principle, I believe that empowering user-land is always a win vs trying to "save them from themselves", as if we knew better than them what they want to achieve, and especially how. > My concern is that auto implementing __toString, will lead to decreasing > type safety of enums in weak typing mode, since they get auto-casted to > string when passed to a function accepting strings. This effectively adds > more type juggling cases. > I don't share this concern: if an API accepts a string and the engine can provide a string, let it do so. There is nothing inherently dangerous in doing so. But we don't need to agree on that if the proposal above makes sense to everybody :) > The example in the RFC about attributes accepting strings or Enums can be > solved by union types on the side of the library developers, it doesn't > need to be magically implemented by the engine. > I extensively explain in the RFC why this should not be on the side of lib authors, but on the side of end-users. Please double check and let me know your thoughts. > I don't consider "use strict mode" a good argument to avoid this problem, > because that has other downsides such as overcasting. > I'm 100% aligned with that. 2. It is not implemented for all enum types, only for string backed ones. > This change would now make different classes of enums, without them being > differently inherited classes. > This would also be solved by allowing user-land to implement Stringable on *all* kind of enums. Would that make sense to you? > 3. The main use case seems to be to prevent having to type ->value, which > would otherwise indicate reliably whether an enum is used as string > argument. > Yep, that's a "strict mode" approach and this RFC mostly applies to non-strict mode. There are also cases where using "->value" is just not possible. I mention attributes in the RFC, but we also have a case in Symfony where defining service definitions in yaml doesn't work with enums because there is no way to express the "->value" part. If that's the consensus, I'm fine updating the RFC to turn the vote into whether "allowing user-land to implement Stringable on any kind of enums" is desired or not. Nicolas