Hey Rokas, The idea of declaring an enum `abstract` is potentially worth exploring (I'm not convinced, but go for it), but beware that removing the implicit `final` from ENUMs is a BC break, since it breaks the assumption that an ENUM is a sealed type.
If you design a proposal now, you need to consider that `final` as the implicit default is an existing contract that really enables ENUM usage. Marco Pivetta https://mastodon.social/@ocramius https://ocramius.github.io/ On Wed, 29 Mar 2023 at 11:05, Rokas Šleinius <rave...@gmail.com> wrote: > > to restrict options within a certain range. > Okay that's an aspect of enums that I never gave much thought to, but > you're completely right. > > However to be explicit about that aspect of functionality one would > then have to also be > allowed to define final enums. > > That way you still have both options - to restrict the option set, but > to also allow adding > custom ones while benefiting from other enum advantages. > > Thus, rfc idea seems to be: > * enums should be able to extend other enums; > * abstract enums; > * enums allowed to implement interfaces; > * final enums (NEW!) > > > > > BackedEnum&MyCustomBehaviorInt > That's a fascinating approach but to a different problem than illustrated > in OP. > > Would you mind sharing (in private preferably to not distract from the > discussion) the > gist of the problem this solves? I'm really curious, as I've yet to > use intersect types :)! > > On Wed, 29 Mar 2023 at 11:47, Robert Landers <landers.rob...@gmail.com> > wrote: > > > > On Wed, Mar 29, 2023 at 10:31 AM Rokas Šleinius <rave...@gmail.com> > wrote: > > > > > > Enums were a very useful addition to PHP, however one aspect of them > is neither > > > explicitly documented - or seemingly even talked about. > > > > > > Enums were implemented as final so they cannot be extended nor can > extend > > > anything else. > > > > > > From a user perspective it's surprising - and actually limiting. > > > > > > USAGE EXAMPLE: > > > I am making an error management system: each error presented to the > user > > > must have a unique code visible. > > > > > > ```php > > > class SystemError > > > { > > > public function __construct( > > > private string $errorText, > > > private ErrorCode $code > > > ) { > > > } > > > > > > public function __toString(): > > > { > > > return $this->errorText . ' ' . $this->code->toString(); > > > } > > > } > > > // ... > > > > > > enum ErrorCode > > > { > > > case Code_1; > > > case Code_2; > > > > > > public function toString(): string > > > { > > > return 'Error code:' . substr($this->name, strlen('Code_')); > > > } > > > } > > > ``` > > > > > > Now I want to modify it to support different modules with different > > > namespaces for > > > errors, e.g. an ApiError, simple enough: > > > > > > ```php > > > enum BaseErrorCode > > > { > > > // ... > > > } > > > > > > enum ErrorCode extends BaseErrorCode > > > { > > > case Code_1; > > > case Code_2; > > > > > > // ... > > > } > > > > > > enum ApiErrorCode extends BaseErrorCode { > > > // ... > > > function toString(): string > > > { > > > return 'Error code:API-' . substr($this->name, > strlen('Code_')); > > > } > > > } > > > ``` > > > > > > This results in a syntax error. > > > > > > PROPOSAL: > > > > > > Enums should be able to extend other enums. > > > > > > For a complete wishlist, add: > > > * abstract enums; > > > * enums allowed to implement interfaces; > > > > > > However since I have no experience in PHP source code, I can only > > > provide the test suite for a possible PR this might have :( > > > > > > Do you think this is likely to get implemented? > > > > > > -- > > > PHP Internals - PHP Runtime Development Mailing List > > > To unsubscribe, visit: https://www.php.net/unsub.php > > > > > > > Hey Rokas, > > > > My approach has been to use an intersection type like: > > BackedEnum&MyCustomBehaviorInterface > > > > This works for me but it'd be interesting if something like that > > wouldn't work for you. > > -- > PHP Internals - PHP Runtime Development Mailing List > To unsubscribe, visit: https://www.php.net/unsub.php > >
