Re: [IDEA] allow extending enum

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 <raveren@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.robert@gmail.com> > wrote: > > > > On Wed, Mar 29, 2023 at 10:31 AM Rokas Šleinius <raveren@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 > >