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?
>
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>
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.
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