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Date: Thu, 06 Nov 2025 09:26:21 -0600
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Subject: Re: [PHP-DEV] [RFC] [Discussion] BackedEnum::values() - Seeking feedback
 before formal RFC
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From: larry@garfieldtech.com ("Larry Garfield")

On Wed, Nov 5, 2025, at 10:09 PM, Mikhail Savin wrote:
> Hi internals,
>
> I would like to propose adding a native values() method to the BackedEnum
> interface that returns an array of all backing values. Before creating a
> formal RFC, I'm seeking feedback on the concept and approach.
>
> == Summary ==
>
> The proposal adds:
>
>     interface BackedEnum {
>         public static function values(): array;
>     }
>
> This would allow:
>
>     enum Status: string {
>         case Active = 'active';
>         case Inactive = 'inactive';
>     }
>   
>     Status::values(); // ['active', 'inactive']
>
> == Motivation ==
>
> This pattern is extremely common in the wild. Based on GitHub code search:
>
>   * ~3,860+ direct implementations of this exact pattern
>   * ~20,000-40,000 estimated real usage when accounting for shared traits
>   * Used in major frameworks: Symfony core (TypeIdentifier.php),
>     Laravel ecosystem
>   * Documented by PHP.net: The manual itself shows EnumValuesTrait as
>     an example

Correction: The manual does not show an EnumValuesTrait that I can find.  There is a *comment* in the manual that includes this method, but that's not part of the manual proper, and frankly 90% of comments in the manual should be removed.  (cf: https://www.php.net/manual/en/language.enumerations.traits.php#129250)

> Common use cases:
>   * Database migrations: $table->enum('status', Status::values())
>   * Form validation: $validator->rule('status', 'in', Status::values())
>   * API responses: ['allowed_statuses' => Status::values()]
>
> == Implementation ==
>
> I have a working implementation with tests:
> https://github.com/php/php-src/pull/20398
>
> The implementation:
>   * Mirrors the existing cases() method structure
>   * Extracts the value property from each case
>   * Returns an indexed array (0, 1, 2, ...)
>   * Only available on BackedEnum, not UnitEnum
>   * All tests pass

I am unclear why this is a major advantage over array_column(Status::cases(), 'value');

> == Backward Compatibility - Important Discussion Point ==
>
> This is a breaking change. Enums that already define a values() method
> will fail with:
>
>     Fatal error: Cannot redeclare BackedEnum::values()
>
> Based on ecosystem research:
>   * ~24,000-44,000 enum instances will break
>   * All implementations are functionally identical to what's being proposed
>   * Migration is mechanical: just delete the user-defined method

This is a hard-stop.  There are hundreds of thousands of packages in the wild that need to support multiple PHP versions.  Nearly all packaglist packages (which I presume is where you're drawing the research from; either that or GitHub which will give a similar result set) support at least two consecutive versions, if not 4, 5, or 6.

A hard break like this would essentially mean the packages containing those 40,000 enums would be unable to support both PHP 8.5 and 8.6 at the same time.  That's simply not an acceptable impact on the ecosystem, regardless of how nice the feature may or may not be.

--Larry Garfield