The BackedEnum interface

    (PHP 8 >= 8.1.0)

    Introduction

    The BackedEnum interface is automatically applied to backed enumerations by the engine. It may not be implemented by user-defined classes. Enumerations may not override its methods, as default implementations are provided by the engine. It is available only for type checks.

    Interface synopsis

    interface BackedEnum extends UnitEnum {
    /* Methods */
    public static from(int|string $value): static
    public static tryFrom(int|string $value): ?static
    /* Inherited methods */
    public static UnitEnum::cases(): array
    }

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    User Contributed Notes 1 note

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    whatuwant
    3 years ago
    As of PHP 8.1, while `UnitEnum` & `BackedEnum` cannot be implemented by user-defined classes, it seems they can be extended by user-defined interfaces and eventually be implemented by enums.<?phpinterface TestEnumInterface extends \BackedEnum{    public function foo(): string;}enum TestEnum: string implements TestEnumInterface{    case CASE_1 = 'case 1';    case CASE_2 = 'case 2';    public function foo(): string    {        return 'bar';    }}?>
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