PHP: Value listing

Value listing

Both Pure Enums and Backed Enums implement an internal interface named UnitEnum. UnitEnum includes a static method cases(). cases() returns a packed array of all defined Cases in the order of declaration.

<?php

Suit::cases();
// Produces: [Suit::Hearts, Suit::Diamonds, Suit::Clubs, Suit::Spades]
?>

Manually defining a cases() method on an Enum will result in a fatal error.

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User Contributed Notes 2 notes

down

theking2 at king dot ma ¶

2 years ago

As ::cases() creates a Iteratable it is possible to use it in a foreach loop. In combination with value backed enum this can result in very compact and very readable code:

<?php
/** Content Security Policy directives */
enum CspDirective: String {
  case Default = "default-src";
  case Image = "img-src";
  case Font = "font-src";
  case Script = "script-src";
  case Style = "style-src";
}

/** list all CSP directives */
foreach( CspSource::cases() as $directive ) {
  echo $directive-> value . PHP_EOL;
}
?>
Which results in:
default-src
img-src
font-src
script-src
style-src

down

anhaia dot gabriel at gmail dot com ¶

3 months ago

If you want to get all the values of the Enum in a list of `string`, you might do something like this:

<?php

enum MyEnum: string
{
    case OPTION_A = 'option_a';
    case OPTION_B = 'option_b';
    case OPTION_C = 'option_c';

    public static function values(): array
    {
        return array_map(fn ($case) => $case->value, self::cases());
    }
}

?>

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