枚举值清单

无论是纯粹枚举还是回退枚举,都实现了一个叫 UnitEnum 的内部接口。 UnitEnum 包含了一个静态方法: cases()。 按照声明中的顺序,cases() 返回了打包的 array,包含全部定义的条目。

<?php

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

为 Enum 手动定义 cases() 方法会导致 fatal 错误。

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23
theking2 at king dot ma
3 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 $directive-> value . PHP_EOL;}?>Which results in:default-srcimg-srcfont-srcscript-srcstyle-src
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0
anhaia dot gabriel at gmail dot com
11 months ago
If you want to get all the values of the Enum in a list of `string`, you might do something like this:<?phpenum MyEnum: string{    case OPTION_A = 'option_a';    case OPTION_B = 'option_b';    case OPTION_C = 'option_c';    public static function values(): array    {        return array_map(fn ($case) => $case->value, self::cases());    }}?>
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