ENUM

This is a PHP 7.4 to PHP 8.0 ENUM polyfill.

Quick start

Install the library using composer:

php composer.phar require tsitsulin/enum

Usage

Create a string enum:

<?php

declare(strict_types=1);

namespace Tsitsulin\Enum\Examples;

use Tsitsulin\Enum\PrivateEnum;
use Tsitsulin\Enum\StringEnum;

/**
 * @method static self Get()
 * @method static self Post()
 * @method static self Put()
 * @method static self Patch()
 * @method static self Delete()
 * 
 * phpcs:disable Generic.NamingConventions.UpperCaseConstantName
 */
final class HttpMethodEnum extends StringEnum
{
    use PrivateEnum;

    protected const Get = 'get';
    protected const Post = 'post';
    protected const Put = 'put';
    protected const Patch = 'patch';
    protected const Delete = 'delete';
}

Create an int enum:

<?php

declare(strict_types=1);

namespace Tsitsulin\Enum\Examples;

use Tsitsulin\Enum\PrivateEnum;
use Tsitsulin\Enum\IntEnum;

/**
 * @method static self Ok()
 * @method static self MovedPermanently()
 * 
 * phpcs:disable Generic.NamingConventions.UpperCaseConstantName
 */
final class HttpResponseEnum extends IntEnum
{
    use PrivateEnum;

    protected const Ok = 200;
    protected const MovedPermanently = 301;
}

PrivateEnum is optional enum instances isolation Trait:

• Each enum that has implemented it has isolated private instances.
• Otherwise, the instances of different enums will be collected in the StringEnum or/and IntEnum.
• It is recommended to implement it, so as not to break the encapsulation.

Access to name and value:

$caseName = HttpResponseEnum::Ok()->name; // 'Ok'
$caseValue = HttpResponseEnum::Ok()->value; // 200

Protected from modification or creation:

new HttpResponseEnum(); // Fatal error
HttpResponseEnum::Ok()->value = 100; // EnumCaseCannotBeModifiedError

UnitEnum cases:

foreach (HttpResponseEnum::cases() as $httpResponse) {
    print_r([$httpResponse->name => $httpResponse->value]);
};
// ['Ok' => 200]
// ['MovedPermanently' => 301]

BackedEnum from, tryFrom:

$caseName = HttpResponseEnum::from(200)->name); // name of case 'Ok'
$caseName = HttpResponseEnum::from('invalidValue')->name); // \Tsitsulin\Enum\Errors\UnexpectedEnumCaseTypeError
$caseName = HttpResponseEnum::tryFrom('invalidValue')->name); // Null

PHP 8.1 function enum_exists:

if (enum_exists(HttpResponseEnum::Ok())) { // True
    ...
}

Implementation differences from the original PHP 8.1 ENUM

• Access to ENUM:

  $original = HttpResponseEnum::Ok; // PHP 8.1
  $current = HttpResponseEnum::Ok();

• Typing:

  $original = function (enum|HttpResponseEnum $enum) {}
  $current = function(\Tsitsulin\Enum|HttpResponseEnum $enum) {}

• Originally name of the Enum itself is case-insensitive. Current Enum implementation based on classes and case-sensitive:
• Use deserialize_enum() this package function as synonym of unserialize() if deserialization is needed.
  • After deserialization via PHP unserialize():

  if ($enum1 === $deserializedEnum1) // False
  if ($enum1 == $deserializedEnum1) // True
  if ($enum1.name === $deserializedEnum1.name) // True
  if ($enum1.value === $deserializedEnum1.value) // True

  • After deserialization via deserialize_enum():

  $deserializedEnum1 = deserialize_enum($serializedEnum1);
  
  if ($enum1 === $deserializedEnum1) // True
  ...

  • Don't call Enum::Case()->unserialize() directly to make it easier to migrate to PHP 8.1+.