How Do I Use Enumerations in PHP, Including Workarounds for Versions Before 8.1?

Enumerations in PHP: PHP 8.1 Support and Workarounds

PHP has long lacked native enumerations, leaving developers seeking workarounds. However, with the release of PHP 8.1, full-fledged enum support has finally arrived.

PHP 8.1: Native Enums

Starting with PHP 8.1, enums are officially supported. They provide a concise and type-safe way to define sets of predefined values:

enum DaysOfWeek: int
{
    case Sunday = 0;
    case Monday = 1;
    // etc.
}

Workarounds for PHP 8.0 and Earlier

Prior to PHP 8.1, several workarounds were commonly used:

• Constants: Constants provide global, immutable values. However, they can lead to namespace collisions and are not as versatile as true enums.
• Arrays: Arrays are more flexible but can be overridden and lack autofill support in IDEs.

A more advanced workaround involves creating a base enum class with static validation methods:

abstract class BasicEnum
{
    // ...
    public static function isValidName($name, $strict = false) {}
    public static function isValidValue($value, $strict = true) {}
}

Extending this class allows for straightforward input validation:

abstract class DaysOfWeek extends BasicEnum
{
    // ...
}

DaysOfWeek::isValidName('Humpday');                  // false
DaysOfWeek::isValidValue(7);                         // false

SplEnum for PHP 5.3

If using PHP 5.3 or later, SplEnum provides a more robust workaround:

$days = new SplEnum(array(
    'Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday'
));

if ($days->isValid('Monday')) {
    // ...
}

Conclusion

Native enumerations in PHP 8.1 simplify code and improve type safety. For earlier versions, various workarounds exist, including constants, arrays, and the BasicEnum or SplEnum classes.

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