如何在PHP中实现类似Enum的功能？

php

2022-08-30 22:38:51

如何在PHP中使用类似枚举的功能（如Java和其他高级语言中提供的）？我知道PHP目前不允许你创建枚举，但是最接近的是什么？

答案 1

也许使用。const

class SomeClass {
    const FIRSTVAL = 1;
    const SECONDVAL = 2;
};

答案 2

这是@Kris代码的更新版本，以便更好地与较新版本的PHP配合使用。它是根据@lassombra评论作出的。

/**
 * Implements the abstract base for all enum types
 * @see http://stackoverflow.com/a/2324746/1003020
 * @see http://stackoverflow.com/a/254543/1003020
 *
 * Example of a typical enum:
 *
 *    class DayOfWeek extends Enum
 *    {
 *        const Sunday    = 0;
 *        const Monday    = 1;
 *        const Tuesday   = 2;
 *        const Wednesday = 3;
 *        const Thursday  = 4;
 *        const Friday    = 5;
 *        const Saturday  = 6;
 *    }
 *
 * Usage examples:
 *
 *     $monday = DayOfWeek::Monday                      // (int) 1
 *     DayOfWeek::isValidName('Monday')                 // (bool) true
 *     DayOfWeek::isValidName('monday', $strict = true) // (bool) false
 *     DayOfWeek::isValidValue(0)                       // (bool) true
 *     DayOfWeek::fromString('Monday')                  // (int) 1
 *     DayOfWeek::toString(DayOfWeek::Tuesday)          // (string) "Tuesday"
 *     DayOfWeek::toString(5)                           // (string) "Friday"
 **/
abstract class Enum
{
    private static $constCacheArray = NULL;

    private static function getConstants()
    {
        if (self::$constCacheArray == NULL) {
            self::$constCacheArray = [];
        }
        $calledClass = get_called_class();
        if (!array_key_exists($calledClass, self::$constCacheArray)) {
            $reflect = new \ReflectionClass($calledClass);
            self::$constCacheArray[$calledClass] = $reflect->getConstants();
        }
        return self::$constCacheArray[$calledClass];
    }

    public static function isValidName($name, $strict = false)
    {
        $constants = self::getConstants();

        if ($strict) {
            return array_key_exists($name, $constants);
        }

        $keys = array_map('strtolower', array_keys($constants));
        return in_array(strtolower($name), $keys);
    }

    public static function isValidValue($value, $strict = true)
    {
        $values = array_values(self::getConstants());
        return in_array($value, $values, $strict);
    }

    public static function fromString($name)
    {
        if (self::isValidName($name, $strict = true)) {
            $constants = self::getConstants();
            return $constants[$name];
        }

        return false;
    }

    public static function toString($value)
    {
        if (self::isValidValue($value, $strict = true)) {
            return array_search($value, self::getConstants());
        }

        return false;
    }
}