我使用接口而不是类:

interface DaysOfWeek
{
    const Sunday = 0;
    const Monday = 1;
    // etc.
}

var $today = DaysOfWeek::Sunday;

我试图用PHP创建一个枚举…这是非常有限的，因为它不支持对象作为枚举值，但仍然有点有用…

class ProtocolsEnum {

    const HTTP = '1';
    const HTTPS = '2';
    const FTP = '3';

    /**
     * Retrieve an enum value
     * @param string $name
     * @return string
     */
    public static function getValueByName($name) {
        return constant('self::'. $name);
    } 

    /**
     * Retrieve an enum key name
     * @param string $code
     * @return string
     */
    public static function getNameByValue($code) {
        foreach(get_class_constants() as $key => $val) {
            if($val == $code) {
                return $key;
            }
        }
    }

    /**
     * Retrieve associate array of all constants (used for creating droplist options)
     * @return multitype:
     */
    public static function toArray() {      
        return array_flip(self::get_class_constants());
    }

    private static function get_class_constants()
    {
        $reflect = new ReflectionClass(__CLASS__);
        return $reflect->getConstants();
    }
}

我知道这是一个旧线程，然而没有一个我所见过的解决方法真的看起来像枚举，因为几乎所有的解决方法都需要你手动分配值给枚举项，或者它需要你传递一个枚举键数组到一个函数。所以我创造了自己的解决方案。

要使用我的解决方案创建枚举类，可以简单地扩展下面的enum类，创建一堆静态变量(不需要初始化它们)，并在枚举类定义的下面调用yourEnumClass::init()。

edit: This only works in php >= 5.3, but it can probably be modified to work in older versions as well /** * A base class for enums. * * This class can be used as a base class for enums. * It can be used to create regular enums (incremental indices), but it can also be used to create binary flag values. * To create an enum class you can simply extend this class, and make a call to <yourEnumClass>::init() before you use the enum. * Preferably this call is made directly after the class declaration. * Example usages: * DaysOfTheWeek.class.php * abstract class DaysOfTheWeek extends Enum{ * static $MONDAY = 1; * static $TUESDAY; * static $WEDNESDAY; * static $THURSDAY; * static $FRIDAY; * static $SATURDAY; * static $SUNDAY; * } * DaysOfTheWeek::init(); * * example.php * require_once("DaysOfTheWeek.class.php"); * $today = date('N'); * if ($today == DaysOfTheWeek::$SUNDAY || $today == DaysOfTheWeek::$SATURDAY) * echo "It's weekend!"; * * Flags.class.php * abstract class Flags extends Enum{ * static $FLAG_1; * static $FLAG_2; * static $FLAG_3; * } * Flags::init(Enum::$BINARY_FLAG); * * example2.php * require_once("Flags.class.php"); * $flags = Flags::$FLAG_1 | Flags::$FLAG_2; * if ($flags & Flags::$FLAG_1) * echo "Flag_1 is set"; * * @author Tiddo Langerak */ abstract class Enum{ static $BINARY_FLAG = 1; /** * This function must be called to initialize the enumeration! * * @param bool $flags If the USE_BINARY flag is provided, the enum values will be binary flag values. Default: no flags set. */ public static function init($flags = 0){ //First, we want to get a list of all static properties of the enum class. We'll use the ReflectionClass for this. $enum = get_called_class(); $ref = new ReflectionClass($enum); $items = $ref->getStaticProperties(); //Now we can start assigning values to the items. if ($flags & self::$BINARY_FLAG){ //If we want binary flag values, our first value should be 1. $value = 1; //Now we can set the values for all items. foreach ($items as $key=>$item){ if (!isset($item)){ //If no value is set manually, we should set it. $enum::$$key = $value; //And we need to calculate the new value $value *= 2; } else { //If there was already a value set, we will continue starting from that value, but only if that was a valid binary flag value. //Otherwise, we will just skip this item. if ($key != 0 && ($key & ($key - 1) == 0)) $value = 2 * $item; } } } else { //If we want to use regular indices, we'll start with index 0. $value = 0; //Now we can set the values for all items. foreach ($items as $key=>$item){ if (!isset($item)){ //If no value is set manually, we should set it, and increment the value for the next item. $enum::$$key = $value; $value++; } else { //If a value was already set, we'll continue from that value. $value = $item+1; } } } } }

我已经在这里评论了一些其他的答案，所以我想我也会发表意见。 最后，由于PHP不支持类型化枚举，您可以选择以下两种方式之一:删除类型化枚举，或者接受它们极难有效删除的事实。

我更倾向于接受事实，而不是使用其他答案以某种方式使用的const方法:

abstract class Enum
{

    const NONE = null;

    final private function __construct()
    {
        throw new NotSupportedException(); // 
    }

    final private function __clone()
    {
        throw new NotSupportedException();
    }

    final public static function toArray()
    {
        return (new ReflectionClass(static::class))->getConstants();
    }

    final public static function isValid($value)
    {
        return in_array($value, static::toArray());
    }

}

枚举示例:

final class ResponseStatusCode extends Enum
{

    const OK                         = 200;
    const CREATED                    = 201;
    const ACCEPTED                   = 202;
    // ...
    const SERVICE_UNAVAILABLE        = 503;
    const GATEWAY_TIME_OUT           = 504;
    const HTTP_VERSION_NOT_SUPPORTED = 505;

}

使用Enum作为所有其他枚举扩展的基类，允许使用诸如toArray、isValid等辅助方法。对我来说，类型化的枚举(以及管理它们的实例)最终太混乱了。

假设

如果存在一个__getStatic魔法方法(最好还有一个__equals魔法方法)，那么大部分问题都可以通过一种多吨模式来缓解。

(以下是假设;它不会起作用，尽管也许有一天它会)

final class TestEnum
{

    private static $_values = [
        'FOO' => 1,
        'BAR' => 2,
        'QUX' => 3,
    ];
    private static $_instances = [];

    public static function __getStatic($name)
    {
        if (isset(static::$_values[$name]))
        {
            if (empty(static::$_instances[$name]))
            {
                static::$_instances[$name] = new static($name);
            }
            return static::$_instances[$name];
        }
        throw new Exception(sprintf('Invalid enumeration value, "%s"', $name));
    }

    private $_value;

    public function __construct($name)
    {
        $this->_value = static::$_values[$name];
    }

    public function __equals($object)
    {
        if ($object instanceof static)
        {
            return $object->_value === $this->_value;
        }
        return $object === $this->_value;
    }

}

$foo = TestEnum::$FOO; // object(TestEnum)#1 (1) {
                       //   ["_value":"TestEnum":private]=>
                       //   int(1)
                       // }

$zap = TestEnum::$ZAP; // Uncaught exception 'Exception' with message
                       // 'Invalid enumeration member, "ZAP"'

$qux = TestEnum::$QUX;
TestEnum::$QUX == $qux; // true
'hello world!' == $qux; // false

基于此要点，所有枚举的基类:

abstract class Enum {
    protected $val;

    protected function __construct($arg) {
        $this->val = $arg;
    }

    public function __toString() {
        return $this->val;
    }

    public function __set($arg1, $arg2) {
        throw new Exception("enum does not have property");
    }

    public function __get($arg1) {
        throw new Exception("enum does not have property");
    }

    // not really needed
    public function __call($arg1, $arg2) {
        throw new Exception("enum does not have method");
    }

    // not really needed
    static public function __callStatic($arg1, $arg2) {
        throw new Exception("enum does not have static method");
    }
}

你的枚举:

final class MyEnum extends Enum {
    static public function val1() {
        return new self("val1");
    }

    static public function val2() {
        return new self("val2");
    }

    static public function val3() {
        return new self("val3");
    }
}

测试:

$a = MyEnum::val1();
echo "1.the enum value is '$a'\n";

function consumeMyEnum(MyEnum $arg) {
    return "2.the return value is '$arg'\n";
}

echo consumeMyEnum($a);
$version = explode(".", PHP_VERSION);
if ($version[0] >= 7) {
    try {
        echo consumeMyEnum("val1");
    } catch (TypeError $e) {
        echo "3.passing argument error happens (PHP 7.0 and above)\n";
    }
}

echo ($a == MyEnum::val1()) ? "4.same\n" : "4.different\n";
echo ($a == MyEnum::val2()) ? "5.same\n" : "5.different\n";

$b = MyEnum::val1();
echo ($a == $b)  ? "6.same\n" : "6.different\n";
echo ($a === $b) ? "7.same\n" : "7.different\n";

$c = MyEnum::val2();
echo ($a == $c)  ? "8.same\n" : "8.different\n";
echo ($a === $c) ? "9.same\n" : "9.different\n";

switch ($c) {
    case MyEnum::val1(): echo "10.case of 1st\n"; break;
    case MyEnum::val2(): echo "11.case of 2nd\n"; break;
    case MyEnum::val3(): echo "12.case of 3rd\n"; break;
}

try {
    $a->prop = 10;
} catch (Exception $e) {
    echo "13.set property error happens\n";
}

try {
    echo $a->prop;
} catch (Exception $e) {
    echo "14.get property error happens\n";
}

try {
    echo $a->meth();
} catch (Exception $e) {
    echo "15.method call error happens\n";
}

try {
    echo MyEnum::meth();
} catch (Exception $e) {
    echo "16.static method call error happens\n";
}

class Ordinary {}
echo $a instanceof MyEnum   ? "17.MyEnum instance\n"   : "17.not MyEnum instance\n";
echo $a instanceof Enum     ? "18.Enum instance\n"     : "18.not Enum instance\n";
echo $a instanceof Ordinary ? "19.Ordinary instance\n" : "19.not Ordinary instance\n";

在网上试试:沙盒

我已经开始使用下面的方法，因为它使我能够对函数参数具有类型安全，在NetBeans中自动完成和良好的性能。我不太喜欢的一件事是你必须调用[扩展类名]::enumerate();在定义类之后。

abstract class Enum {

    private $_value;

    protected function __construct($value) {
        $this->_value = $value;
    }

    public function __toString() {
        return (string) $this->_value;
    }

    public static function enumerate() {
        $class = get_called_class();
        $ref = new ReflectionClass($class);
        $statics = $ref->getStaticProperties();
        foreach ($statics as $name => $value) {
            $ref->setStaticPropertyValue($name, new $class($value));
        }
    }
}

class DaysOfWeek extends Enum {
    public static $MONDAY = 0;
    public static $SUNDAY = 1;
    // etc.
}
DaysOfWeek::enumerate();

function isMonday(DaysOfWeek $d) {
    if ($d == DaysOfWeek::$MONDAY) {
        return true;
    } else {
        return false;
    }
}

$day = DaysOfWeek::$MONDAY;
echo (isMonday($day) ? "bummer it's monday" : "Yay! it's not monday");