PHP和枚举


1149

我知道PHP没有本地枚举。但是我已经习惯了Java世界中的他们。我很乐意使用枚举来提供IDE的自动完成功能可以理解的预定义值。

常量可以解决问题,但是存在名称空间冲突问题,并且(或者实际上是因为)它们是全局的。数组没有名称空间问题,但是它们太模糊了,它们可以在运行时被覆盖,而IDE很少(从来没有?)不知道如何自动填充键。

您通常使用任何解决方案/解决方法吗?有谁回想起PHP家伙是否对枚举有任何想法或决定?



1
我创建了一个变通函数,该函数枚举常量是否为按位枚举。:没注意到你问过,但我有比类变量更好的解决方案在这里stackoverflow.com/questions/3836385/...
NoodleOfDeath


您介意多分享一些有关Constants问题的信息吗?“常量可以解决问题,但是存在名称空间冲突问题,并且(实际上是因为)它们是全局的。”
许鼎

Answers:


1492

根据使用情况,我通常会使用类似以下的简单内容:

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

$today = DaysOfWeek::Sunday;

但是,其他用例可能需要更多的常量和值验证。根据以下有关反射的评论以及其他一些注意事项,这是一个扩展的示例,可能会更好地服务于更广泛的案例:

abstract class BasicEnum {
    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);
    }
}

通过创建扩展BasicEnum的简单枚举类,您现在可以将方法用于简单的输入验证:

abstract class DaysOfWeek extends BasicEnum {
    const Sunday = 0;
    const Monday = 1;
    const Tuesday = 2;
    const Wednesday = 3;
    const Thursday = 4;
    const Friday = 5;
    const Saturday = 6;
}

DaysOfWeek::isValidName('Humpday');                  // false
DaysOfWeek::isValidName('Monday');                   // true
DaysOfWeek::isValidName('monday');                   // true
DaysOfWeek::isValidName('monday', $strict = true);   // false
DaysOfWeek::isValidName(0);                          // false

DaysOfWeek::isValidValue(0);                         // true
DaysOfWeek::isValidValue(5);                         // true
DaysOfWeek::isValidValue(7);                         // false
DaysOfWeek::isValidValue('Friday');                  // false

附带说明一下,每当我在不会更改数据的静态/ const类上至少使用一次反射(例如在枚举中)时,都会缓存这些反射调用的结果,因为每次都使用新的反射对象最终将对性能产生显着影响(存储在多个枚举的关联数组中)。

现在大多数人终于升级到了至少5.3,并且SplEnum可以使用,这当然也是一个可行的选择-只要您不介意在代码库中具有实际枚举实例的传统不直观的概念。在上面的示例中,BasicEnumand DaysOfWeek根本不能实例化,也不应该实例化。


70
我也用这个 您可能还会考虑创建类abstractfinal,因此无法实例化或扩展它。
ryeguy 2011年

21
你可以做一个类都abstractfinal?我知道在Java中这是不允许的。你可以用PHP做到这一点?
corsiKa 2011年

20
@ryeguy看来你不能让这两个 abstractfinal。在那种情况下,我会去摘要。
妮可(Nicole)

45
关于摘要或最终形式;我将它们
定型

21
使用0时要格外小心,这样您就不会遇到任何无法预料的虚假比较问题,例如,nullswitch声明中与和朋友等价。到过那里。
yitznewton

185

也有一个本机扩展。该SplEnum

SplEnum提供了在PHP中本地模拟和创建枚举对象的功能。

http://www.php.net/manual/zh/class.splenum.php

注意:

https://www.php.net/manual/zh/spl-types.installation.php

PECL扩展未与PHP捆绑在一起。

该PECL扩展的DLL当前不可用。


4
这是一个带有脾脏的示例:dreamincode.net/forums/topic/201638-enum-in-php
Nordes 2011年

4
我回滚,看到链接后,我更喜欢它。它给了我上下文信息。
markus

5
我又回滚了。我不希望你们编辑链接。
markus

6
使用时要小心。SPL类型是试验性的:“此扩展名是实验性的。此扩展名的行为,包括其功能名称和与该扩展名有关的任何其他文档,在将来的PHP版本中可能会更改,恕不另行通知。使用此扩展名后果自负。 ”
bzeaman

6
SplEnum未与PHP捆绑在一起,它需要扩展
SPL_Types

46

那类常量呢?

<?php

class YourClass
{
    const SOME_CONSTANT = 1;

    public function echoConstant()
    {
        echo self::SOME_CONSTANT;
    }
}

echo YourClass::SOME_CONSTANT;

$c = new YourClass;
$c->echoConstant();

我喜欢这种简单的方法
David Lemon

echoConstant可以替换为__toString。然后就是echo $c
Justinas

35

上面的最高答案是太棒了。但是,如果您extend以两种不同的方式进行操作,则无论哪种扩展首先完成,都会导致对函数的调用将创建缓存。然后,此高速缓存将被所有后续调用使用,无论这些调用是由...发起的任何扩展名。

要解决此问题,请将变量和第一个函数替换为:

private static $constCacheArray = null;

private static function getConstants() {
    if (self::$constCacheArray === null) self::$constCacheArray = array();

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

    return self::$constCacheArray[$calledClass];
}

2
有这个问题。Brian或具有编辑权限的人应在接受的答案中对其进行触摸。我使用getConstants()函数中的'static ::'方法而不是'self ::'在代码中解决了此问题,并在子枚举中重新声明了$ constCache。
Sp3igel 2014年

它可能不是很性感,但是使用接口常量可能是使用PHP的最佳方法。
安东尼·鲁特里奇

27

我使用了带有常量的类:

class Enum {
    const NAME       = 'aaaa';
    const SOME_VALUE = 'bbbb';
}

print Enum::NAME;

27

我用interface代替class

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

var $today = DaysOfWeek::Sunday;

6
class Foo implements DaysOfWeek { }然后Foo::Sunday...什么?
Dan Lugg

3
问题的作者要求为以下两个问题提供解决方案:名称空间和IDE自动完成。正如评价最高的答案所建议的那样,最简单的方法是使用class(或interface,这只是一个偏好问题)。
Andi T

4
接口用于强制实现类实现的完整性,这不在接口的范围之内
user3886650

2
@ user3886650接口可以并且曾经在Java中用于保持常量值。因此,您不必为了获得常量值而实例化一个类,任何IDE都可以在其上完成代码。同样,如果您创建一个实现该接口的类,它将继承所有这些常量-有时非常方便。
亚历克斯

@ user3886650是的,但是在PHP中,接口可以具有常量。此外,实现类或其子类不能覆盖这些接口常量。实际上,就PHP而言,这是最好的答案,因为可以被覆盖的任何东西实际上并没有像常量那样正常工作。常量应该表示常量,而不是有时(即使多态性有时会有用)也不是。
安东尼·鲁特里奇

25

我在这里评论了其他一些答案,因此我认为自己也可以考虑。归根结底,由于PHP不支持类型枚举,因此您可以采用以下两种方法之一:破解类型枚举,或者忍受很难有效破解的事实。

我更喜欢事实,而不是使用const此处其他答案以某种方式使用的方法:

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作为基类,所有其他枚举延伸允许辅助方法,诸如toArrayisValid等。对我来说,键入枚举(以及管理它们的实例)最终太混乱了。


假想

如果存在,则存在__getStatic魔术方法(最好也有__equals魔术方法),其中的许多方法可以通过某种多态模式来缓解。

以下是假设的;虽然可能有一天会起作用,但它不会起作用

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

我真的很喜欢这个答案的简单性。您可以稍后再回过头来快速了解它的工作原理,而又不会像您采用某种骇人听闻的方法那样。可惜它没有更多的赞成票。
Reactgular

23

好吧,对于像PHP中的枚举之类的简单java,我使用:

class SomeTypeName {
    private static $enum = array(1 => "Read", 2 => "Write");

    public function toOrdinal($name) {
        return array_search($name, self::$enum);
    }

    public function toString($ordinal) {
        return self::$enum[$ordinal];
    }
}

并称之为:

SomeTypeName::toOrdinal("Read");
SomeTypeName::toString(1);

但是我是PHP的新手,在语法上苦苦挣扎,所以这可能不是最好的方法。我用“类常量”进行了一些实验,使用“反射”从其值中获取常量名称,可能会更整洁。


好的答案,其他大多数答案都在使用类。但是您不能有嵌套的类。
Keyo

这样的好处是可以使用foreach遍历值。不利于未捕捉到非法价值。
Bob Stein

2
IDE中没有自动完成功能,因此会刺激猜测工作。常量将启用自动完成功能,听起来更好。
KrekkieD 2014年

19

四年后,我再次遇到了这个问题。我当前的方法是这样的,因为它允许在IDE中完成代码以及实现类型安全性:

基类:

abstract class TypedEnum
{
    private static $_instancedValues;

    private $_value;
    private $_name;

    private function __construct($value, $name)
    {
        $this->_value = $value;
        $this->_name = $name;
    }

    private static function _fromGetter($getter, $value)
    {
        $reflectionClass = new ReflectionClass(get_called_class());
        $methods = $reflectionClass->getMethods(ReflectionMethod::IS_STATIC | ReflectionMethod::IS_PUBLIC);    
        $className = get_called_class();

        foreach($methods as $method)
        {
            if ($method->class === $className)
            {
                $enumItem = $method->invoke(null);

                if ($enumItem instanceof $className && $enumItem->$getter() === $value)
                {
                    return $enumItem;
                }
            }
        }

        throw new OutOfRangeException();
    }

    protected static function _create($value)
    {
        if (self::$_instancedValues === null)
        {
            self::$_instancedValues = array();
        }

        $className = get_called_class();

        if (!isset(self::$_instancedValues[$className]))
        {
            self::$_instancedValues[$className] = array();
        }

        if (!isset(self::$_instancedValues[$className][$value]))
        {
            $debugTrace = debug_backtrace();
            $lastCaller = array_shift($debugTrace);

            while ($lastCaller['class'] !== $className && count($debugTrace) > 0)
            {
                $lastCaller = array_shift($debugTrace);
            }

            self::$_instancedValues[$className][$value] = new static($value, $lastCaller['function']);
        }

        return self::$_instancedValues[$className][$value];
    }

    public static function fromValue($value)
    {
        return self::_fromGetter('getValue', $value);
    }

    public static function fromName($value)
    {
        return self::_fromGetter('getName', $value);
    }

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

    public function getName()
    {
        return $this->_name;
    }
}

示例枚举:

final class DaysOfWeek extends TypedEnum
{
    public static function Sunday() { return self::_create(0); }    
    public static function Monday() { return self::_create(1); }
    public static function Tuesday() { return self::_create(2); }   
    public static function Wednesday() { return self::_create(3); }
    public static function Thursday() { return self::_create(4); }  
    public static function Friday() { return self::_create(5); }
    public static function Saturday() { return self::_create(6); }      
}

用法示例:

function saveEvent(DaysOfWeek $weekDay, $comment)
{
    // store week day numeric value and comment:
    $myDatabase->save('myeventtable', 
       array('weekday_id' => $weekDay->getValue()),
       array('comment' => $comment));
}

// call the function, note: DaysOfWeek::Monday() returns an object of type DaysOfWeek
saveEvent(DaysOfWeek::Monday(), 'some comment');

请注意,同一枚举条目的所有实例都相同:

$monday1 = DaysOfWeek::Monday();
$monday2 = DaysOfWeek::Monday();
$monday1 === $monday2; // true

您也可以在switch语句中使用它:

function getGermanWeekDayName(DaysOfWeek $weekDay)
{
    switch ($weekDay)
    {
        case DaysOfWeek::Monday(): return 'Montag';
        case DaysOfWeek::Tuesday(): return 'Dienstag';
        // ...
}

您还可以按名称或值创建一个枚举条目:

$monday = DaysOfWeek::fromValue(2);
$tuesday = DaysOfWeek::fromName('Tuesday');

或者,您也可以从现有的枚举条目中获取名称(即函数名称):

$wednesday = DaysOfWeek::Wednesday()
echo $wednesDay->getName(); // Wednesday

+1为私有构造函数。我不会做辅助抽象类,而只是一个简单的类,私有构造函数以及一些const Monday = DaysOfWeek('Monday');
Kangur,

9

我在github上找到了这个库,我认为它提供了一个非常不错的替代方法。

受SplEnum启发的PHP Enum实现

  • 您可以输入提示: function setAction(Action $action) {
  • 您可以使用方法来丰富枚举(例如formatparse,...)
  • 您可以扩展枚举以添加新值(使您的枚举final阻止它)
  • 您可以获得所有可能值的列表(请参见下文)

宣言

<?php
use MyCLabs\Enum\Enum;

/**
 * Action enum
 */
class Action extends Enum
{
    const VIEW = 'view';
    const EDIT = 'edit';
}

用法

<?php
$action = new Action(Action::VIEW);

// or
$action = Action::VIEW();

类型提示枚举值:

<?php
function setAction(Action $action) {
    // ...
}

1
这是正确的答案(目前为止,直到enumPHP 7.x中已添加),因为它允许类型提示。
托比亚

1
这不仅允许类型提示,而且由于__toString()它的魔力,它使您可以执行枚举通常想要的操作-在switchor if语句中使用它们,直接与const的值进行比较。缺少本机枚举支持的最佳方法IMO。
LinusR

7

如果您需要使用全局唯一的枚举(即,即使在比较不同枚举之间的元素时),也易于使用,请随时使用以下代码。我还添加了一些我认为有用的方法。您可以在代码顶部的注释中找到示例。

<?php

/**
 * Class Enum
 * 
 * @author Christopher Fox <christopher.fox@gmx.de>
 *
 * @version 1.0
 *
 * This class provides the function of an enumeration.
 * The values of Enum elements are unique (even between different Enums)
 * as you would expect them to be.
 *
 * Constructing a new Enum:
 * ========================
 *
 * In the following example we construct an enum called "UserState"
 * with the elements "inactive", "active", "banned" and "deleted".
 * 
 * <code>
 * Enum::Create('UserState', 'inactive', 'active', 'banned', 'deleted');
 * </code>
 *
 * Using Enums:
 * ============
 *
 * The following example demonstrates how to compare two Enum elements
 *
 * <code>
 * var_dump(UserState::inactive == UserState::banned); // result: false
 * var_dump(UserState::active == UserState::active); // result: true
 * </code>
 *
 * Special Enum methods:
 * =====================
 *
 * Get the number of elements in an Enum:
 *
 * <code>
 * echo UserState::CountEntries(); // result: 4
 * </code>
 *
 * Get a list with all elements of the Enum:
 *
 * <code>
 * $allUserStates = UserState::GetEntries();
 * </code>
 *
 * Get a name of an element:
 *
 * <code>
 * echo UserState::GetName(UserState::deleted); // result: deleted
 * </code>
 *
 * Get an integer ID for an element (e.g. to store as a value in a database table):
 * This is simply the index of the element (beginning with 1).
 * Note that this ID is only unique for this Enum but now between different Enums.
 *
 * <code>
 * echo UserState::GetDatabaseID(UserState::active); // result: 2
 * </code>
 */
class Enum
{

    /**
     * @var Enum $instance The only instance of Enum (Singleton)
     */
    private static $instance;

    /**
     * @var array $enums    An array of all enums with Enum names as keys
     *          and arrays of element names as values
     */
    private $enums;

    /**
     * Constructs (the only) Enum instance
     */
    private function __construct()
    {
        $this->enums = array();
    }

    /**
     * Constructs a new enum
     *
     * @param string $name The class name for the enum
     * @param mixed $_ A list of strings to use as names for enum entries
     */
    public static function Create($name, $_)
    {
        // Create (the only) Enum instance if this hasn't happened yet
        if (self::$instance===null)
        {
            self::$instance = new Enum();
        }

        // Fetch the arguments of the function
        $args = func_get_args();
        // Exclude the "name" argument from the array of function arguments,
        // so only the enum element names remain in the array
        array_shift($args);
        self::$instance->add($name, $args);
    }

    /**
     * Creates an enumeration if this hasn't happened yet
     * 
     * @param string $name The class name for the enum
     * @param array $fields The names of the enum elements
     */
    private function add($name, $fields)
    {
        if (!array_key_exists($name, $this->enums))
        {
            $this->enums[$name] = array();

            // Generate the code of the class for this enumeration
            $classDeclaration =     "class " . $name . " {\n"
                        . "private static \$name = '" . $name . "';\n"
                        . $this->getClassConstants($name, $fields)
                        . $this->getFunctionGetEntries($name)
                        . $this->getFunctionCountEntries($name)
                        . $this->getFunctionGetDatabaseID()
                        . $this->getFunctionGetName()
                        . "}";

            // Create the class for this enumeration
            eval($classDeclaration);
        }
    }

    /**
     * Returns the code of the class constants
     * for an enumeration. These are the representations
     * of the elements.
     * 
     * @param string $name The class name for the enum
     * @param array $fields The names of the enum elements
     *
     * @return string The code of the class constants
     */
    private function getClassConstants($name, $fields)
    {
        $constants = '';

        foreach ($fields as $field)
        {
            // Create a unique ID for the Enum element
            // This ID is unique because class and variables
            // names can't contain a semicolon. Therefore we
            // can use the semicolon as a separator here.
            $uniqueID = $name . ";" . $field;
            $constants .=   "const " . $field . " = '". $uniqueID . "';\n";
            // Store the unique ID
            array_push($this->enums[$name], $uniqueID);
        }

        return $constants;
    }

    /**
     * Returns the code of the function "GetEntries()"
     * for an enumeration
     * 
     * @param string $name The class name for the enum
     *
     * @return string The code of the function "GetEntries()"
     */
    private function getFunctionGetEntries($name) 
    {
        $entryList = '';        

        // Put the unique element IDs in single quotes and
        // separate them with commas
        foreach ($this->enums[$name] as $key => $entry)
        {
            if ($key > 0) $entryList .= ',';
            $entryList .= "'" . $entry . "'";
        }

        return  "public static function GetEntries() { \n"
            . " return array(" . $entryList . ");\n"
            . "}\n";
    }

    /**
     * Returns the code of the function "CountEntries()"
     * for an enumeration
     * 
     * @param string $name The class name for the enum
     *
     * @return string The code of the function "CountEntries()"
     */
    private function getFunctionCountEntries($name) 
    {
        // This function will simply return a constant number (e.g. return 5;)
        return  "public static function CountEntries() { \n"
            . " return " . count($this->enums[$name]) . ";\n"
            . "}\n";
    }

    /**
     * Returns the code of the function "GetDatabaseID()"
     * for an enumeration
     * 
     * @return string The code of the function "GetDatabaseID()"
     */
    private function getFunctionGetDatabaseID()
    {
        // Check for the index of this element inside of the array
        // of elements and add +1
        return  "public static function GetDatabaseID(\$entry) { \n"
            . "\$key = array_search(\$entry, self::GetEntries());\n"
            . " return \$key + 1;\n"
            . "}\n";
    }

    /**
     * Returns the code of the function "GetName()"
     * for an enumeration
     *
     * @return string The code of the function "GetName()"
     */
    private function getFunctionGetName()
    {
        // Remove the class name from the unique ID 
        // and return this value (which is the element name)
        return  "public static function GetName(\$entry) { \n"
            . "return substr(\$entry, strlen(self::\$name) + 1 , strlen(\$entry));\n"
            . "}\n";
    }

}


?>

1
我很喜欢这个 但是,主要的抱怨之一是IDE能够获取自动完成的值。我不确定如果没有针对IDE的自定义插件,是否能够做到这一点。不是说它不能完成,而是需要一些工作。
corsiKa 2011年

2
使用eval()只是为了声明新的Enums运行时?真是的 我没有感觉 在定义正确的类之前,如何防止其他类创建不正确的Enum类?在运行时之前不是枚举吗?就像@corsiKa所暗示的那样,没有IDE自动完成功能。我看到的唯一好处是延迟编码。
2014年

7

我也喜欢Java的枚举,因此我以这种方式编写我的枚举,我认为这是Java枚举中最相似的行为,当然,如果有人想使用Java的更多方法,请在此处或抽象类,但核心思想嵌入在下面的代码中


class FruitsEnum {

    static $APPLE = null;
    static $ORANGE = null;

    private $value = null;

    public static $map;

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

    public static function init () {
        self::$APPLE  = new FruitsEnum("Apple");
        self::$ORANGE = new FruitsEnum("Orange");
        //static map to get object by name - example Enum::get("INIT") - returns Enum::$INIT object;
        self::$map = array (
            "Apple" => self::$APPLE,
            "Orange" => self::$ORANGE
        );
    }

    public static function get($element) {
        if($element == null)
            return null;
        return self::$map[$element];
    }

    public function getValue() {
        return $this->value;
    }

    public function equals(FruitsEnum $element) {
        return $element->getValue() == $this->getValue();
    }

    public function __toString () {
        return $this->value;
    }
}
FruitsEnum::init();

var_dump(FruitsEnum::$APPLE->equals(FruitsEnum::$APPLE)); //true
var_dump(FruitsEnum::$APPLE->equals(FruitsEnum::$ORANGE)); //false
var_dump(FruitsEnum::$APPLE instanceof FruitsEnum); //true
var_dump(FruitsEnum::get("Apple")->equals(FruitsEnum::$APPLE)); //true - enum from string
var_dump(FruitsEnum::get("Apple")->equals(FruitsEnum::get("Orange"))); //false

3
我正在做几乎相同的事情,尽管有两个小的补充:我已经将静态值隐藏在静态获取器后面。原因之一是,我在视觉上FruitsEnum::Apple()优于FruitsEnum::$Apple,但更重要的原因是防止其他人设置$APPLE,从而破坏了整个应用程序的枚举。另一个是简单的私有静态标志$initialized,可确保init()在首次调用后调用变为无操作(因此,任何人都不会对此感到混乱)。
Martin Ender 2013年

我确实喜欢马丁。.init()很奇怪,我也不介意使用吸气剂方法。
塞巴斯2015年

7
abstract class Enumeration
{
    public static function enum() 
    {
        $reflect = new ReflectionClass( get_called_class() );
        return $reflect->getConstants();
    }
}


class Test extends Enumeration
{
    const A = 'a';
    const B = 'b';    
}


foreach (Test::enum() as $key => $value) {
    echo "$key -> $value<br>";
}


5

我在PHP中看到的枚举最常见的解决方案是创建一个通用的枚举类,然后对其进行扩展。你可能会先看看这个

更新:或者,我从phpclasses.org 找到了这个


1
尽管实现起来很巧妙,并且可能会完成任务,但缺点是IDE可能不知道如何自动填充枚举。我无法从phpclasses.org检查它,因为它要我注册。
亨里克·保罗

5

这是一个用于处理php中类型安全枚举的github库:

该库处理类的生成,类的缓存,并实现了类型安全枚举设计模式,并提供了几种用于处理枚举的辅助方法,例如为枚举排序检索序数或为枚举组合检索二进制值。

生成的代码使用一个普通的旧php模板文件,该文件也是可配置的,因此您可以提供自己的模板。

这是用phpunit覆盖的完整测试。

github上的php-enums(随意分叉)

用法:(有关详细信息,请参见@ use.php或单元测试)

<?php
//require the library
require_once __DIR__ . '/src/Enum.func.php';

//if you don't have a cache directory, create one
@mkdir(__DIR__ . '/cache');
EnumGenerator::setDefaultCachedClassesDir(__DIR__ . '/cache');

//Class definition is evaluated on the fly:
Enum('FruitsEnum', array('apple' , 'orange' , 'rasberry' , 'bannana'));

//Class definition is cached in the cache directory for later usage:
Enum('CachedFruitsEnum', array('apple' , 'orange' , 'rasberry' , 'bannana'), '\my\company\name\space', true);

echo 'FruitsEnum::APPLE() == FruitsEnum::APPLE(): ';
var_dump(FruitsEnum::APPLE() == FruitsEnum::APPLE()) . "\n";

echo 'FruitsEnum::APPLE() == FruitsEnum::ORANGE(): ';
var_dump(FruitsEnum::APPLE() == FruitsEnum::ORANGE()) . "\n";

echo 'FruitsEnum::APPLE() instanceof Enum: ';
var_dump(FruitsEnum::APPLE() instanceof Enum) . "\n";

echo 'FruitsEnum::APPLE() instanceof FruitsEnum: ';
var_dump(FruitsEnum::APPLE() instanceof FruitsEnum) . "\n";

echo "->getName()\n";
foreach (FruitsEnum::iterator() as $enum)
{
  echo "  " . $enum->getName() . "\n";
}

echo "->getValue()\n";
foreach (FruitsEnum::iterator() as $enum)
{
  echo "  " . $enum->getValue() . "\n";
}

echo "->getOrdinal()\n";
foreach (CachedFruitsEnum::iterator() as $enum)
{
  echo "  " . $enum->getOrdinal() . "\n";
}

echo "->getBinary()\n";
foreach (CachedFruitsEnum::iterator() as $enum)
{
  echo "  " . $enum->getBinary() . "\n";
}

输出:

FruitsEnum::APPLE() == FruitsEnum::APPLE(): bool(true)
FruitsEnum::APPLE() == FruitsEnum::ORANGE(): bool(false)
FruitsEnum::APPLE() instanceof Enum: bool(true)
FruitsEnum::APPLE() instanceof FruitsEnum: bool(true)
->getName()
  APPLE
  ORANGE
  RASBERRY
  BANNANA
->getValue()
  apple
  orange
  rasberry
  bannana
->getValue() when values have been specified
  pig
  dog
  cat
  bird
->getOrdinal()
  1
  2
  3
  4
->getBinary()
  1
  2
  4
  8

4

我已经开始使用以下方法,因为它使我能够对函数参数进行类型安全,在NetBeans中自动完成并具有良好的性能。我不太喜欢的一件事是,您必须[extended class name]::enumerate();在定义类后调用。

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");

没有什么可以阻止您重新定义枚举值:DaysOfWeek::$MONDAY = 3;
KrekkieD 2014年

@BrianFisher,我知道这很晚了,但是,如果您不喜欢[extended class name]::enumerate();在定义后调用,为什么不在构造中执行呢?
Can

4

我下面的Enum类定义是强类型的,并且使用和定义都非常自然

定义:

class Fruit extends Enum {
    static public $APPLE = 1;
    static public $ORANGE = 2;
}
Fruit::initialize(); //Can also be called in autoloader

切换枚举

$myFruit = Fruit::$APPLE;

switch ($myFruit) {
    case Fruit::$APPLE  : echo "I like apples\n";  break;
    case Fruit::$ORANGE : echo "I hate oranges\n"; break;
}

>> I like apples

将枚举作为参数传递(严格键入)

/** Function only accepts Fruit enums as input**/
function echoFruit(Fruit $fruit) {
    echo $fruit->getName().": ".$fruit->getValue()."\n";
}

/** Call function with each Enum value that Fruit has */
foreach (Fruit::getList() as $fruit) {
    echoFruit($fruit);
}

//Call function with Apple enum
echoFruit(Fruit::$APPLE)

//Will produce an error. This solution is strongly typed
echoFruit(2);

>> APPLE: 1
>> ORANGE: 2
>> APPLE: 1
>> Argument 1 passed to echoFruit() must be an instance of Fruit, integer given

以字符串形式返回Enum

echo "I have an $myFruit\n";

>> I have an APPLE

通过整数获取枚举

$myFruit = Fruit::getByValue(2);

echo "Now I have an $myFruit\n";

>> Now I have an ORANGE

按名称获取枚举

$myFruit = Fruit::getByName("APPLE");

echo "But I definitely prefer an $myFruit\n\n";

>> But I definitely prefer an APPLE

枚举类:

/**
 * @author Torge Kummerow
 */
class Enum {

    /**
     * Holds the values for each type of Enum
     */
    static private $list = array();

    /**
     * Initializes the enum values by replacing the number with an instance of itself
     * using reflection
     */
    static public function initialize() {
        $className = get_called_class();
        $class = new ReflectionClass($className);
        $staticProperties = $class->getStaticProperties();

        self::$list[$className] = array();

        foreach ($staticProperties as $propertyName => &$value) {
            if ($propertyName == 'list')
                continue;

            $enum = new $className($propertyName, $value);
            $class->setStaticPropertyValue($propertyName, $enum);
            self::$list[$className][$propertyName] = $enum;
        } unset($value);
    }


    /**
     * Gets the enum for the given value
     *
     * @param integer $value
     * @throws Exception
     *
     * @return Enum
     */
    static public function getByValue($value) {
        $className = get_called_class();
        foreach (self::$list[$className] as $propertyName=>&$enum) {
            /* @var $enum Enum */
            if ($enum->value == $value)
                return $enum;
        } unset($enum);

        throw new Exception("No such enum with value=$value of type ".get_called_class());
    }

    /**
     * Gets the enum for the given name
     *
     * @param string $name
     * @throws Exception
     *
     * @return Enum
     */
    static public function getByName($name) {
        $className = get_called_class();
        if (array_key_exists($name, static::$list[$className]))
            return self::$list[$className][$name];

        throw new Exception("No such enum ".get_called_class()."::\$$name");
    }


    /**
     * Returns the list of all enum variants
     * @return Array of Enum
     */
    static public function getList() {
        $className = get_called_class();
        return self::$list[$className];
    }


    private $name;
    private $value;

    public function __construct($name, $value) {
        $this->name = $name;
        $this->value = $value;
    }

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

    public function getValue() {
        return $this->value;
    }

    public function getName() {
        return $this->name;
    }

}

加成

您当然也可以为IDE添加注释

class Fruit extends Enum {

    /**
     * This comment is for autocomplete support in common IDEs
     * @var Fruit A yummy apple
     */
    static public $APPLE = 1;

    /**
     * This comment is for autocomplete support in common IDEs
     * @var Fruit A sour orange
     */
    static public $ORANGE = 2;
}

//This can also go to the autoloader if available.
Fruit::initialize();

4

我意识到这是一个非常非常古老的话题,但是我对此有所考虑,并且想知道人们的想法。

注意:我一直在处理这个问题,并且意识到,如果我只是修改该__call()函数,则可以更加接近real enums。该__call()函数处理所有未知的函数调用。假设您要制作三个enumsRED_LIGHT,YELLOW_LIGHT和GREEN_LIGHT。您现在只需执行以下操作即可:

$c->RED_LIGHT();
$c->YELLOW_LIGHT();
$c->GREEN_LIGHT();

定义后,您要做的就是再次调用它们以获取值:

echo $c->RED_LIGHT();
echo $c->YELLOW_LIGHT();
echo $c->GREEN_LIGHT();

您应该得到0、1和2。玩得开心!现在也可以在GitHub上找到。

更新:我已经做到了,所以现在都使用了__get()__set()函数。这些使您不必调用函数,除非您愿意。相反,现在您可以说:

$c->RED_LIGHT;
$c->YELLOW_LIGHT;
$c->GREEN_LIGHT;

用于创建和获取值。因为最初没有定义变量,所以__get()调用了该函数(因为未指定值),该函数将看到未在数组中进行输入。因此,它使该条目生效,为其分配给定的最后一个值加一个(+1),递增最后一个值变量,然后返回TRUE。如果设置值:

$c->RED_LIGHT = 85;

然后__set()调用该函数,然后将最后一个值设置为新值加上一个(+1)。因此,现在我们有了一个很好的枚举方法,可以即时创建它们。

<?php
################################################################################
#   Class ENUMS
#
#       Original code by Mark Manning.
#       Copyrighted (c) 2015 by Mark Manning.
#       All rights reserved.
#
#       This set of code is hereby placed into the free software universe
#       via the GNU greater license thus placing it under the Copyleft
#       rules and regulations with the following modifications:
#
#       1. You may use this work in any other work.  Commercial or otherwise.
#       2. You may make as much money as you can with it.
#       3. You owe me nothing except to give me a small blurb somewhere in
#           your program or maybe have pity on me and donate a dollar to
#           sim_sales@paypal.com.  :-)
#
#   Blurb:
#
#       PHP Class Enums by Mark Manning (markem-AT-sim1-DOT-us).
#       Used with permission.
#
#   Notes:
#
#       VIM formatting.  Set tabs to four(4) spaces.
#
################################################################################
class enums
{
    private $enums;
    private $clear_flag;
    private $last_value;

################################################################################
#   __construct(). Construction function.  Optionally pass in your enums.
################################################################################
function __construct()
{
    $this->enums = array();
    $this->clear_flag = false;
    $this->last_value = 0;

    if( func_num_args() > 0 ){
        return $this->put( func_get_args() );
        }

    return true;
}
################################################################################
#   put(). Insert one or more enums.
################################################################################
function put()
{
    $args = func_get_args();
#
#   Did they send us an array of enums?
#   Ex: $c->put( array( "a"=>0, "b"=>1,...) );
#   OR  $c->put( array( "a", "b", "c",... ) );
#
    if( is_array($args[0]) ){
#
#   Add them all in
#
        foreach( $args[0] as $k=>$v ){
#
#   Don't let them change it once it is set.
#   Remove the IF statement if you want to be able to modify the enums.
#
            if( !isset($this->enums[$k]) ){
#
#   If they sent an array of enums like this: "a","b","c",... then we have to
#   change that to be "A"=>#. Where "#" is the current count of the enums.
#
                if( is_numeric($k) ){
                    $this->enums[$v] = $this->last_value++;
                    }
#
#   Else - they sent "a"=>"A", "b"=>"B", "c"=>"C"...
#
                    else {
                        $this->last_value = $v + 1;
                        $this->enums[$k] = $v;
                        }
                }
            }
        }
#
#   Nope!  Did they just sent us one enum?
#
        else {
#
#   Is this just a default declaration?
#   Ex: $c->put( "a" );
#
            if( count($args) < 2 ){
#
#   Again - remove the IF statement if you want to be able to change the enums.
#
                if( !isset($this->enums[$args[0]]) ){
                    $this->enums[$args[0]] = $this->last_value++;
                    }
#
#   No - they sent us a regular enum
#   Ex: $c->put( "a", "This is the first enum" );
#
                    else {
#
#   Again - remove the IF statement if you want to be able to change the enums.
#
                        if( !isset($this->enums[$args[0]]) ){
                            $this->last_value = $args[1] + 1;
                            $this->enums[$args[0]] = $args[1];
                            }
                        }
                }
            }

    return true;
}
################################################################################
#   get(). Get one or more enums.
################################################################################
function get()
{
    $num = func_num_args();
    $args = func_get_args();
#
#   Is this an array of enums request? (ie: $c->get(array("a","b","c"...)) )
#
    if( is_array($args[0]) ){
        $ary = array();
        foreach( $args[0] as $k=>$v ){
            $ary[$v] = $this->enums[$v];
            }

        return $ary;
        }
#
#   Is it just ONE enum they want? (ie: $c->get("a") )
#
        else if( ($num > 0) && ($num < 2) ){
            return $this->enums[$args[0]];
            }
#
#   Is it a list of enums they want? (ie: $c->get( "a", "b", "c"...) )
#
        else if( $num > 1 ){
            $ary = array();
            foreach( $args as $k=>$v ){
                $ary[$v] = $this->enums[$v];
                }

            return $ary;
            }
#
#   They either sent something funky or nothing at all.
#
    return false;
}
################################################################################
#   clear(). Clear out the enum array.
#       Optional.  Set the flag in the __construct function.
#       After all, ENUMS are supposed to be constant.
################################################################################
function clear()
{
    if( $clear_flag ){
        unset( $this->enums );
        $this->enums = array();
        }

    return true;
}
################################################################################
#   __call().  In case someone tries to blow up the class.
################################################################################
function __call( $name, $arguments )
{
    if( isset($this->enums[$name]) ){ return $this->enums[$name]; }
        else if( !isset($this->enums[$name]) && (count($arguments) > 0) ){
            $this->last_value = $arguments[0] + 1;
            $this->enums[$name] = $arguments[0];
            return true;
            }
        else if( !isset($this->enums[$name]) && (count($arguments) < 1) ){
            $this->enums[$name] = $this->last_value++;
            return true;
            }

    return false;
}
################################################################################
#   __get(). Gets the value.
################################################################################
function __get($name)
{
    if( isset($this->enums[$name]) ){ return $this->enums[$name]; }
        else if( !isset($this->enums[$name]) ){
            $this->enums[$name] = $this->last_value++;
            return true;
            }

    return false;
}
################################################################################
#   __set().  Sets the value.
################################################################################
function __set( $name, $value=null )
{
    if( isset($this->enums[$name]) ){ return false; }
        else if( !isset($this->enums[$name]) && !is_null($value) ){
            $this->last_value = $value + 1;
            $this->enums[$name] = $value;
            return true;
            }
        else if( !isset($this->enums[$name]) && is_null($value) ){
            $this->enums[$name] = $this->last_value++;
            return true;
            }

    return false;
}
################################################################################
#   __destruct().  Deconstruct the class.  Remove the list of enums.
################################################################################
function __destruct()
{
    unset( $this->enums );
    $this->enums = null;

    return true;
}

}
#
#   Test code
#
#   $c = new enums();
#   $c->RED_LIGHT(85);
#   $c->YELLOW_LIGHT = 23;
#   $c->GREEN_LIGHT;
#
#   echo $c->RED_LIGHT . "\n";
#   echo $c->YELLOW_LIGHT . "\n";
#   echo $c->GREEN_LIGHT . "\n";

?>

3

我知道这是一个旧线程,但是我见过的任何变通方法都没有真正看起来像枚举,因为几乎所有变通方法都需要您手动将值分配给枚举项,或者它要求您将枚举键数组传递给功能。因此,我为此创建了自己的解决方案。

要使用我的解决方案创建一个枚举类,可以简单地在下面扩展此Enum类,创建一堆静态变量(无需初始化它们),然后在枚举类的定义下方调用yourEnumClass :: init() 。

编辑:这仅在php> = 5.3中有效,但也可以将其修改为在旧版本中工作

/**
 * 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;
                }
            }
        }
    }
}

3

现在,您可以使用SplEnum类本地构建它。根据官方文档。

SplEnum提供了在PHP中本地模拟和创建枚举对象的功能。

<?php
class Month extends SplEnum {
    const __default = self::January;

    const January = 1;
    const February = 2;
    const March = 3;
    const April = 4;
    const May = 5;
    const June = 6;
    const July = 7;
    const August = 8;
    const September = 9;
    const October = 10;
    const November = 11;
    const December = 12;
}

echo new Month(Month::June) . PHP_EOL;

try {
    new Month(13);
} catch (UnexpectedValueException $uve) {
    echo $uve->getMessage() . PHP_EOL;
}
?>

请注意,这是一个必须安装的扩展程序,但默认情况下不可用。它属于php网站本身中描述的特殊类型。上面的示例取自PHP网站。


3

最后,一个PHP 7.1+的常量不能被覆盖的答案。

/**
 * An interface that groups HTTP Accept: header Media Types in one place.
 */
interface MediaTypes
{
    /**
    * Now, if you have to use these same constants with another class, you can
    * without creating funky inheritance / is-a relationships.
    * Also, this gets around the single inheritance limitation.
    */

    public const HTML = 'text/html';
    public const JSON = 'application/json';
    public const XML = 'application/xml';
    public const TEXT = 'text/plain';
}

/**
 * An generic request class.
 */
abstract class Request
{
    // Why not put the constants here?
    // 1) The logical reuse issue.
    // 2) Single Inheritance. 
    // 3) Overriding is possible.

    // Why put class constants here?
    // 1) The constant value will not be necessary in other class families.
}

/**
 * An incoming / server-side HTTP request class.
 */
class HttpRequest extends Request implements MediaTypes
{
    // This class can implement groups of constants as necessary.
}

如果使用名称空间,则代码补全应该起作用。

但是,这样做会失去在类族(protected)或单独类()中隐藏常量的能力private。根据定义,中的所有内容Interface均为public

PHP手册:接口


这不是Java。这在不需要多态/策略模式来覆盖父类中的常量的情况下有效。
安东尼·鲁特里奇

2

这是我对“动态”枚举的看法...这样我就可以用变量来调用它,例如。从表单。

看看这个代码块下面的更新版本...

$value = "concert";
$Enumvalue = EnumCategory::enum($value);
//$EnumValue = 1

class EnumCategory{
    const concert = 1;
    const festival = 2;
    const sport = 3;
    const nightlife = 4;
    const theatre = 5;
    const musical = 6;
    const cinema = 7;
    const charity = 8;
    const museum = 9;
    const other = 10;

    public function enum($string){
        return constant('EnumCategory::'.$string);
    }
}

更新:更好的方法...

class EnumCategory {

    static $concert = 1;
    static $festival = 2;
    static $sport = 3;
    static $nightlife = 4;
    static $theatre = 5;
    static $musical = 6;
    static $cinema = 7;
    static $charity = 8;
    static $museum = 9;
    static $other = 10;

}

致电

EnumCategory::${$category};

5
问题在于:EnumCategory::$sport = 9;。欢迎来到体育博物馆。const 更好的方法。
Dan Lugg

2

可接受的答案是要走的路,实际上是我为简单起见所做的事情。提供了枚举的大多数优点(可读,快速等)。但是,缺少一个概念:类型安全。在大多数语言中,枚举也用于限制允许的值。下面是一个使用私有构造函数,静态实例化方法和类型检查如何获得类型安全的示例:

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

 private $intVal;
 private function __construct($intVal){
   $this->intVal = $intVal;
 }

 //static instantiation methods
 public static function MONDAY(){
   return new self(self::Monday);
 }
 //etc.
}

//function using type checking
function printDayOfWeek(DaysOfWeek $d){ //compiler can now use type checking
  // to something with $d...
}

//calling the function is safe!
printDayOfWeek(DaysOfWeek::MONDAY());

我们甚至可以走得更远:在DaysOfWeek类中使用常量可能会导致滥用:例如,一个人可能会以这种方式错误地使用它:

printDayOfWeek(DaysOfWeek::Monday); //triggers a compiler error.

这是错误的(调用整数常量)。我们可以使用私有静态变量而不是常量来防止这种情况:

class DaysOfWeeks{

  private static $monday = 1;
  //etc.

  private $intVal;
  //private constructor
  private function __construct($intVal){
    $this->intVal = $intVal;
  }

  //public instantiation methods
  public static function MONDAY(){
    return new self(self::$monday);
  }
  //etc.


  //convert an instance to its integer value
  public function intVal(){
    return $this->intVal;
  }

}

当然,不可能访问整数常量(这实际上是目的)。intVal方法允许将DaysOfWeek对象转换为其整数表示形式。

请注意,在广泛使用枚举的情况下,我们甚至可以通过在实例化方法中实现缓存机制来节省内存,从而进一步扩展...

希望这会有所帮助


2

这里有一些好的解决方案!

这是我的版本。

  • 它是强类型的
  • 它可与IDE自动补全一起使用
  • 枚举由代码和描述定义,其中代码可以是整数,二进制值,短字符串或基本上任何您想要的其他内容。该图案可以容易地扩展以支持其他特性。
  • 它支持值(==)和引用(===)比较,并在switch语句中起作用。

我认为主要的缺点是,由于描述以及PHP无法在静态成员声明时构造对象,因此枚举成员必须分别声明和实例化。我想这可能是将反射与已解析的文档注释一起使用。

抽象枚举看起来像这样:

<?php

abstract class AbstractEnum
{
    /** @var array cache of all enum instances by class name and integer value */
    private static $allEnumMembers = array();

    /** @var mixed */
    private $code;

    /** @var string */
    private $description;

    /**
     * Return an enum instance of the concrete type on which this static method is called, assuming an instance
     * exists for the passed in value.  Otherwise an exception is thrown.
     *
     * @param $code
     * @return AbstractEnum
     * @throws Exception
     */
    public static function getByCode($code)
    {
        $concreteMembers = &self::getConcreteMembers();

        if (array_key_exists($code, $concreteMembers)) {
            return $concreteMembers[$code];
        }

        throw new Exception("Value '$code' does not exist for enum '".get_called_class()."'");
    }

    public static function getAllMembers()
    {
        return self::getConcreteMembers();
    }

    /**
     * Create, cache and return an instance of the concrete enum type for the supplied primitive value.
     *
     * @param mixed $code code to uniquely identify this enum
     * @param string $description
     * @throws Exception
     * @return AbstractEnum
     */
    protected static function enum($code, $description)
    {
        $concreteMembers = &self::getConcreteMembers();

        if (array_key_exists($code, $concreteMembers)) {
            throw new Exception("Value '$code' has already been added to enum '".get_called_class()."'");
        }

        $concreteMembers[$code] = $concreteEnumInstance = new static($code, $description);

        return $concreteEnumInstance;
    }

    /**
     * @return AbstractEnum[]
     */
    private static function &getConcreteMembers() {
        $thisClassName = get_called_class();

        if (!array_key_exists($thisClassName, self::$allEnumMembers)) {
            $concreteMembers = array();
            self::$allEnumMembers[$thisClassName] = $concreteMembers;
        }

        return self::$allEnumMembers[$thisClassName];
    }

    private function __construct($code, $description)
    {
        $this->code = $code;
        $this->description = $description;
    }

    public function getCode()
    {
        return $this->code;
    }

    public function getDescription()
    {
        return $this->description;
    }
}

这是一个具体的枚举示例:

<?php

require('AbstractEnum.php');

class EMyEnum extends AbstractEnum
{
    /** @var EMyEnum */
    public static $MY_FIRST_VALUE;
    /** @var EMyEnum */
    public static $MY_SECOND_VALUE;
    /** @var EMyEnum */
    public static $MY_THIRD_VALUE;

    public static function _init()
    {
        self::$MY_FIRST_VALUE = self::enum(1, 'My first value');
        self::$MY_SECOND_VALUE = self::enum(2, 'My second value');
        self::$MY_THIRD_VALUE = self::enum(3, 'My third value');
    }
}

EMyEnum::_init();

可以这样使用:

<?php

require('EMyEnum.php');

echo EMyEnum::$MY_FIRST_VALUE->getCode().' : '.EMyEnum::$MY_FIRST_VALUE->getDescription().PHP_EOL.PHP_EOL;

var_dump(EMyEnum::getAllMembers());

echo PHP_EOL.EMyEnum::getByCode(2)->getDescription().PHP_EOL;

并产生以下输出:

1:我的第一个价值

array(3){
[1] =>
object(EMyEnum)#1(2){
[“代码”:“ AbstractEnum”:private] =>
int(1)
[“ description”:“ AbstractEnum”:private] =>
字符串(14)“我的第一个值”
}
[2] =>
object(EMyEnum)#2(2){
[“代码”:“ AbstractEnum”:private] =>
int(2)
[“ description”:“ AbstractEnum” :private] =>
字符串(15)“我的第二个值”
}
[3] =>
object(EMyEnum)#3(2){
[“” code“:” AbstractEnum“:private] =>
int(3)
[“ description”:“ AbstractEnum”:private] =>
string(14)“我的第三个值”
}
}

我的第二个价值


2
class DayOfWeek {
    static $values = array(
        self::MONDAY,
        self::TUESDAY,
        // ...
    );

    const MONDAY  = 0;
    const TUESDAY = 1;
    // ...
}

$today = DayOfWeek::MONDAY;

// If you want to check if a value is valid
assert( in_array( $today, DayOfWeek::$values ) );

不要使用反射。这使得很难对代码进行推理,并很难找到所使用的内容,并且往往会破坏静态分析工具(例如,IDE内置的工具)。


2

这里其他一些答案中缺少的一个方面是一种将枚举与类型提示一起使用的方法。

如果您将枚举定义为抽象类中的一组常量,例如

abstract class ShirtSize {
    public const SMALL = 1;
    public const MEDIUM = 2;
    public const LARGE = 3;
}

那么您就不能在函数参数中键入提示它-因为其中一个是不可实例化的,还因为它的类型ShirtSize::SMALLint,不是ShirtSize

这就是为什么PHP中的本机枚举要比我们能想到的任何东西都要好得多的原因。但是,我们可以通过保留代表枚举值的私有属性来近似枚举,然后将该属性的初始化限制为我们预定义的常量。为了防止枚举被任意实例化(不进行白名单类型检查的开销),我们将构造函数设为私有。

class ShirtSize {
    private $size;
    private function __construct ($size) {
        $this->size = $size;
    }
    public function equals (ShirtSize $s) {
        return $this->size === $s->size;
    }
    public static function SMALL () { return new self(1); }
    public static function MEDIUM () { return new self(2); }
    public static function LARGE () { return new self(3); }
}

然后我们可以这样使用ShirtSize

function sizeIsAvailable ($productId, ShirtSize $size) {
    // business magic
}
if(sizeIsAvailable($_GET["id"], ShirtSize::LARGE())) {
    echo "Available";
} else {
    echo "Out of stock.";
}
$s2 = ShirtSize::SMALL();
$s3 = ShirtSize::MEDIUM();
echo $s2->equals($s3) ? "SMALL == MEDIUM" : "SMALL != MEDIUM";

这样,从用户的角度来看,最大的不同就是您必须()在常量的名称上加上“ a ”。

但是有一个缺点是===(比较对象相等性)当==返回true 时将返回false 。因此,最好提供一种equals方法,以使用户不必记住使用==而不是===比较两个枚举值。

编辑:几个现有的答案非常相似,特别是:https : //stackoverflow.com/a/25526473/2407870


2

踩着@Brian Cline的答案,我想我可以给我5美分

<?php 
/**
 * A class that simulates Enums behaviour
 * <code>
 * class Season extends Enum{
 *    const Spring  = 0;
 *    const Summer = 1;
 *    const Autumn = 2;
 *    const Winter = 3;
 * }
 * 
 * $currentSeason = new Season(Season::Spring);
 * $nextYearSeason = new Season(Season::Spring);
 * $winter = new Season(Season::Winter);
 * $whatever = new Season(-1);               // Throws InvalidArgumentException
 * echo $currentSeason.is(Season::Spring);   // True
 * echo $currentSeason.getName();            // 'Spring'
 * echo $currentSeason.is($nextYearSeason);  // True
 * echo $currentSeason.is(Season::Winter);   // False
 * echo $currentSeason.is(Season::Spring);   // True
 * echo $currentSeason.is($winter);          // False
 * </code>
 * 
 * Class Enum
 * 
 * PHP Version 5.5
 */
abstract class Enum
{
    /**
     * Will contain all the constants of every enum that gets created to 
     * avoid expensive ReflectionClass usage
     * @var array
     */
    private static $_constCacheArray = [];
    /**
     * The value that separates this instance from the rest of the same class
     * @var mixed
     */
    private $_value;
    /**
     * The label of the Enum instance. Will take the string name of the 
     * constant provided, used for logging and human readable messages
     * @var string
     */
    private $_name;
    /**
     * Creates an enum instance, while makes sure that the value given to the 
     * enum is a valid one
     * 
     * @param mixed $value The value of the current
     * 
     * @throws \InvalidArgumentException
     */
    public final function __construct($value)
    {
        $constants = self::_getConstants();
        if (count($constants) !== count(array_unique($constants))) {
            throw new \InvalidArgumentException('Enums cannot contain duplicate constant values');
        }
        if ($name = array_search($value, $constants)) {
            $this->_value = $value;
            $this->_name = $name;
        } else {
            throw new \InvalidArgumentException('Invalid enum value provided');
        }
    }
    /**
     * Returns the constant name of the current enum instance
     * 
     * @return string
     */
    public function getName()
    {
        return $this->_name;
    }
    /**
     * Returns the value of the current enum instance
     * 
     * @return mixed
     */
    public function getValue()
    {
        return $this->_value;
    }
    /**
     * Checks whether this enum instance matches with the provided one.
     * This function should be used to compare Enums at all times instead
     * of an identity comparison 
     * <code>
     * // Assuming EnumObject and EnumObject2 both extend the Enum class
     * // and constants with such values are defined
     * $var  = new EnumObject('test'); 
     * $var2 = new EnumObject('test');
     * $var3 = new EnumObject2('test');
     * $var4 = new EnumObject2('test2');
     * echo $var->is($var2);  // true
     * echo $var->is('test'); // true
     * echo $var->is($var3);  // false
     * echo $var3->is($var4); // false
     * </code>
     * 
     * @param mixed|Enum $enum The value we are comparing this enum object against
     *                         If the value is instance of the Enum class makes
     *                         sure they are instances of the same class as well, 
     *                         otherwise just ensures they have the same value
     * 
     * @return bool
     */
    public final function is($enum)
    {
        // If we are comparing enums, just make
        // sure they have the same toString value
        if (is_subclass_of($enum, __CLASS__)) {
            return get_class($this) === get_class($enum) 
                    && $this->getValue() === $enum->getValue();
        } else {
            // Otherwise assume $enum is the value we are comparing against
            // and do an exact comparison
            return $this->getValue() === $enum;   
        }
    }

    /**
     * Returns the constants that are set for the current Enum instance
     * 
     * @return array
     */
    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];
    }
}

由于某些原因,我无法称呼此功能。它告诉我未声明此类功能。我做错了什么?[基本Enum类位于另一个文件中,我正在使用include('enums.php');]。由于某种原因,它看不到在Enum中为子类声明的函数...
Andrew

另外...如何从字符串设置它?像$currentSeason.set("Spring");
安德鲁(Andrew)

1

我试图用PHP创建一个枚举...这是非常有限的,因为它不支持将对象用作枚举值,但仍然有些用处...

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();
    }
}

它在许多方面都受到限制,现有的答案远远超出了它。我会说这并没有真正添加任何有用的东西。
hakre 2012年

1

昨天我在博客上写了这个课。我认为在php脚本中使用起来可能很容易:

final class EnumException extends Exception{}

abstract class Enum
{
    /**
     * @var array ReflectionClass
     */
    protected static $reflectorInstances = array();
    /**
     * Массив конфигурированного объекта-константы enum
     * @var array
     */
    protected static $enumInstances = array();
    /**
     * Массив соответствий значение->ключ используется для проверки - 
     * если ли константа с таким значением
     * @var array
     */
    protected static $foundNameValueLink = array();

    protected $constName;
    protected $constValue;

    /**
     * Реализует паттерн "Одиночка"
     * Возвращает объект константы, но но как объект его использовать не стоит, 
     * т.к. для него реализован "волшебный метод" __toString()
     * Это должно использоваться только для типизачии его как параметра
     * @paradm Node
     */
    final public static function get($value)
    {
        // Это остается здесь для увеличения производительности (по замерам ~10%)
        $name = self::getName($value);
        if ($name === false)
            throw new EnumException("Неизвестая константа");
        $className = get_called_class();    
        if (!isset(self::$enumInstances[$className][$name]))
        {
            $value = constant($className.'::'.$name);
            self::$enumInstances[$className][$name] = new $className($name, $value);
        }

        return self::$enumInstances[$className][$name];
    }

    /**
     * Возвращает массив констант пар ключ-значение всего перечисления
     * @return array 
     */
    final public static function toArray()
    {
        $classConstantsArray = self::getReflectorInstance()->getConstants();
        foreach ($classConstantsArray as $k => $v)
            $classConstantsArray[$k] = (string)$v;
        return $classConstantsArray;
    }

    /**
     * Для последующего использования в toArray для получения массива констант ключ->значение 
     * @return ReflectionClass
     */
    final private static function getReflectorInstance()
    {
        $className = get_called_class();
        if (!isset(self::$reflectorInstances[$className]))
        {
            self::$reflectorInstances[$className] = new ReflectionClass($className);
        }
        return self::$reflectorInstances[$className];
    }

    /**
     * Получает имя константы по её значению
     * @param string $value
     */
    final public static function getName($value)
    {
        $className = (string)get_called_class();

        $value = (string)$value;
        if (!isset(self::$foundNameValueLink[$className][$value]))
        {
            $constantName = array_search($value, self::toArray(), true);
            self::$foundNameValueLink[$className][$value] = $constantName;
        }
        return self::$foundNameValueLink[$className][$value];
    }

    /**
     * Используется ли такое имя константы в перечислении
     * @param string $name
     */
    final public static function isExistName($name)
    {
        $constArray = self::toArray();
        return isset($constArray[$name]);
    }

    /**
     * Используется ли такое значение константы в перечислении
     * @param string $value
     */
    final public static function isExistValue($value)
    {
        return self::getName($value) === false ? false : true;
    }   


    final private function __clone(){}

    final private function __construct($name, $value)
    {
        $this->constName = $name;
        $this->constValue = $value;
    }

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

用法:

class enumWorkType extends Enum
{
        const FULL = 0;
        const SHORT = 1;
}

2
但这是很好的类,函数名称是本机的。并可能还会对translate.google.ru有所帮助。
Arturgspb 2011年

2
如果您是程序员,请使用chrome并进行翻译,然后阅读代码!
markus

8
一般情况下,它总是更好地包括了答案中的代码,而不是链接到外部资源,可能会或可能不会出现在“N”个月/年等
约翰·帕克

我的班级很大,我认为阅读这篇文章会很不方便。
Arturgspb 2011年

我认为这有两点不好:它是俄语的(每个程序员都必须懂英语,甚至在注释中也要使用它)&这里不包括它。请参阅帮助,了解如何包含大量代码。
gaRex 2012年
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