我知道PHP还没有本地枚举。但是我已经习惯了来自Java世界的它们。我喜欢使用枚举来提供ide的自动补全功能能够理解的预定义值。

常量可以解决这个问题,但是存在名称空间冲突问题,而且(实际上是因为)它们是全局的。数组没有名称空间的问题,但是它们太模糊了,它们可以在运行时被覆盖,而且ide很少知道如何在没有额外的静态分析注释或属性的情况下自动填充它们的键。

你有什么常用的解决方案/变通办法吗?有人记得PHP的人对枚举有什么想法或决定吗?


当前回答

一个不使用反射的更简单、更轻的版本:

abstract class enum {
    private function __construct() {}
    static function has($const) {
        $name = get_called_class();
        return defined("$name::$const");
    }
    static function value($const) {
        $name = get_called_class();
        return defined("$name::$const")? constant("$name::$const") : false;
    }
}

用法:

class requestFormat  extends enum { const HTML = 1; const JSON = 2; const XML  = 3; const FORM = 4; }

echo requestFormat::value('JSON'); // 2
echo requestFormat::has('JSON');   // true

这提供了常量的优势,也允许检查它们的有效性,但它缺乏更复杂的解决方案所提供的其他花哨功能,更明显的是无法检查值的反向(在上面的例子中,你不能检查'2'是否是一个有效值)

其他回答

如果您需要使用全局唯一的enum(即即使在不同enum之间比较元素时)并且易于使用,请随意使用以下代码。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";
    }

}


?>

还有一个本地扩展。的SplEnum

脾提供了模拟和创建枚举对象的能力 原生的PHP。

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

注意:

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

PECL扩展没有与PHP绑定。 此PECL扩展的DLL目前不可用。

这是我对“动态”enum的看法…这样我就可以用变量来调用它,比如从表单中。

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:更好的方式做…

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;

}

电话

EnumCategory::${$category};
// My Enumeration Class
class Enum
{
    protected $m_actions = array();

    public function __construct($actions)
    {
        $this->init($actions);
    }

    public function init($actions)
    {
        $this->m_actions = array();
        for($i = 0; $i < count($actions); ++$i)
        {
            $this->m_actions[$actions[$i]] = ($i + 1); 
            define($actions[$i], ($i + 1));
        }
    }

    public function toString($index)
    {
        $keys = array_keys($this->m_actions);
        for($i = 0; $i < count($keys); ++$i)
        {
            if($this->m_actions[$keys[$i]] == $index)
            {
                return $keys[$i];
            }
        }

        return "undefined";
    }

    public function fromString($str)
    {
        return $this->m_actions[$str];
    }
}

// Enumeration creation
$actions = new Enum(array("CREATE", "READ", "UPDATE", "DELETE"));

// Examples
print($action_objects->toString(DELETE));
print($action_objects->fromString("DELETE"));

if($action_objects->fromString($_POST["myAction"]) == CREATE)
{
    print("CREATE");
}

昨天我在博客上写了这门课。我认为在php脚本中使用它可能很容易:

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;
}