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?
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
我所见过的PHP中枚举最常见的解决方案是创建一个通用枚举类,然后扩展它。你可以看看这个。
更新:或者,我从phpclasses.org找到了这个。
其他回答
这可能很简单
enum DaysOfWeek {
Sunday,
Monday,
// ...
}
在未来。
枚举类型
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;
}
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 = $item+1; } } } } }
最后,PHP 7.1+给出了一个不能被重写的常量。
/**
* An interface that groups HTTP Accept: header Media Types in one place.
*/
interface MediaTypes
{
/**
* Now, if you have to use these same constants with another class, you can
* without creating funky inheritance / is-a relationships.
* Also, this gets around the single inheritance limitation.
*/
public const HTML = 'text/html';
public const JSON = 'application/json';
public const XML = 'application/xml';
public const TEXT = 'text/plain';
}
/**
* An generic request class.
*/
abstract class Request
{
// Why not put the constants here?
// 1) The logical reuse issue.
// 2) Single Inheritance.
// 3) Overriding is possible.
// Why put class constants here?
// 1) The constant value will not be necessary in other class families.
}
/**
* An incoming / server-side HTTP request class.
*/
class HttpRequest extends Request implements MediaTypes
{
// This class can implement groups of constants as necessary.
}
如果您使用的是名称空间,那么代码补全应该可以工作。
但是,这样做将失去在类族(protected)或单独在类(private)中隐藏常量的能力。根据定义,接口中的所有内容都是公共的。
PHP手册:接口
更新:
PHP 8.1现在有了枚举。
我已经在这里评论了一些其他的答案,所以我想我也会发表意见。 最后,由于PHP不支持类型化枚举,您可以选择以下两种方式之一:删除类型化枚举,或者接受它们极难有效删除的事实。
我更倾向于接受事实,而不是使用其他答案以某种方式使用的const方法:
abstract class Enum
{
const NONE = null;
final private function __construct()
{
throw new NotSupportedException(); //
}
final private function __clone()
{
throw new NotSupportedException();
}
final public static function toArray()
{
return (new ReflectionClass(static::class))->getConstants();
}
final public static function isValid($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