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
上面的答案太棒了。但是,如果以两种不同的方式进行扩展,那么无论先进行哪种扩展,都会导致对函数的调用,从而创建缓存。这个缓存将被所有后续调用使用,无论调用是由哪个扩展发起的…
要解决这个问题,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];
}
其他回答
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
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。这使得你很难推断你的代码并追踪某些东西被使用的位置,而且往往会破坏静态分析工具(例如你的IDE中内置的工具)。
下面是一个github库,用于在php中处理类型安全的枚举:
这个库处理类生成、类缓存,并实现了Type Safe Enumeration设计模式,使用几个辅助方法来处理枚举,比如为枚举排序检索序号,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。
它是由phpunit覆盖的完整测试。
Php-enums在github (feel free to fork)
用法:(@参见Usage .php或单元测试了解更多细节)
<?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
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;
}
提出的解决方案效果很好。干净光滑。
然而,如果你想要强类型的枚举,你可以使用这个:
class TestEnum extends Enum
{
public static $TEST1;
public static $TEST2;
}
TestEnum::init(); // Automatically initializes enum values
枚举类如下所示:
class Enum
{
public static function parse($enum)
{
$class = get_called_class();
$vars = get_class_vars($class);
if (array_key_exists($enum, $vars)) {
return $vars[$enum];
}
return null;
}
public static function init()
{
$className = get_called_class();
$consts = get_class_vars($className);
foreach ($consts as $constant => $value) {
if (is_null($className::$$constant)) {
$constantValue = $constant;
$constantValueName = $className . '::' . $constant . '_VALUE';
if (defined($constantValueName)) {
$constantValue = constant($constantValueName);
}
$className::$$constant = new $className($constantValue);
}
}
}
public function __construct($value)
{
$this->value = $value;
}
}
这样,枚举值是强类型的和
$TEST1 == TEST1::parse('TEST1') // true语句