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
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};
其他回答
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; } } } } }
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
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";
}
}
?>
现在您可以使用The脾脏类来原生构建它。根据官方文件。
脾提供了模拟和创建枚举对象的能力 原生的PHP。
<?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,但默认情况下不可用。在PHP网站上描述的特殊类型下。上面的示例取自PHP站点。