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
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
其他回答
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
在PHP 8.1中,您可以使用本机枚举。
基本语法如下所示:
enum TransportMode {
case Bicycle;
case Car;
case Ship;
case Plane;
case Feet;
}
function travelCost(TransportMode $mode, int $distance): int
{ /* implementation */ }
$mode = TransportMode::Boat;
$bikeCost = travelCost(TransportMode::Bicycle, 90);
$boatCost = travelCost($mode, 90);
// this one would fail: (Enums are singletons, not scalars)
$failCost = travelCost('Car', 90);
值
默认情况下,枚举不受任何类型的标量支持。因此TransportMode::Bicycle不是0,您不能在枚举之间使用>或<进行比较。
但以下方法是可行的:
$foo = TransportMode::Car;
$bar = TransportMode::Car;
$baz = TransportMode::Bicycle;
$foo === $bar; // true
$bar === $baz; // false
$foo instanceof TransportMode; // true
$foo > $bar || $foo < $bar; // false either way
支持枚举
你也可以有“支持的”枚举,其中每个枚举案例都由一个int或字符串“支持”。
enum Metal: int {
case Gold = 1932;
case Silver = 1049;
case Lead = 1134;
case Uranium = 1905;
case Copper = 894;
}
如果一个案例有一个支持值,所有案例都需要有一个支持值,没有自动生成的值。 注意,受支持值的类型声明在枚举名称之后 备份值为只读 标量值必须是唯一的 值必须是字面量或字面表达式 要读取支持的值,您可以访问value属性:Metal::Gold->value。
最后,被支持的枚举在内部实现了backdenum接口,它公开了两个方法:
从字符串(int |):自我 tryFrom (int |字符串):自我?
它们几乎是等效的,重要的区别是,如果没有找到值,第一个将抛出异常,而第二个将简单地返回null。
// usage example:
$metal_1 = Metal::tryFrom(1932); // $metal_1 === Metal::Gold;
$metal_2 = Metal::tryFrom(1000); // $metal_2 === null;
$metal_3 = Metal::from(9999); // throws Exception
方法
枚举可以有方法,从而实现接口。
interface TravelCapable
{
public function travelCost(int $distance): int;
public function requiresFuel(): bool;
}
enum TransportMode: int implements TravelCapable{
case Bicycle = 10;
case Car = 1000 ;
case Ship = 800 ;
case Plane = 2000;
case Feet = 5;
public function travelCost(int $distance): int
{
return $this->value * $distance;
}
public function requiresFuel(): bool {
return match($this) {
TransportMode::Car, TransportMode::Ship, TransportMode::Plane => true,
TransportMode::Bicycle, TransportMode::Feet => false
}
}
}
$mode = TransportMode::Car;
$carConsumesFuel = $mode->requiresFuel(); // true
$carTravelCost = $mode->travelCost(800); // 800000
值清单
Pure Enums和Backed Enums都在内部实现了接口UnitEnum,其中包括(静态)方法UnitEnum::cases(),并允许检索枚举中定义的案例数组:
$modes = TransportMode::cases();
现在$modes是:
[
TransportMode::Bicycle,
TransportMode::Car,
TransportMode::Ship,
TransportMode::Plane
TransportMode::Feet
]
静态方法
枚举可以实现自己的静态方法,这些方法通常用于专门的构造函数。
这涵盖了基本知识。要了解全部内容,请前往相关RFC,直到该特性在PHP文档中发布。
我知道这是一个非常非常非常古老的话题,但我对此有一个想法,想知道人们是怎么想的。
注:我在玩这个,并意识到如果我只是修改__call()函数,你可以更接近实际的枚举。__call()函数处理所有未知函数调用。假设你想创建三个枚举RED_LIGHT, YELLOW_LIGHT和GREEN_LIGHT。你现在只需做以下事情就可以做到:
$c->RED_LIGHT();
$c->YELLOW_LIGHT();
$c->GREEN_LIGHT();
一旦定义了,你所要做的就是再次调用它们来获取值:
echo $c->RED_LIGHT();
echo $c->YELLOW_LIGHT();
echo $c->GREEN_LIGHT();
得到0 1 2。玩得开心!这个现在也在GitHub上。
更新:我已经这样做了,所以__get()和__set()函数现在都被使用。这允许您不必调用函数,除非您愿意。相反,现在你可以说:
$c->RED_LIGHT;
$c->YELLOW_LIGHT;
$c->GREEN_LIGHT;
对于价值的创造和获取。因为变量最初还没有定义,所以调用__get()函数(因为没有指定值),它会发现数组中的条目还没有创建。因此,它创建条目,将最后一个给定值赋给它+1(+1),对最后一个值变量加1,并返回TRUE。如果你设置这个值:
$c->RED_LIGHT = 85;
然后调用__set()函数,最后一个值被设置为新值+1(+1)。现在我们有了一个很好的方法来处理枚举,并且可以动态地创建它们。
<?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";
?>
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。