PHP - Manual: SplEnum

2024-12-26

SplEnum::getConstList »

« SplFloat

The SplEnum class

(PECL spl_types >= 0.1.0)

简介

SplEnum gives the ability to emulate and create enumeration objects natively in PHP.

类摘要

SplEnum extends SplType {

/* Constants */

const NULL __default = NULL ;

/* 方法 */

public getConstList ([ bool $include_default = FALSE ] ) : array

/* 继承的方法 */

SplType::__construct ([ mixed $initial_value [, bool $strict ]] )

}

预定义常量

SplEnum::__default

范例

Example #1 SplEnum usage example


<?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;
}
?>

以上例程会输出：

6
Value not a const in enum Month

SplEnum::getConstList — Returns all consts (possible values) as an array

add a note

User Contributed Notes 5 notes

down

mohanrajnr at gmail dot com ¶

4 years ago


Source: https://stackoverflow.com/a/254543/508666



if class SplEnum is not present, I would normally use something simple like the following:



abstract class DaysOfWeek

{

    const Sunday = 0;

    const Monday = 1;

    // etc.

}



$today = DaysOfWeek::Sunday;

However, other use cases may require more validation of constants and values. 



abstract class BasicEnum {

    private static $constCacheArray = NULL;



private function __construct(){

      /*

        Preventing instance :)

      */

     }



    private static function getConstants() {

        if (self::$constCacheArray == NULL) {

            self::$constCacheArray = [];

        }

        $calledClass = get_called_class();

        if (!array_key_exists($calledClass, self::$constCacheArray)) {

            $reflect = new ReflectionClass($calledClass);

            self::$constCacheArray[$calledClass] = $reflect->getConstants();

        }

        return self::$constCacheArray[$calledClass];

    }



    public static function isValidName($name, $strict = false) {

        $constants = self::getConstants();



        if ($strict) {

            return array_key_exists($name, $constants);

        }



        $keys = array_map('strtolower', array_keys($constants));

        return in_array(strtolower($name), $keys);

    }



    public static function isValidValue($value) {

        $values = array_values(self::getConstants());

        return in_array($value, $values, $strict = true);

    }

}

By creating a simple enum class that extends BasicEnum, you now have the ability to use methods thusly for simple input validation:



abstract class DaysOfWeek extends BasicEnum {

    const Sunday = 0;

    const Monday = 1;

    const Tuesday = 2;

    const Wednesday = 3;

    const Thursday = 4;

    const Friday = 5;

    const Saturday = 6;

}



DaysOfWeek::isValidName('Humpday');                  // false

DaysOfWeek::isValidName('Monday');                   // true

DaysOfWeek::isValidName('monday');                   // true

DaysOfWeek::isValidName('monday', $strict = true);   // false

DaysOfWeek::isValidName(0);                          // false



DaysOfWeek::isValidValue(0);                         // true

DaysOfWeek::isValidValue(5);                         // true

DaysOfWeek::isValidValue(7);                         // false

DaysOfWeek::isValidValue('Friday');                  // false

As a side note, any time I use reflection at least once on a static/const class where the data won't change (such as in an enum), I cache the results of those reflection calls, since using fresh reflection objects each time will eventually have a noticeable performance impact (Stored in an assocciative array for multiple enums).

down

No Such Alias ¶

8 years ago


Here's a clearer example usage in case anyone else finds the
current documentation confusing (as I did).

<?php
class Fruit extends SplEnum
{
  // If no value is given during object construction this value is used
  const __default = 1;
  // Our enum values
  const APPLE     = 1;
  const ORANGE    = 2;
}

$myApple   = new Fruit();
$myOrange  = new Fruit(Fruit::ORANGE);
$fail      = 1;

function eat(Fruit $aFruit)
{
  if (Fruit::APPLE == $aFruit) {
    echo "Eating an apple.\n";
  } elseif (Fruit::ORANGE == $aFruit) {
    echo "Eating an orange.\n";
  }
}

eat($myApple);  // Eating an apple.
eat($myOrange); // Eating an orange.

eat($fail); // PHP Catchable fatal error:  Argument 1 passed to eat() must be an instance of Fruit, integer given

?>

down

lsloan-php dot net at umich dot edu ¶

4 years ago


SplEnum is a nice start for enumerated type support as an extension (making enum a part of the language would be much better), but it lacks a lot of features that enums have in other languages.  I needed functionality like the hasKey() method supported by Java.  I extended the class as SplEnumPlus and used that subclass in my code as follows:

<?php
class SplEnumPlus extends SplEnum {
    static function hasKey($key) {
        $foundKey = false;
        
        try {
            $enumClassName = get_called_class();
            new $enumClassName($key);
            $foundKey = true;
        } finally {
            return $foundKey;
        }
    }
}

class Fruit extends SplEnumPlus {
  const APPLE     = 1;
  const ORANGE    = 2;
}

echo (Fruit::hasKey(Fruit::APPLE) ? 'yes' : 'no') . PHP_EOL; // yes
echo (Fruit::hasKey('banana') ? 'yes' : 'no') . PHP_EOL; // no
?>

Other useful features, like reverse value-to-key lookups, could be done in this way.  It would be helpful if this and other useful functionality were made part of SplEnum.

down

liebn0r ¶

1 year ago


Stylistically, SplEnum kind of sucks in use. Take for example, the following:

<?php

class Animal extends SplType {
    const MONKEY = 1;
    const HORSE = 2;
}

function putOnBoat( Animal $animal ) {
    // ...
}

putOnBoat( new Animal( Animal::MONKEY) );

?>

A little redundant, right? Here's a little extra stylistic step you can take to make usage a little cleaner.

<?php

class Animal extends SplType {

    const TYPE_MONKEY = 1;
    const TYPE_HORSE = 2;

    static $MONKEY;
    static $HORSE;

}

Animal::$MONKEY = new Animal( Animal::TYPE_MONKEY );
Animal::$HORSE = new Animal( Animal::TYPE_HORSE);

function putOnBoat( Animal $animal ) {
    // ...
}

putOnBoat( Animal::$MONKEY );

?>

down

-3

dc at dcitservices dot com dot au ¶

3 years ago


I use the following function getValue() to have a dynamically way to check and retrieve value without errors. 

class MyEnum extends SplEnum
{
    const __default = 0;

    const C1 = 1;
    const C2 = 2;

    public function getValue($key)
    {
        $declaredElems = $this->getConstList();
        if(array_key_exists($key, $declaredElems)){
            $r = new \ReflectionClass($this);
            return $r->getConstant($key);
        }else{
            return self::__default;
        }
    }
}

add a note

官方地址：https://www.php.net/manual/en/class.splenum.php

有任何技术问题请点击这里网站运营推广招聘

IT PHP 编程语言 Linux 开发编程科技 Elasticsearch HTML/CSS/XML 网络数据库面试 JAVA NoSQL C/C++ Golang Git 算法操作系统正则表达式 Redis 互联网 MySql JavaScript 运维软件国际架构设计 Mac OS TCP/IP Excel Vim Windows Socket Oracle VR MongoDB Python 运营 MemCache 商业硬件电子娱乐设计 nginx 摄影游戏 WordPress HTTP 团建数码电器

php7 安装fileinfo扩展 preg_split — 通过一个正则表达式分隔字符串 php位值,解决 PHP 中 usort 在值相同时改变原始位置的问题 [PHP] inet_pton/inet_ntop IP地址转换函数 PHP 8.1 [鸟哥]PHP_INT_MIN 和 -9223372036854775808 ADORecordSet对象 adodb手册 opcache预加载 Composer的Packagist资源 mysql面试题 array_multisort() 多字段排序 PHP json解析（json_decode）页面工具 php中几种注释规范 PHP5 扩展SOAP 调用 webservice PHPMailer设置utf8 PHPMailer字符集CharSet php扩展开发 PHP获取指定函数定义在哪个文件中及行号利用PHP SOAP实现WEB SERVICE 支持php7的性能采集扩展

略微加速

PHP官方手册 - 互联网笔记

The SplEnum class

简介

类摘要

预定义常量

范例

Table of Contents

User Contributed Notes 5 notes