PHP中Enum(枚举)用法实例详解
发布:smiling 来源: PHP粉丝网 添加日期:2021-06-29 09:53:29 浏览: 评论:0
这篇文章主要介绍了PHP中Enum(枚举)用法,结合实例形式较为详细的分析了php中Enum(枚举)的实现与使用技巧,具有一定参考借鉴价值,需要的朋友可以参考下。
本文实例讲述了PHP中Enum(枚举)用法。分享给大家供大家参考,具体如下:
PHP其实有Enum类库的,需要安装perl扩展,所以不是php的标准扩展,因此代码的实现需要运行的php环境支持。
(1)扩展类库SplEnum类。该类的摘要如下:
- SplEnum extends SplType {
- /* Constants */
- const NULL __default = null ;
- /* 方法 */
- public array getConstList ([ bool $include_default = false ] )
- /* 继承的方法 */
- SplType::__construct ([ mixed $initial_value [, bool $strict ]] )
- }
使用示例:
- <?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;
- }
- ?>
输出结果:
Value not a const in enum Month
(2)自定义的Enum类库
- <?php
- /**
- * Abstract class that enables creation of PHP enums. All you
- * have to do is extend this class and define some constants.
- * Enum is an object with value from on of those constants
- * (or from on of superclass if any). There is also
- * __default constat that enables you creation of object
- * without passing enum value.
- *
- * @author Marijan Šuflaj <msufflaj32@gmail.com>
- * @link http://php4every1.com
- */
- abstract class Enum {
- /**
- * Constant with default value for creating enum object
- */
- const __default = null;
- private $value;
- private $strict;
- private static $constants = array();
- /**
- * Returns list of all defined constants in enum class.
- * Constants value are enum values.
- *
- * @param bool $includeDefault If true, default value is included into return
- * @return array Array with constant values
- */
- public function getConstList($includeDefault = false) {
- $class = get_class($this);
- if (!array_key_exists($class, self::$constants)) {
- self::populateConstants();
- }
- return $includeDefault ? array_merge(self::$constants[__CLASS_], array(
- "__default" => self::__default
- )) : self::$constants[__CLASS_];
- }
- /**
- * Creates new enum object. If child class overrides __construct(),
- * it is required to call parent::__construct() in order for this
- * class to work as expected.
- *
- * @param mixed $initialValue Any value that is exists in defined constants
- * @param bool $strict If set to true, type and value must be equal
- * @throws UnexpectedValueException If value is not valid enum value
- */
- public function __construct($initialValue = null, $strict = true) {
- $class = get_class($this);
- if (!array_key_exists($class, self::$constants)) {
- self::populateConstants();
- }
- if ($initialValue === null) {
- $initialValue = self::$constants[$class]["__default"];
- }
- $temp = self::$constants[$class];
- if (!in_array($initialValue, $temp, $strict)) {
- throw new UnexpectedValueException("Value is not in enum " . $class);
- }
- $this->value = $initialValue;
- $this->strict = $strict;
- }
- private function populateConstants() {
- $class = get_class($this);
- $r = new ReflectionClass($class);
- $constants = $r->getConstants();
- self::$constants = array(
- $class => $constants
- );
- }
- /**
- * Returns string representation of an enum. Defaults to
- * value casted to string.
- *
- * @return string String representation of this enum's value
- */
- public function __toString() {
- return (string) $this->value;
- }
- /**
- * Checks if two enums are equal. Only value is checked, not class type also.
- * If enum was created with $strict = true, then strict comparison applies
- * here also.
- *
- * @return bool True if enums are equal
- */
- public function equals($object) {
- if (!($object instanceof Enum)) {
- return false;
- }
- return $this->strict ? ($this->value === $object->value)
- : ($this->value == $object->value);
- }
- }
使用示例如下:
- class MyEnum extends Enum {
- const HI = "Hi";
- const BY = "By";
- const NUMBER = 1;
- const __default = self::BY;
- }
- var_dump(new MyEnum(MyEnum::HI));
- var_dump(new MyEnum(MyEnum::BY));
- //Use __default
- var_dump(new MyEnum());
- try {
- new MyEnum("I don't exist");
- } catch (UnexpectedValueException $e) {
- var_dump($e->getMessage());
- }
输出结果如下:
- object(MyEnum)#1 (2) {
- ["value":"Enum":private]=>
- string(2) "Hi"
- ["strict":"Enum":private]=>
- bool(true)
- }
- object(MyEnum)#1 (2) {
- ["value":"Enum":private]=>
- string(2) "By"
- ["strict":"Enum":private]=>
- bool(true)
- }
- object(MyEnum)#1 (2) {
- ["value":"Enum":private]=>
- string(2) "By"
- ["strict":"Enum":private]=>
- bool(true)
- }
- string(27) "Value is not in enum MyEnum"
希望本文所述对大家PHP程序设计有所帮助。
Tags: Enum PHP枚举
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