PHP 枚举类型的管理与设计

const YES = ‘是‘;
const NO = ‘否‘;

class BoolEnum {
    const YES = ‘是‘;
    const NO = ‘否‘;
}

BoolEnum::YES(); // 是
BoolEnum::NO(); // 否

BoolEnum::toArray(); // [‘Yes‘ => ‘是‘, ‘No‘ => ‘否‘]

abstract class Enum
{   
    // 获取所有枚举类型
    public static function toArray(){

        // 通过反射获取常量
        $reflection = new \ReflectionClass(static::class);
        $contants = $reflection->getConstants();

        // 返回对应的常量
        return $contants;
    }

    //  动态调用属性
    public static function __callStatic($name, $arguments)
    {
        $arr = static::toArray();

        if(isset($arr[$name])){
            return $arr[$name];
        }

        throw new \BadMethodCallException("找不到对应的枚举值 {$name}");
    }
}

class BoolEnum extends Enum
{
    const YES = ‘是‘;
    const NO = ‘否‘;
}

abstract class Enum
{   
    protected static $cache = [];

    public static function toArray(){

        $class = static::class;

        // 第一次获取，就通过反射来获取
        if(! isset(static::$cache[$class])){
            $reflection = new \ReflectionClass(static::class);
            static::$cache[$class] = $reflection->getConstants();
        }

        return static::$cache[$class];
    }
}

$yes = new BoolEnum("是");
echo $yes; // "是"

abstract Enum
{
    protected $value;

    public function __construct($value)
    {   
        if ($value instanceof static) {
            $value = $value->getValue();
        }

        if(! $this->isValid($value)){
            throw new \UnexpectedValueException("$value 不属于该枚举值" . static::class);
        }

        $this->value = $value;
    }

    // 获取实例对应的键
    public function getKey(){
        return array_search($this->value, static::toArray(), true);
    }

    // 获取实例对应的值
    public function getValue()
    {
        return $this->value;
    }

    // 允许字符串形式输出
    public function __toString()
    {
        return $this->value;
    }

    // 验证值是否合法
    public function isValid($value)
    {
      $arr = static::toArray();

      return in_array($value, $arr, true);
    }

    // 验证键是否合法
    public function isValidKey($key)
    {
      $arr = static::toArray();

      return array_key_exists($key, $arr);
    }
}

$user->banned = ‘非法值‘;  // 可能不会报错
$yes = new BoolEnum("非法值"); // 将会抛出异常
$user->banned = $yes;

function setUserStatus(BoolEnum $boolEnum){
    $user->banned = $boolEnum;
}