PHP: Fake Enums with validation

/**
 * PHP: Fake Enums with validation method.
 * @author MrLore <[email protected]>
 */

final class FakeEnums
{
    const ENUM_ONE = 'one';
    const ENUM_TWO = 'two';
    const ENUM_THREE = 'three';

    private static $validConstants;

    private function __construct(){ /* Enum: Instantiation not allowed. */}

    /**
     * Returns true if the specified type is an emum of this class
     *
     * @param mixed $type The value to compare to this class' constants.
     * @return boolean True if $type is a constant of this class.
     */
    public static function isValid($type)
    {
        return in_array($type, (isset(self::$validConstants) ? self::$validConstants : (self::$validConstants = _rv(new ReflectionClass(__CLASS__))->getConstants())));
    }//End isValid()
}//End FakeEnums

/**
 * Allows chaining of methods from their declaration.
 *
 * e.g:
 *
 * new ReflectionClass(__CLASS__)->getConstants();
 *  Produces: syntax error, unexpected '->' (T_OBJECT_OPERATOR)
 *
 * _rv(new ReflectionClass(__CLASS__))->getConstants();
 *  Works fine.
 */
function _rv($val)
{
    return $val;
}//End _rv()