A better way to check class constants in setters from ZF2's Zend\Http\Request

Request.php

class Request {

    const METHOD_OPTIONS = 'OPTIONS';
    const METHOD_GET     = 'GET';
    const METHOD_HEAD    = 'HEAD';
    const METHOD_POST    = 'POST';
    const METHOD_PUT     = 'PUT';
    const METHOD_DELETE  = 'DELETE';
    const METHOD_TRACE   = 'TRACE';
    const METHOD_CONNECT = 'CONNECT';
    const METHOD_PATCH   = 'PATCH';

    protected $method = self::METHOD_GET;


    public function setMethod ($method) {
        $method = strtoupper($method);
        if (!defined('static::METHOD_' . $method)) {
            throw new Exception\InvalidArgumentException('Invalid HTTP method passed');
        }
        $this->method = $method;
        return $this;
    }

}