类常量作为数组键

Question

请看下面的代码:

...
class LanguageResources {
    const SESSION_LANGUAGE_KEY = 'lang';

    public static function getLanguageSettingsFilePath() {

        if (isset($_GET[LanguageResources::SESSION_LANGUAGE_KEY])) {
....

我获取最后一行的PHP错误消息.通过常量值进行数组索引访问有什么问题？

Notice: Use of undefined constant SESSION_LANGUAGE_KEY - assumed 'SESSION_LANGUAGE_KEY' in ...languages.php on line 17

Answer 1

在定义常量的类中,您必须引用它self::SESSION_LANGUAGE_KEY.