Thank you both very much.

Well, a class name is not a unique identifier since it's already used to name said class.

Yes, it works. But I found another way of that problem solving. Using of nesting returned Qvalue with qvariant_cast<QList< QPair< QString, QString> > >() also works. Thanks for answer.

Hi, @kshegunov I tried the same thing also your code but I could not manage it to work.. I have already have a Qdatastream, I get quint16 values from it... I tried your solution at first sight... @Wieland The code you send works fine thank you very much.. Have Nice day guys.. Thanks for your help.. It's very valuable..

The two list types are unrelated so casting pointers to them is still not ok at all. To push the previous analogy - for compiler it's like casting int* to string*. You can of course use reinterpret_cast and the compiler will be happy to trust you, but that is in no way correct and will obviously explode in your face at runtime.