What advantages does C++ have over other languages for Qt development?

As well-known, C++ has steeper learning curve than most of the mainstream languages, which results in better performance . But, does using C++ over other languages[like Java,Ruby,Python] for Qt development have still (major) advantages,let's say about Qtopia? If any, what are they?

From stackoverflow Comptrol

• it's easier to create a single executable.

  don't know if that will be for long...

  From Javier

• Qt is natively a C++ API, so any other languages have to have wrapper code around it which needs to be maintained, etc. The primary documentation will also be for the C++ API.

  I'm not sure if there are any "official" bindings to other languages which are maintained and released together with Qt.

  Barry Wark : Qt Jambi is an official Java binding for Qt
  From JesperE

• If you are looking at Qtopia, you are probably looking into embedded systems. In that case, C++ will likely be the one you want to choose, specifically for those performance reasons.

  Otherwise, Trolltech maintains a Java binding, and I imagine that some of the other language bindings aren't too bad either, since those languages can interact directly with c/c++ code. However, those bindings are likely to always be a little out of date.

  From Caleb Huitt - cjhuitt

• and Here is my answer to my own question:

  http://trolltech.com/products/appdev/programming-language-support

  From Comptrol