qt

I believe many of you who just start reading the source code of Qt will have the question: why Qt uses those private classes? What’s the benefit of such a design pattern? Well, the most significant reason is to keep the binary compatibility.

Though QML provides a nice way to design user interfaces, and JavaScript is employed there to implement the application logic and works pretty nice in many cases, we might still need Qt C++ in some situations (well, at least JavaScript has limited access outside its sandbox).