Qt First Impressions

Qt is a cross-platform, C++ library that provides many features, including a GUI toolkit, networking, XML/JSON serialization/deserialization, and more.

I recently gave it a try by writing two small application with it:

• A real-time chat client using websockets and
• a client for freebee.fun, a clone of the NYT’s Spelling Bee game.

What I liked

• Signals and slots:
  Creating and connecting signals/slots is very ergonomic. In my opinion,

  QObject::connect(sender, signal, receiver, slot); // Qt
  

  is a lot more intuitive than

  m_button.signal_clicked().connect(sigc::mem_fun(target, handler)); // gtkmm
  

• QtDesigner (and the wealth of tooling in the Qt ecosystem):
  I like how you can quickly throw together a UI in QtDesigner and have moc automatically translate it into usable code. It also helps creates a nice separation between the program logic and the user interface. I know that GTK’s Glade is similar, but I never seem to be able to get it to work correctly.
• Lots of features:
  There are a ton of modules that cover pretty much everything you need, including networking and database access.
• The docs are really good.
• It’s actually cross-platform (compiles on Windows without shenanigans)

Things I’m not so sure about

• QString, QList, and all the other Qt-specific data structures:
  While they provide more features and are in some ways better than the STL implementations (e.g. with implicit sharing / COW making and parenting to make handling memory easier), it is rather annoying to have to constantly convert back and forth between them when using non-Qt libraries. This dynamic leads to it being more convenient to just use Qt everything instead of dealing with conflicts between the Qt way and the STL way.
• The QObject parent/child relationship:
  It appears that the convention in Qt is to construct QObjects on the free store using new and with a raw pointer to a parent object, which would then handle deallocation for you. While this dynamic is rather convenient, I’m not quite so sure if I like this approach to memory management over, say, RAII.

Final thoughts

Overall, I enjoyed working with Qt; it was, if anything, quite ergonomic. Even with no prior experience, I was able to get up and running pretty quickly and only spent a few hours on each app. So, if I ever find myself in a position where I need to write a GUI app in C++, I’d definitely consider working with Qt again.