I’ve been writing programs with Qt since the Qt 3 era, and when I made my first Qt 4 programs available for general use I added cross platform support. One thing that entails is storing user data files in different locations on different platforms. At the time, I couldn’t find any way in Qt to do that, so I ended up writing this in CuteMaze:
QString homeDataPath()
{
#if defined(Q_OS_MAC)
QString path = QDir::homePath() +
"/Library/Application Support/GottCode/CuteMaze";
#elif defined(Q_OS_UNIX)
QString path = qgetenv("XDG_DATA_HOME");
if (path.isEmpty()) {
path = QDir::homePath() + "/.local/share";
}
path += "/games/cutemaze";
#elif defined(Q_OS_WIN32)
QString path = QDir::homePath() +
"/Application Data/GottCode/CuteMaze";
#endif
return path;
}
I’ve never been happy with that code. For one thing, it uses platform specific code in a platform independent codebase, which limits the number of supported platforms to those I can easily test myself. Thankfully, I will notice any bugs I introduce in one platform but not the rest, since I build my programs on those platforms.
However, I was recently made aware of the fact that CuteMaze would not compile on less common platforms, and that piece of code was one of the reasons. I figured that this was a chance to improve said code, so I went looking to see if there is a better way to write… and there is! After I released CuteMaze, a new class for desktop integration was added to Qt. The above code would be better written like this:
QString homeDataPath()
{
return QDesktopServices::storageLocation( QDesktopServices::DataLocation ) + "/CuteMaze";
}
The above functionality was added in Qt 4.4. Instead of using it, I have been dragging the messy and inferior code from project to project. Obviously I don’t re-solve every problem I come to, I remember what I have done or what I have read about. It’s only natural I will miss things when reading about new versions of Qt.
Now that I know about this, I am going to use the new code for the platforms not already supported. In future projects I will use only the new code, but I don’t want to go through the headache of moving all of the user data files for all of my current projects.