Disclaimer: I love C++11! It’s the best thing that happened to C++ since I’m using it (mid-90’s). I’ve been hoping for lambda‘s in C++ since I discovered and started using Lisp. Elisions and move semantics – together with unique and shared pointers – pretty much free you from thinking about memory management! It’s just amazing! Check out “Going Native” talks on YouTube, incl. amazing talks by the likes of Stroustrup, Sutter, Lavavej, et al.
If you don’t want to read my rant, here’s the point – function objects are objects – they can get copied, unless you specify otherwise, so beware that you’re working on a copy, or pass std::ref.
The proper way would not be to check the objectName, which can change at any time, but rather to check if the widget is an instance of QMainWindow. Take advantage of what Qt makes available by using a foreach.
Provided how much you can do with Qt Widgets, or Qt in general, it’s no surprise that such “specialized” function is not present (the QApplication::activeWindow() does not make it, as the window might not be active).
QWidgetList widgets = qApp->topLevelWidgets();
for (QWidgetList::iterator i = widgets.begin(); i != widgets.end(); ++i)
if ((*i)->objectName() == "MainWindow")
return (QMainWindow*) (*i);
If, for whatever reason, you changed the “objectName” property of the main window, update the above if with this name.
This post is more of a mocking than serious advice, provided that a) STL includes <fstream> header with std::ifstream and std::ofstream classes, that do the same without any additional effort, and b) mixing templates and libC is just plain weird in my book. Continue reading →
This has been haunting me for quite some time. When building Qt app for Windows, the QImage::save() function did not work for JPEG for deployed applications, while it did work if Qt SDK was installed on the machine. Continue reading →
Here are few optimization techniques that were handy to me recently; they mostly concern 2D graphics programming, where these patterns often emerge, but are helpful anywhere where you have to iterate and update data.
Yes, it’s a clumsy solution, but it does the work just fine… 😀 Sure, you can catch the lines in array, and afterwards print them one by one back to file, etc. … but it’s just not at all pretty bash script (enhancements and suggestions welcome!).
Notice that the command is pretty much dependent on the format of the line the BuildNum is defined on, and that “BuildNum” should not appear anywhere else as a second word on the line!