Comment Qt does not support all of C++ (Score 5, Informative) 517
I have been using Qt for the last 1.5 years to develop an application for post-processing of segmented (medical) image data as part of my master thesis. The application is available under the GPL at sourceforge
During development one major disadvantage of Qt has surfaced, and I think it shows that the Trolltech has choosen a terribly wrong solution to a complex problem.
In order to support their signals-and-slots mechanism (which is an elegant concept, and allows for easy implementation of both the model-observer pattern and the mediator pattern) they have added two new keywords to the language, namely signals and slots. In order to support these you _HAVE_ to run a preprocessor called moc (Meta Object Compiler) for your program to link. But moc does not support templates.
Mostly we have managed to work around this limitation by having a non-template superclass which declares the signals and slots (luckily slots can be virtual) and then have the template parts in a subclass, but this leads to unnatural class hierarchies.
Other libraries have managed to support a signals-and-slots mechanism without such an ugly hack. Both Boost.signals and libsic++ implement them. However their syntax is not as nice as Qt's. If C++ really need even more syntax is of course another question :-)
While not all applications rely upon templates, they have some interesting uses, and if an applications first starts to use them, most classes easily ends up as template classes. See the book Modern C++ Design for "new-school" uses of templates. This could easily be the direction C++ development is headed, and it's a shame Qt will not be able to be a part of it.
During development one major disadvantage of Qt has surfaced, and I think it shows that the Trolltech has choosen a terribly wrong solution to a complex problem.
In order to support their signals-and-slots mechanism (which is an elegant concept, and allows for easy implementation of both the model-observer pattern and the mediator pattern) they have added two new keywords to the language, namely signals and slots. In order to support these you _HAVE_ to run a preprocessor called moc (Meta Object Compiler) for your program to link. But moc does not support templates.
Mostly we have managed to work around this limitation by having a non-template superclass which declares the signals and slots (luckily slots can be virtual) and then have the template parts in a subclass, but this leads to unnatural class hierarchies.
Other libraries have managed to support a signals-and-slots mechanism without such an ugly hack. Both Boost.signals and libsic++ implement them. However their syntax is not as nice as Qt's. If C++ really need even more syntax is of course another question
While not all applications rely upon templates, they have some interesting uses, and if an applications first starts to use them, most classes easily ends up as template classes. See the book Modern C++ Design for "new-school" uses of templates. This could easily be the direction C++ development is headed, and it's a shame Qt will not be able to be a part of it.
