Re: [LAD] GTK+ vs QT for new Open Source Project.

On Friday, August 14, 2009, Paul Davis wrote: Of course you need a pre-processor to use libsigc++. The pre-processor is a standard part of the C++ (or plain C) compilation chain, for instance the "cpp" program for the GCC compiler. It takes care of expanding macros, compile directives and conditional compilation. Maybe you are thinking about the Qt's "moc" code generator tool. It reads a C++ header file, and if it finds one or more class declarations that contain the Q_OBJECT macro, it produces a C++ source file containing the meta-object code for those classes. This code implements the calls and callbacks for Qt's native signals and slots, among other things. MOC is not a pre-processor because it doesn't replace any text in the original header file before the next compilation step. It is only a code generator. The original header is a standard C++ header that can be used as-is by a C++ compiler. The main (functional) difference between the two systems is that Qt's signals and slots can be manipulated at runtime, while you can't do the same with libsigc++, that freezes the connections at compile time. Manipulate means that you can connect and disconnect signals and slots at runtime, store and retrieve those connections from a text or XML file, and so on. This also makes Qt's signal/slots a little more expensive in processing time over libsigc++. Here is a comparision between them: http://libsigc.sourceforge.net/benchmark.shtml Why Doesn't Qt Use Templates for Signals and Slots? http://doc.trolltech.com/templates.html Qt's native signal/slot mechanism isn't mandatory to developt Qt-based applications. It is possible to use Boost, libsigc++ or something else. See: http://doc.trolltech.com/signalsandslots.html#using-qt-with-3rd-party-signa… Regards, Pedro