[Development] Work on qDebug and friends - debug areas

[kai.koehne at nokia.com]

Hi,

One of the things still missing in the current debugging framework is to categorize messages by area: This would allow you to enable/disable e.g. debug messages for only one part of your app ... 

KDE & kDebug

Here debug categories are basically ints, which have to be registered 'kdelibs/kdecore/kdebug.areas'. You can pass your specific as an argument to kDebug(..) et al., but usually you just set a define (KDE_DEFAULT_DEBUG_AREA).

+ comparing int's is fast
- one central registry needed for debug areas (no go for custom apps?)

Log4cxx ...

Frameworks like log4cxx (http://www.360doc.com/content/09/0508/23/36491_3425784.shtml) that are modeled after log4j use free text to define areas. Also, the areas might be nested, so that "MyModule " includes "MyModule.Part" semantically, and you can do very fine grain adjustments on what exactly to log.

+ Lots of flexibility
- comparing strings is slow, chances that you mistype ...


That's at least what I got after doing 10 minutes of research :) Question is whether we want to have any of the approaches (or both) in QtCore? 

Regards

Kai