[Development] Work on qDebug and friends

[BRM]

> From: David Faure <faure at kde.org>
> On Friday 03 February 2012 10:51:50 kai.koehne at nokia.com wrote:
>>  Finally I came around to actually implement something:
>> 
>>  http://codereview.qt-project.org/#change,15129
>> 
>>  The idea is that you can customize the output by setting the
>>  QT_DEBUG_PATTERN environment variable. Setting it e.g. to
>> 
>>  "[%type%] %file%:%line% %function% %message%" 
>> 
>>  Would generate lines like:
>> 
>>  [debug] ../helloworld/main.cpp:7 main HELLO WORLD
> 
> Excellent idea!!!
> Much better than my 6 env vars in KDE!
> 
> Once this goes in I'll add support for %pid%, %processname% and %timestamp%, 
> 
> and we'll be all set :)
> 
>>  However, I'm not really sure whether that belongs into Qt Core or not.
> 
> I would definitely like it to go there.
> A separate module that apps have to link to and initialize, only helps the 
> case of "a developer working on his own application". It doesn't 
> help the more 
> general case of "an opensource developer/user debugging an existing 
> application, or a whole set of applications in an existing 
> framework/desktop".
> There's no way to patch all apps just to be able to distinguish their output 
> 
> in ~/.xsession-errors.
> 
> I agree with logging to files, sockets, syslog etc. being in a separate addon.
> But I would say that making the basic output useful belongs in Qt Core, so 
> that *all* Qt applications in the world can benefit from it.

+1