Debugging

[Boudewijn Rempt]

On Thu, 6 Apr 2006, Leonardo Giordani wrote:

> Hi all,
> 
> I spent last 2 weeks chasing a bug in my watercolors and finally today I 
> solved it. I'm not sure how, but this is matter for another discussion ;-)
> 
> I want to ask advices about debugging: how do you debug it? I was using the 
> most primitive form of debugging, inserting printf() to show values, but I'm 
> sure there is something better.

valgrind is meant as a tool to check memory leaks and boundary errors, but
in my experience, most of my bugs are exactly boundary errors, so running
with valgrind is often enough to pinpoint the bug. It helps to de-install
as many plugins as possible to make valgrind startup a bit faster.

> Can Krita be run under gdb/ddd? How can I activate the "-g" option and 
> deactivate "-O"?

In my experience, -O doesn't make ddd get confused with Krita. What I do is
configure with

CXXFLAGS=-g ./configure --enable-debug=full

Then I start ddd with

ddd /path/to/installed/krita

You cannot run without installing.

> 
> What are the debugging facilities of KDE/Qt?

#include <kdebug.h>
kdDebug() << "bla " << value << endl;
kdWarning()
kdError()

> 
> I currently do not use KDevelop, mostly because I always forget to download 
> the packages to install it (I have no Internet acces at home): does it have a 
> connection with gdb?

It has, but I've never used it.

> 
> Today my brush painted watercolors for the first time. It was exciting. Colors 
> were wrong, horrible and with some strange pixel here and there, but after 2 
> weeks of "nan" values it is a big victory. :-)

Congratulations!