[PyKDE] QColorGroup

[Phil Thompson]

Pete Ware wrote:
> 
> With 0.9, it appears that ColorGroup.foreground() (et. al.) are
> returning the result as a QColorGroup object instead of a QColor
> object.  Following is some sample code and the error
> 
>         self.app = qt.QApplication (sys.argv)
>         pallete = qt.QPalette (qt.blue)
>         n = normal_group = pallete.normal ()
> 
>         print n, n.foreground, n.foreground ()
> 
>         my_group = qt.QColorGroup (n.foreground (),
>                                    n.background (),
>                                    n.light (),
>                                    n.dark (),
>                                    n.mid (),
>                                    n.text (),
>                                    n.background ())
> 
> This is from the "print".  Notice the last one is a QColorGroup
> instead of QColor.
> 
> <qt.QColorGroup instance at faee0>
> <built-in method foreground of QColorGroup object at 261a98>
> <qt.QColorGroup instance at faee0>
> 
> Looking at the code in sipQColorGroup.cpp:
> 
>         res = &((QColorGroup *)sipMapThisToCpp(sipThis,sipClass_QColorGroup)) -> QColorGroup::foreground();
>         return sipMapCppToSelf(res,sipClass_QColor);
> 
> although I don't know anything about sip to be able to comment.  Is
> this a bug or my misunderstanding?
> 
> Thanks,
> --pete

It's definately a bug.  What's happening is that "res" has the same
value that was returned by the call to QPalette::normal() (which was a
QColorGroup).  sipMapThisToCpp() sees this and returns the same
corresponding Python object rather than creating a new one (with a class
of QColor).  So it's not that n.foreground() is returning an object of
the wrong class, it's that it is always returning n.

The root cause of this is that I am a C programmer, not a C++
programmer, and I obviously don't understand how C++ implements
references.  The following is the C++ equivalent of the above code.

#include <stdio.h>
 
#include <qapplication.h>
#include <qpalette.h>
 
int main(int argc,char **argv)
{
	QApplication *app = new QApplication(argc,argv);
	QPalette *palette = new QPalette(blue);
	const QColorGroup *n = &palette -> normal();
 
	printf("n is %0lx\n",(long)n);
	printf("n -> foreground() is %0lx\n",(long)&n -> foreground());
}

Can anybody tell me why the two values displayed are the same?

Thanks,
Phil