swig problem

[Torsten Marek]

Uwe Mayer schrieb:
> Hi,
> 
> I was trying to extend a Qt class in C++ and using this in my Python
> application. I got problems importing the python module:
> 
> I was extending QListViewItem to QListViewItemNumeric. Then I used the
> following to generate the python extension:
> 
> $ gcc -c -I/usr/include/qt3 -I/usr/include/python2.3
> QListViewItemNumeric.cpp
> 
> Then I used swig with an interface file:
> -- snip --
> %module QListViewItemNumeric
> %{
> #include <qlistview.h>
> #include "QListViewItemNumeric.h"
> %}
> class QListViewItemNumeric : public QListViewItem {
> public:
>   QListViewItemNumeric( QListView * parent );
>   virtual void setNumeric( int columns = 0 );
> };
> -- pins --
> 
> And compiled the result:
> 
> $ swig -c++ -python QListViewItemNumeric.i \
> QListViewItemNumeric.i:6: Warning(401): Nothing known about class
> 'QListViewItem'. Ignored.
> 
> $ gcc -c -I/usr/include/qt3 -I/usr/include/python2.3 \
> QListViewItemNumeric_wrap.cxx 
> 
> And linked both together with qt:
> 
> $ gcc -shared QListViewItemNumeric.o QListViewItemNumeric_wrap.o -lqt -o \
> _QListViewItemNumeric.so
> 
> 
> When I omitted the "-lqt" python import told me:
> ImportError: ./_QListViewItemNumeric.so: undefined symbol:
> _ZN13QListViewItemC2EP9QListView
> 
> which I figured out from the manual means I have to link it against the Qt
> library. I am not sure wether "-lqt" is the right thing to do.
> 
> However, using the "-lqt" switch I now get a:
> 
> 
>>>>import QListViewItemNumeric
> 
> Traceback (most recent call last):
>   File "<stdin>", line 1, in ?
>   File "QListViewItemNumeric.py", line 5, in ?
>     import _QListViewItemNumeric
> ImportError: ./_QListViewItemNumeric.so: undefined symbol:
> _ZTV20QListViewItemNumeric
> 
> 
> Can anyone help me over these first steps of using swig?

Unless you insist on using swig (in that case, I can't help you), you 
might want to try out sip (www.riverbankcomputing.co.uk/sip) to work 
with Qt and Python. To find out how to get your (own) Qt classes to work 
with Python, you can have a look at the interface files of PyQt, there 
are plenty of examples.

greets

Torsten