[PyQt] Sip and pure virtual functions

[Guðjón Guðjónsson]

Hi Phil and Shaheed

Thanks Shaheed. I tried with the Abstract keyword but I couldn't make it
work

On Wed, Jan 4, 2017 at 11:40 AM, Phil Thompson <phil at riverbankcomputing.com>
wrote:

> On 4 Jan 2017, at 8:16 am, Guðjón Guðjónsson <
> gudjon.i.gudjonsson at gmail.com> wrote:
> >
> > Hi list
> >
> > I have been writing a python wrapper to the qwt6 library. It is new
> code, doesn't
> > build on PyQwt5.
> >
> > Qwt library:
> > http://qwt.sourceforge.net/
> >
> > My python wrapper:
> > https://github.com/GauiStori/PyQt-Qwt
> >
> > I do have a problem with pure virtual functions in Qwt.
>
> So what is the problem?
>

If I don't use the patch, I get the following error:

g++ -c -g  -g -O2 -fstack-protector-strong -Wformat
-Werror=format-security  -Wdate-time -D_FORTIFY_SOURCE=2 -fPIC -Wall -W
-DNDEBUG -I. -I/usr/include/x86_64-linux-gnu/qt5/
-I/usr/include/x86_64-linux-gnu/qt5/QtCore/
-I/usr/include/x86_64-linux-gnu/qt5/QtGui/
-I/usr/include/x86_64-linux-gnu/qt5/QtWidgets/ -I/usr/include/qwt/
-I/usr/include/python3.5m -o sipQwtQwtSeriesStoreQwtSetSample.o
sipQwtQwtSeriesStoreQwtSetSample.cpp
./sipQwtQwtSeriesStoreQwtSetSample.cpp: In function ‘void*
array_QwtSeriesStoreQwtSetSample(Py_ssize_t)’:
./sipQwtQwtSeriesStoreQwtSetSample.cpp:372:52: error: invalid
new-expression of abstract class type ‘QwtSeriesStore<QwtSetSample>’
     return new QwtSeriesStoreQwtSetSample[sipNrElem];
                                                    ^
In file included from qwt_series_store.sip:68:0:
/usr/include/qwt/qwt_series_store.h:57:7: note:   because the following
virtual functions are pure within ‘QwtSeriesStore<QwtSetSample>’:
 class QwtSeriesStore: public virtual QwtAbstractSeriesStore
       ^~~~~~~~~~~~~~
/usr/include/qwt/qwt_series_store.h:31:18: note:        virtual void
QwtAbstractSeriesStore::dataChanged()
     virtual void dataChanged() = 0;
                  ^~~~~~~~~~~
./sipQwtQwtSeriesStoreQwtSetSample.cpp: In function ‘void*
copy_QwtSeriesStoreQwtSetSample(const void*, Py_ssize_t)’:
./sipQwtQwtSeriesStoreQwtSetSample.cpp:379:114: error: invalid
new-expression of abstract class type ‘QwtSeriesStore<QwtSetSample>’
     return new QwtSeriesStoreQwtSetSample(reinterpret_cast<const
QwtSeriesStoreQwtSetSample *>(sipSrc)[sipSrcIdx]);

^
Makefile:17: recipe for target 'sipQwtQwtSeriesStoreQwtSetSample.o' failed
make: *** [sipQwtQwtSeriesStoreQwtSetSample.o] Error 1

But if I use the patch everything works like charm. I would very much like
not to add this patch to the Qwt library because
I think there must be a way around it in Sip.

The sip files, patch and .h files are attached.


> > Another problem is getting the Qt include dir into the configure.py
> script.
> > I have to admit that I don't understand how it is done in the QScintilla
> script.
> > Can anyone point me to another example?
>
> Again, what is the problem?
>

I cannot find out how to obtain the Qt include directory automatically in
the configure.py script.
For PyQt4 it is simple

from PyQt4 import pyqtconfig
pyqtconfig.Configuration().qt_lib_dir

But I don't know how to do this for PyQt5.

Regards
Gudjon
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