[PyKDE] Using SIP modules from embedded Python

[Paul Giannaros]

On Monday 19 February 2007 15:34, Phil Thompson wrote:
> On Monday 19 February 2007 3:15 pm, Paul Giannaros wrote:
> > On Monday 19 February 2007 13:34, Phil Thompson wrote:
> > > On Monday 19 February 2007 12:55 pm, Paul Giannaros wrote:
> > > > Hi there,
> > > > I have wrapped key bits of Kate's interface (as documented at
> > > > http://developer.kde.org/documentation/library/3.5-api/kdebase-apidoc
> > > >s/ ka te /html/) with SIP. Firstly, thanks for SIP -- along with good
> > > > documentation, ease of use, and Qt/KDE support it was a piece of
> > > > cake. However, my intention is to use that library from within a C++
> > > > Kate Plugin. The plugin embeds Python and (so far) just attempts to
> > > > import the SIP-created module. Doing so gives an ImportError,
> > > > however, which I do not get if I just import the module from the
> > > > interactive
> > > > interpreter.
> > > >
> > > > The error is:
> > > > ImportError: /usr/lib/python2.5/site-packages/sip.so: undefined
> > > > symbol: _Py_ZeroStruct.
> > > >
> > > > Both my C++ plugin and my SIP extension link to python (the SIP
> > > > extension does because if I don't I get a 'PyCObject_Type' undefined
> > > > error when trying to import it).
> > > >
> > > > Another interesting thing is that If I isolate the importing code
> > > > from the Kate plugin with a simple application, it imports fine.
> > > >
> > > > Any ideas what's going wrong?
> > >
> > > There are a couple of things your plugin needs to do (for a Qt4 example
> > > see the new Designer plugin in current PyQt4 snaphots).
> > >
> > > You need to make sure the Python shared library is loaded and that it
> > > exports all of its symbols.
> >
> > I'm currently just linking to it on the command line (via -lpython2.5)
> > when I link my library. I see from designer/pluginloader.cpp that you use
> > QLibrary::load as well? I tried doing that but setLoadHints isn't
> > available here (Qt 3.3) and just calling load() causes the same error.
>
> There is a way to do it - but I can't remember what it is at the moment.
> Have a look through the PyKDE source code - it will be in there somewhere -
> related to loading KParts.
>

Couldn't find how to do it in PyKDE (tried all manner of searches for 
QLibrary/KLibrary) so I resorted to looking at Qt 4.3's load() call. It just 
passes an extra flag to dlopen, so I got rid of QLibrary and did the dlopen 
call myself. Not exactly cross-platform, but it seems to work :-). Thanks

> > > You should also make sure you link against the Python shared library
> > > and not the static one.
> >
> > I can verify that I'm linking to the shared library via `ldd
> > mykateplugin.so`: ....
> > libpython2.5.so.1.0 => /usr/lib/libpython2.5.so.1.0 (0xb7d16000
> > ....
>
> Phil
>
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