[C++-sig] Can boost.python and PyQt be used together?

[Paul F. Kunz]

>>>>> On Sat, 07 Dec 2002 15:02:53 -0500, David Abrahams <dave at boost-consulting.com> said:

> "Paul F. Kunz" <Paul_Kunz at SLAC.Stanford.EDU> writes:
>> I have some widgets which inherit from Qt and made them as Python
>> extension module using boost.python (v2).

> So, in Python they're represented as Boost.Python extension
> instances containing instances of your widget classes (?)

  Yes.  My C++ objects are wrap by Boost.Python

>> Now another group wants to use them in their application built with
>> PyQt which uses SIP to make the Python extension modules.  At first
>> glance, it looks like this wouldn't work.

> If I understand you correctly, whether it would work or not depends
> on how sophisticated SIP can be about unwrapping a Boost.Python
> extension instance and retrieving the underlying C++ object. I doubt
> SIP has this ability built-in, but it may be possible for you to add
> it.

   I don't see why SIP needs to know my objects are wrapped by
Boost.Python.   But let me show you some Python code

a = QApplication(sys.argv) 
clock = DigitalClock()
clock.resize(170,80)
a.setMainWidget(clock)
clock.show()
# the above are Python objects wrapped with SIP
# below are my objects wrapped with Boost.Pythoin
wc = WindowController()
cw = wc.newCanvas()

a.exec_loop()


> 1. Get Boost.Python to wrap your objects in a way that SIP already
> undertstands

> 2. Get SIP to understand the way Boost.Python already wraps objects

   Why should SIP need to know about my objects or vica versa?

I've trace the point of a problem a bit further.   Steping down the
call stack, I see...

#6  0x0807705e in eval_frame (f=0x811a974) at Python/ceval.c:1784
(gdb) 
#5  0x08056794 in PyObject_GetAttr (v=0x82cc4cc, name=0x815a8e0)
    at Objects/object.c:1108
(gdb) 
#4  0x401afa43 in instanceGetAttr ()
   from /usr/local/lib/python2.2/site-packages/libsip.so

Note the function is in libsip.so.   The line in PyObject_GetAttr()
that got us there appears to be...

	if (tp->tp_getattro != NULL)
		return (*tp->tp_getattro)(v, name);

Perhaps SIP depends on overriding something in Python in order to
interact with it's extension modules.