[C++-sig] Function taking Virtual Base Pointer

[Thomas Muldowney]

If I take out the no_init I can no longer compile because of the
abstract member function.  Perhaps I need to be using a CVS copy of
boost?  Here is the complete error:

/opt/boost-gcc-3.2/include/boost/python/class.hpp: In constructor 
   `boost::python::detail::assert_default_constructible<T>::assert_default_constructible()
   [with T = A]':
/opt/boost-gcc-3.2/include/boost/python/class.hpp:433: instantiated from `boost::python::class_<T, X1, X2, X3>::class_(const char*, const char*) [with T = A, X1 = boost::noncopyable, X2 = boost::shared_ptr<A_cb>, X3 = boost::python::detail::not_specified]'
testMOD.cpp:25:   instantiated from here
/opt/boost-gcc-3.2/include/boost/python/class.hpp:101: cannot allocate an 
   object of type `A'
/opt/boost-gcc-3.2/include/boost/python/class.hpp:101: because the following 
   virtual functions are abstract:
testMOD.cpp:7:  virtual void A::onCommand()


--temas


On Thu, Dec 12, 2002 at 06:10:18PM -0500, David Abrahams wrote:
> Thomas Muldowney <temas at box5.net> writes:
> 
> > I'm trying to implement an event listener class from my C++ library so
> > that python scripts can override it and get the events delivered to them
> > in the script.  After reading the docs it all seemed possible and easy
> > to do.  
> <snip>
> 
> 
> > BOOST_PYTHON_MODULE(testMOD)
> > {
> >     class_<A, boost::noncopyable,
> >     boost::shared_ptr<A_cb> >("A", no_init);
> strike no_init here------------------^^^^^^^
> You don't really need shared_ptr; but it's OK.
> 
> >     def("test_Aptr", test_Aptr);
> > }
> >
> >
> > Python test script:
> > from testMOD import *
> >
> > class MyA(A):
> >     ## Don't get yelled at because we pass off to the non existant internal
> >     ## constructor
> >     def __init__(self):
>           
> You need to call the base class __init__ here to create the C++
> instance.  Or you can do it the easy way; just remove the __init__
> function here.
> 
> >         pass
> 
> >     def onCommand(self):
> >         print "We got a command"
> >
> > a = MyA()
> > test_Aptr(a)
> >
> > Output running it:
> > $ python test_ptr.py 
> > Traceback (most recent call last):
> >   File "test_ptr.py", line 12, in ?
> >       test_Aptr(a)
> > TypeError: bad argument type for built-in operation
> >
> >
> > I really do love everything, this has just been giving me a headache =)
> 
> I love everything too!
> 
> -- 
>                        David Abrahams
>    dave at boost-consulting.com * http://www.boost-consulting.com
> Boost support, enhancements, training, and commercial distribution
> 
> 
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