[C++-sig] need 16 arguments to a function...

[anders langlands]

Hmmm OK now I actually try and use it, it crashes. This is very strange. I'm
using almost exactly the same code in another part of my module for getting
values back from a list.

The code looks like this:

M44f m44f_new( list ls )
    {
        size_t len =  boost::python::extract<size_t>( ls.attr( "__len__" )()
);
        M44f m;
        cerr << "Length is " << len << endl;
        for ( int i=0; i < len; ++i )
        {
            cerr << "getting item " << i << endl;
            boost::python::object x = ls[i];
            boost::python::extract<float> ex( x );
            if ( ex.check() )
            {
                *(m[ i ]) = ex();
            }
        }

        return m;
    }

and the output and gdb backtrace looks like this:

Length is 16
getting item 0
getting item 1
getting item 2
getting item 3
getting item 4
getting item 5

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread -1210632528 (LWP 5042)]
0xb7cb33a5 in boost::python::incref<_object> (p=0x0)
    at /usr/include/boost/python/refcount.hpp:16
16          Py_INCREF(python::upcast<PyObject>(p));
Current language:  auto; currently c++
(gdb) bt
#0  0xb7cb33a5 in boost::python::incref<_object> (p=0x0)
    at /usr/include/boost/python/refcount.hpp:16
#1  0xb7ab1762 in object_base (this=0xbf82dfa8, rhs=@0xbf82e03c)
    at /usr/include/boost/python/object_core.hpp:419
#2  0xb7ab1794 in object (this=0xbf82dfa8)
    at /usr/include/boost/python/object_core.hpp:294
#3  0xb7ab7e73 in proxy (this=0xbf82dfa8, target=@0xbf82e03c,
key=@0xbf82df08)
    at /usr/include/boost/python/proxy.hpp:58
#4  0xb7ab7ec2 in
boost::python::api::object_operators<boost::python::api::object>::operator[]
(this=0xbf82e03c, key=@0xbf82df08)
    at /usr/include/boost/python/object_items.hpp:36
#5  0xb7ab93d1 in
boost::python::api::object_operators<boost::python::api::object>::operator[]<int>
(this=0xbf82e03c, key=@0xbf82dfb4)
    at /usr/include/boost/python/object_items.hpp:61
#6  0xb7ac872a in PymathBinding::m44f_new (ls=@0xbf82e03c) at
src/Pymath.cpp:89
#7  0xb7ae460c in
boost::python::detail::invoke<boost::python::to_python_value<Imath::Matrix44<float>
const&>, Imath::Matrix44<float> (*)(boost::python::list),
boost::python::arg_from_python<boost::python::list> > (rc=@0xbf82e07e,
    f=@0x817f794, ac0=@0xbf82e070)
    at /usr/include/boost/python/detail/invoke.hpp:75
#8  0xb7ae49bf in
boost::python::detail::caller_arity<1u>::impl<Imath::Matrix44<float>
(*)(boost::python::list), boost::python::default_call_policies,
boost::mpl::vector2<Imath::Matrix44<float>, boost::python::list>
>::operator() (
---Type <return> to continue, or q <return> to quit---
    this=0x817f794, args_=0xb7d0180c)
    at /usr/include/boost/python/detail/caller.hpp:199
#9  0xb7ae4a1a in
boost::python::objects::caller_py_function_impl<boost::python::detail::caller<Imath::Matrix44<float>
(*)(boost::python::list), boost::python::default_call_policies,
boost::mpl::vector2<Imath::Matrix44<float>, boost::python::list> >
>::operator() (this=0x817f790, args=0xb7d0180c, kw=0x0)
    at /usr/include/boost/python/object/py_function.hpp:38
#10 0xb7bbc6d6 in boost::python::objects::function::call ()
   from /usr/lib/libboost_python-gcc-mt-1_33_1.so.1.33.1
#11 0x0817f790 in ?? ()
#12 0xb7d0180c in ?? ()
#13 0x00000000 in ?? ()


I'm calling it like this in the python script:

xform = newM44f( [ 1.000000, 0.000000, 0.000000, 0.000000, 0.000000,
1.000000, 0.000000, 0.000000, 0.000000, 0.000000, 1.000000, 0.000000,
0.000000, 0.000000, 7.367355, 1.000000, ] )



Any ideas what could be happening?

A

On 11/25/06, anders langlands <anderslanglands at gmail.com> wrote:
>
> Aha yes that's much better, thank you
>
> A
>
> On 11/25/06, Stefan Seefeld <seefeld at sympatico.ca> wrote:
> >
> > anders langlands wrote:
> > > Can I change the max arguments limit for methods without recompiling
> > > boost::python? I need an initializer for a 4x4 matrix, hence the need
> > > for 16 floats.
> >
> > FWIW, I have used hand-coded construction / conversion code to generate
> > C++ containers ('Vector', here) from python lists, such as this:
> >
> > std::auto_ptr<Vector> construct_vector(bpl::list l)
> > {
> >   long len = bpl::extract<long>(l.attr("__len__")());
> >   std::auto_ptr<Vector> vector(new Vector(len));
> >   for (long i = 0; i != len; ++i) vector->put(i,
> > bpl::extract<double>(l[i]));
> >   return vector;
> > }
> >
> > May be something similar would work for you, too ?
> >
> > HTH,
> >                 Stefan
> >
> >
> > --
> >
> >       ...ich hab' noch einen Koffer in Berlin...
> > _______________________________________________
> > C++-sig mailing list
> > C++-sig at python.org
> > http://mail.python.org/mailman/listinfo/c++-sig
> >
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.python.org/pipermail/cplusplus-sig/attachments/20061125/e77f8661/attachment.htm>