[C++-sig] (David Abrahams)numpy.ndarray did not match PyArrayObject *

[David Abrahams]

Philip Austin <paustin at eos.ubc.ca> writes:

> so instead of getting PyArray_Type directly, as in the noddy
> example in boost_1_33_1/libs/python/test/m1.cpp, it's provided by 
> the line:
>
> #define PyArray_Type (*(PyTypeObject *)PyArray_API[2])
> which you get when you include __multiarray_api.h
>
> I think this indirection is causing problems for 
> lvalue_from_pytype<extract_array_object, &PyArray_Type>();
> since I can't get this to work either.

Yeah, that would be a problem.  lvalue_from_pytype needs a
compile-time constant for the Python type.  

Something like this will work, though:

   //
   // untested
   //

   void* extract_pyarray(PyObject* x)
   {
       return PyObject_TypeCheck(x, &PyArray_Type) ? x : 0;
   }

   BOOST_PYTHON_MODULE( /*your module name here*/ )
   {
       boost::python::converter::registry::insert(
             &extract_pyarray, type_id<PyArrayObject>());
   }

HTH,

-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com