Re: [Boost-users] [boost.python] use of multi_array in python

From: Sebastien Fortier (sebastien.fortier_at_[hidden])
Date: 2006-07-04 06:29:30

Thank you again for the quick reply! I will try what you have suggested.
One last question, If I have a header file to export with its 
implementation file, how do I go about linking the object file with the 
library that is created with bjam? When I start bjam to compile the 
shared library it does not link nor compile the implementation file with 
the shares library...

Ex.:

// Boost Includes 
==============================================================
#include "boost/multi_array.hpp"
#include "boost/python.hpp"
#include "boost/cstdint.hpp"

// Includes 
====================================================================
#include "Fstd.h"
#include "MatrixAlgorithm2D.h"

// Using 
=======================================================================
using namespace boost::python;

// Module 
======================================================================
BOOST_PYTHON_MODULE(matrix)
{
    class_< Fstd >("Fstd", init< const Fstd& >())
        .def(init< std::string >())
        .def("getTT", &Fstd::getTT)
        .def("getUV", &Fstd::getUV)
    ;

    class_< MatrixAlgorithm2D >("MatrixAlgorithm2D", init<  >())
        .def(init< const MatrixAlgorithm2D& >())
        .def("windChill", &MatrixAlgorithm2D::windChill)
        .def("display_d", &MatrixAlgorithm2D::display_d)
        .staticmethod("windChill")
        .staticmethod("display_d")
    ;

    class_<boost::multi_array<double, 2> >("multi_array_2d");
    class_<boost::const_multi_array_ref<double, 2> 
 >("const_multi_array_ref_2d");

    implicitly_convertible<multi_array<double, 2>, const_multi_array_ref<double, 2> >();

}

I have MatrixAlgorithm2D.h, Fstd.h and Fstd.cpp, when I execure bjam the 
shared library is created but not the object file for Fstd.cpp, so when 
I try to use this from Python, it fails...

Daniel Wallin wrote:

>Sebastien Fortier wrote:
>  
>
>>Thank you very much Daniel!
>>
>>I had another question, is it possible to use multi_array and 
>>const_multi_array_ref together in python.
>>What I mean is, if I create a multi_array from python through my c++ 
>>functions and I want to pass this array to another c++ function that 
>>uses a const_multi_array_ref how do I manage this in the interface file? 
>>is this possible?
>>
>>I added class_<const_multi_array_ref<double, 2> 
>> >("const_multi_array_2d_ref"); to my interface file but the types seem 
>>to be incompatible.
>>    
>>
>
>You need to let Boost.Python know that the types are convertible:
>
>  implicitly_convertible<
>      multi_array<double, 2>
>    , multi_array_ref<double, 2>
>  >();
>
>  implicitly_convertible<
>      multi_array<double, 2>
>    , const_multi_array_ref<double, 2>
>  >();
>
>Should do it. See http://www.boost.org/libs/python/doc/v2/implicit.html.
>
>  
>
>>I would prefer to use the const_multi_array_ref with the multi_arrays to 
>>avoid copies...
>>    
>>
>
>If you already have multi_array's, why don't you just pass them by
>reference?
>
>  
>

-- 
Sébastien Fortier