Subject: [Boost-bugs] [Boost C++ Libraries] #12921: Linker Error with numpy in boost/python
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2017-03-22 12:49:15
#12921: Linker Error with numpy in boost/python
----------------------------+------------------------------
Reporter: niko.koester@⦠| Type: Bugs
Status: new | Milestone: To Be Determined
Component: None | Version: Boost 1.63.0
Severity: Problem | Keywords:
----------------------------+------------------------------
I am the author of the attached (and solved) stackoverflow question:
http://stackoverflow.com/questions/42899376/lnk2001-error-when-using-
boostnumpy/42936160#42936160
My question is, is the described behavior a bug?
Let me start with the answer:
Import the Boost\python numpy package like:
#define BOOST_LIB_NAME "boost_numpy"
#include <boost/python.hpp>
The Problem description (copy from Stackoverflow):
I am trying to call a C++ .dll from Python and return a numpy array. I am
using
Anaconda 2.7 x64
Visual Studio 2013 update 5
boost 1.63.0 prebuileded for lib64-msvc-12.0
I managed to compile this simple example frome here and run it in Python:
#include "stdafx.h"
#define BOOST_PYTHON_STATIC_LIB
#include <boost/python.hpp>
char const* greet()
{
return "hello, world";
}
BOOST_PYTHON_MODULE(test)
{
using namespace boost::python;
def("greet", greet);
}
I am unsure about the #define BOOST_PYTHON_STATIC_LIB but without it
python could not open the pyd file. I suspected that python could not
resolve the references to MSVCR120.dll in the dynamic build, but I am just
guessing.
Next step was to include <boost/python/numpy.hpp> and follow this
instuctions and start with just creating a numpy::ndarray. Yes, I am aware
that void is in contradiction to the intention of getting values, I just
wanted to keep things as simple as possible.
#include <boost/python/numpy.hpp>
namespace p = boost::python;
namespace np = boost::python::numpy;
void getNPArray()
{
Py_Initialize();
np::initialize();
p::object tu = p::make_tuple('a', 'b', 'c');
np::ndarray const example_tuple = np::array(tu);
return;
}
The import and namespace declarations compile without error. At next step
I encountered the linker error. While Py_Initialize() worked fine, the
np::initialize() causes the linker to throw
error LNK2001: unresolved external symbol "void __cdecl
boost::python::numpy::initialize(bool)"
(?initialize_at_numpy@python_at_boost@@YAX_N_at_Z)
And np::ndarray const example_tuple = np::array(tu) causes a
error LNK2001: unresolved external symbol "class
boost::python::numpy::ndarray __cdecl boost::python::numpy::array(class
boost::python::api::object const &)"
(?array_at_numpy@python_at_boost@@YA?AVndarray_at_123@AEBVobject_at_api@23@@Z)
As the linker is perfectly happy with the first example I am toally
confused about what is going on here. I also tried to comment out all
parts from the first example and just compile the second part witout any
change in behaviour.
-- Ticket URL: <https://svn.boost.org/trac/boost/ticket/12921> Boost C++ Libraries <http://www.boost.org/> Boost provides free peer-reviewed portable C++ source libraries.
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