[Boost-bugs] [Boost C++ Libraries] #12921: Linker Error with numpy in boost/python

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:

 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

 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"
 #include <boost/python.hpp>

 char const* greet()
     return "hello, world";

     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

 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()
     p::object tu = p::make_tuple('a', 'b', 'c');
     np::ndarray const example_tuple = np::array(tu);
 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
 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 &)"
 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>
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