使用python扩展时链接到其他库（例如boost）

Question

I am calling C++ code from python using the following setup.py - file. (After generating a wrapper using swig).

#!/usr/bin/env python

from distutils.core import setup, Extension

example_module = Extension(
    '_example',
    sources=['example_wrap.cxx', 'example.cpp'],
    swig_opts=['-c++', '-py3'],
    extra_compile_args =['-lboost_math ','-lboost_system ','-Wno-unused-local-typedef'],
    include_dirs = ['/usr/local/include'],
    library_dirs = ['/usr/local/include'],
)

setup (name = 'example',
   version = '0.1',
   ext_modules = [example_module],
   py_modules = ["example"],
)

However, when I try to include other libraries, in this case boost, I get the following error.

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/pathToExample/example.py", line 28, in <module>
_example = swig_import_helper()
  File "/pathToExample/example.py", line 24, in swig_import_helper
_mod = imp.load_module('_example', fp, pathname, description)
  File "/some_path/lib/python3.4/imp.py", line 243, in load_module
    return load_dynamic(name, filename, file)
ImportError: dlopen(/pathToExample/_example.so, 2): Symbol not found: __ZN5boost4math12sph_hankel_1IiiEESt7complexINS0_6detail13bessel_traitsIT_T0_NS0_8policies6policyINS7_14default_policyES9_S9_S9_S9_S9_S9_S9_S9_S9_S9_S9_S9_EEE11result_typeEES5_S6_
  Referenced from: /pathToExample/_example.so
  Expected in: dynamic lookup

Is it maybe a linking problem? How do I have to change setup.py?

Edit1: Added -lboost_system to extra_compile_args

Edit2: Here is my C++ code:

#include <vector>
#include <complex>
#include </usr/local/include/boost/math/special_functions/bessel.hpp>

using namespace std;

vector<float> Test(int n){
    vector<float> a(2);
    complex<double> b = boost::math::sph_hankel_1(0, 1);
    a[1] = real(b);
    return a;    
}

Edit 3: Here the swig code which I use to generate my wrapper

/* File: example.i */
%module example
%include "std_vector.i"

%{
#define SWIG_FILE_WITH_INIT
#include "example.h"
%}

namespace std
{
  %template(FloatVector) vector<float>;
}

std::vector< float > Test(int n);

Edit 4: For completeness also my header file:

/* File: example.h*/

#include <vector>
#include <complex>
#include </usr/local/include/boost/math/special_functions/bessel.hpp>

std::vector<float> Test(int n);

Answer 1

Yes, it's a linking problem as indicated by error:

Symbol not found: __ZN5boost4math12sph_hankel_ ...

You're missing Boost Math.

You need to change your setup.py file by adding -lboost_math to option extra_compile_args .