CODEWITHSUNDEEP
c++pythonboost-python
girodt
girodt

Reputation: 379

dependencies between compiled modules in python

Let's say I have two modules in a python project that are written in C++ and exposed with boost::python.

mod1.hpp

#ifndef MOD1_HPP
#define MOD1_HPP

#include <boost/python.hpp>

int square(int x);

#endif

mod1.cpp

#include "mod1.hpp"

using namespace boost::python;

int square(int x)
{
    return x*x;
}

BOOST_PYTHON_MODULE (mod1)
{
    def("square",&square);
}

mod2.hpp

#ifndef MOD2_HPP
#define MOD2_HPP

#include <iostream>
#include <boost/python.hpp>
#include "mod1.hpp"

int myfunc(int x);

#endif

mod2.cpp

#include "mod2.hpp"

using namespace boost::python;

int myfunc(int x)
{
    int y = square(x);
    std::cout << y << std::endl;
}

BOOST_PYTHON_MODULE (mod2)
{
    def("myfunc",&myfunc);
}

As you can see, mod2 is using a function defined in mod1. Compiled without the boost::python wrapper and with a main function, it works perfectly fine.

Now the compile script

setup.py

#!/usr/bin/python2

from setuptools import setup, Extension

mod1 = Extension('mod1',
                 sources = ['mod1.cpp'],
                 libraries = ['boost_python'])

mod2 = Extension('mod2',
                 sources = ['mod2.cpp'],
                 libraries = ['boost_python'])

setup(name='foo',
      version='0.0',
      description='',
      ext_modules=[mod1,mod2],
      install_requires=['distribute'])

it compiles fine. Then I move to build/lib.linux-i686-2.7 and launch python2

>>> import mod1
>>> import mod2
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: ./mod2.so: undefined symbol: _Z6squarei
>>>

Obviously there's a problem with mod2 not finding mod1. How can I fix that ? How can I define several C modules in a python project and allow them to use each others ?

Upvotes: 0

Views: 489

Answers (1)

Janne Karila
Janne Karila

Reputation: 25197

Since mod1 is a Python extension, the clean approach would be to use it just like any other Python module:

object mod1 = import("mod1");
object square = mod1.attr("square");
int y = extract<int>(square(x));

Upvotes: 1

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