include

using namespace boost::python;

struct World{
    void set(std::string msg) { this->msg = msg; }
    std::string greet() { return msg; }
    std::string msg;
};

BOOST_PYTHON_MODULE(hello)
{
    class_<World>("World")
        .def("greet", &World::greet)
        .def("set", &World::set)
    ;
}

Compile and build ok

~/boost$ g++ -fPIC -I/usr/include/python2.6 -c hello.cpp 
~/boost$ g++ -shared hello.o -o hello.so

But when import from python side, got error.

>>> import hello.so
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: ./hello.so: undefined symbol: _ZNK5boost6python7objects21py_function_impl_base9max_arityEv
&开发者_如何学Cgt;>> 

Solved this via "No such file or directory" error with Boost Python

g++ -c -fPIC hello.cpp -o hello.o
g++ -shared -Wl,-soname,hello.so -o hello.so  hello.o -lpython2.6 -lboost_python

did the trick for me. I hope this is as clear as possible as i was struggling with this for about half an hour now ;)

same as other post here

g++ -c -fPIC hello.cpp -o hello.o
g++ -shared -Wl,-soname,hello.so -o hello.so  hello.o -lpython2.6 -lboost_python

But i want to stress the importance of the position of "-lpython2.6 -lboost_python". If you put them in front of input files (hello.o), they will be somehow ignored (not linked to the final hello.so). This is at least true for g++ (Ubuntu/Linaro 4.6.3-1ubuntu5).

To be simple, http://ubuntuforums.org/showthread.php?t=496287 suggested:

  g++ <.cpp or .o file(s)> [LDFLAGS] [LIBS] -o [appname]

Oh, I just saw this post:

help needed with boost python

and problem solved

I had the same issue and it turned out that I was missing a constructor on my class.