BOOST Python

Question

Hi Folks, I have problems with Boost Python!!
Here is my sourcecode:
char const* greet()
return "hello, world";
#include <boost/python.hpp>
BOOST_PYTHON_MODULE(hello_ext)
using namespace boost::python;
def("greet", greet);
When I compile this with gcc, I will get the following error:
In file included from /usr/include/boost/python/detail/prefix.hpp:13:0,
from /usr/include/boost/python/args.hpp:8,
from /usr/include/boost/python.hpp:11,
from test.cxx:1:
/usr/include/boost/python/detail/wrap_python.hpp:50:23: fatal error: pyconfig.h: No such file or directory
# include <pyconfig.h>
If I now specify the path to pyconfig, it will get even worse:
gcc -I/usr/local/include/python3.3/ test.cxx -o test
Because I get:
/usr/lib/gcc/x87_64-unknown-linux-gnu/4.8.2/../../../../lib/crt1.o: In function `_start':
(.text+0x20): undefined reference to `main'
/tmp/ccnN7atN.o: In function `PyInit_hello_ext':
test.cxx:(.text+0x21): undefined reference to `__cxa_guard_acquire'
test.cxx:(.text+0x7a): undefined reference to `__cxa_guard_release'
test.cxx:(.text+0x89): undefined reference to `boost::python::detail::init_module(PyModuleDef&, void (*)())'
/tmp/ccnN7atN.o: In function `__static_initialization_and_destruction_0(int, int)':
test.cxx:(.text+0xcf): undefined reference to `std::ios_base::Init::Init()'
test.cxx:(.text+0xde): undefined reference to `std::ios_base::Init::~Init()'
/tmp/ccnN7atN.o: In function `boost::python::type_info::name() const':
test.cxx:(.text._ZNK5boost6python9type_info4nameEv[_ZNK5boost6python9type_info4nameEv]+0x1f): undefined reference to `boost::python::detail::gcc_demangle(char const*)'
/tmp/ccnN7atN.o: In function `boost::python::to_python_value<char const* const&>::operator()(char const* const&) const':
test.cxx:(.text._ZNK5boost6python15to_python_valueIRKPKcEclES5_[_ZNK5boost6python15to_python_valueIRKPKcEclES5_]+0x1b): undefined reference to `boost::python::converter::do_return_to_python(char const*)'
/tmp/ccnN7atN.o: In function `boost::python::to_python_value<char const* const&>::get_pytype() const':
test.cxx:(.text._ZNK5boost6python15to_python_valueIRKPKcE10get_pytypeEv[_ZNK5boost6python15to_python_valueIRKPKcE10get_pytypeEv]+0x9): undefined reference to `PyUnicode_Type'
/tmp/ccnN7atN.o: In function `boost::python::api::object::object()':
test.cxx:(.text._ZN5boost6python3api6objectC2Ev[_ZN5boost6python3api6objectC5Ev]+0xd): undefined reference to `_Py_NoneStruct'
/tmp/ccnN7atN.o: In function `void boost::python::def<char const* (*)()>(char const*, char const* (*)())':
test.cxx:(.text._ZN5boost6python3defIPFPKcvEEEvS3_T_[_ZN5boost6python3defIPFPKcvEEEvS3_T_]+0x41): undefined reference to `boost::python::detail::scope_setattr_doc(char const*, boost::python::api::object const&, char const*)'
/tmp/ccnN7atN.o: In function `boost::python::api::object boost::python::detail::make_function_aux<char const* (*)(), boost::python::default_call_policies, boost::mpl::vector1<char const*> >(char const* (*)(), boost::python::default_call_policies const&, boost::mpl::vector1<char const*> const&)':
test.cxx:(.text._ZN5boost6python6detail17make_function_auxIPFPKcvENS0_21default_call_policiesENS_3mpl7vector1IS4_EEEENS0_3api6objectET_RKT0_RKT1_[_ZN5boost6python6detail17make_function_auxIPFPKcvENS0_21default_call_policiesENS_3mpl7vector1IS4_EEEENS0_3api6objectET_RKT0_RKT1_]+0x52): undefined reference to `boost::python::objects::function_object(boost::python::objects::py_function const&)'
/tmp/ccnN7atN.o: In function `boost::python::objects::py_function::py_function<boost::python::detail::caller<char const* (*)(), boost::python::default_call_policies, boost::mpl::vector1<char const*> > >(boost::python::detail::caller<char const* (*)(), boost::python::default_call_policies, boost::mpl::vector1<char const*> > const&)':
test.cxx:(.text._ZN5boost6python7objects11py_functionC2INS0_6detail6callerIPFPKcvENS0_21default_call_policiesENS_3mpl7vector1IS7_EEEEEERKT_[_ZN5boost6python7objects11py_functionC5INS0_6detail6callerIPFPKcvENS0_21default_call_policiesENS_3mpl7vector1IS7_EEEEEERKT_]+0x19): undefined reference to `operator new(unsigned long)'
test.cxx:(.text._ZN5boost6python7objects11py_functionC2INS0_6detail6callerIPFPKcvENS0_21default_call_policiesENS_3mpl7vector1IS7_EEEEEERKT_[_ZN5boost6python7objects11py_functionC5INS0_6detail6callerIPFPKcvENS0_21default_call_policiesENS_3mpl7vector1IS7_EEEEEERKT_]+0x47): undefined reference to `operator delete(void*)'
/tmp/ccnN7atN.o: In function `boost::python::objects::py_function_impl_base::py_function_impl_base()':
test.cxx:(.text._ZN5boost6python7objects21py_function_impl_baseC2Ev[_ZN5boost6python7objects21py_function_impl_baseC5Ev]+0xf): undefined reference to `vtable for boost::python::objects::py_function_impl_base'
/tmp/ccnN7atN.o:(.rodata._ZTVN5boost6python7objects23caller_py_function_implINS0_6detail6callerIPFPKcvENS0_21default_call_policiesENS_3mpl7vector1IS6_EEEEEE[_ZTVN5boost6python7objects23caller_py_function_implINS0_6detail6callerIPFPKcvENS0_21default_call_policiesENS_3mpl7vector1IS6_EEEEEE]+0x30): undefined reference to `boost::python::objects::py_function_impl_base::max_arity() const'
/tmp/ccnN7atN.o: In function `boost::python::objects::caller_py_function_impl<boost::python::detail::caller<char const* (*)(), boost::python::default_call_policies, boost::mpl::vector1<char const*> > >::~caller_py_function_impl()':
test.cxx:(.text._ZN5boost6python7objects23caller_py_function_implINS0_6detail6callerIPFPKcvENS0_21default_call_policiesENS_3mpl7vector1IS6_EEEEED2Ev[_ZN5boost6python7objects23caller_py_function_implINS0_6detail6callerIPFPKcvENS0_21default_call_policiesENS_3mpl7vector1IS6_EEEEED5Ev]+0x1f): undefined reference to `boost::python::objects::py_function_impl_base::~py_function_impl_base()'
test.cxx:(.text._ZN5boost6python7objects23caller_py_function_implINS0_6detail6callerIPFPKcvENS0_21default_call_policiesENS_3mpl7vector1IS6_EEEEED2Ev[_ZN5boost6python7objects23caller_py_function_implINS0_6detail6callerIPFPKcvENS0_21default_call_policiesENS_3mpl7vector1IS6_EEEEED5Ev]+0x34): undefined reference to `operator delete(void*)'
/tmp/ccnN7atN.o: In function `boost::python::objects::caller_py_function_impl<boost::python::detail::caller<char const* (*)(), boost::python::default_call_policies, boost::mpl::vector1<char const*> > >::~caller_py_function_impl()':
test.cxx:(.text._ZN5boost6python7objects23caller_py_function_implINS0_6detail6callerIPFPKcvENS0_21default_call_policiesENS_3mpl7vector1IS6_EEEEED0Ev[_ZN5boost6python7objects23caller_py_function_implINS0_6detail6callerIPFPKcvENS0_21default_call_policiesENS_3mpl7vector1IS6_EEEEED0Ev]+0x20): undefined reference to `operator delete(void*)'
/tmp/ccnN7atN.o:(.rodata._ZTIN5boost6python7objects23caller_py_function_implINS0_6detail6callerIPFPKcvENS0_21default_call_policiesENS_3mpl7vector1IS6_EEEEEE[_ZTIN5boost6python7objects23caller_py_function_implINS0_6detail6callerIPFPKcvENS0_21default_call_policiesENS_3mpl7vector1IS6_EEEEEE]+0x0): undefined reference to `vtable for __cxxabiv1::__si_class_type_info'
/tmp/ccnN7atN.o:(.rodata._ZTIN5boost6python7objects23caller_py_function_implINS0_6detail6callerIPFPKcvENS0_21default_call_policiesENS_3mpl7vector1IS6_EEEEEE[_ZTIN5boost6python7objects23caller_py_function_implINS0_6detail6callerIPFPKcvENS0_21default_call_policiesENS_3mpl7vector1IS6_EEEEEE]+0x10): undefined reference to `typeinfo for boost::python::objects::py_function_impl_base'
/tmp/ccnN7atN.o: In function `boost::python::detail::caller_arity<0u>::impl<char const* (*)(), boost::python::default_call_policies, boost::mpl::vector1<char const*> >::signature()':
test.cxx:(.text._ZN5boost6python6detail12caller_arityILj0EE4implIPFPKcvENS0_21default_call_policiesENS_3mpl7vector1IS6_EEE9signatureEv[_ZN5boost6python6detail12caller_arityILj0EE4implIPFPKcvENS0_21default_call_policiesENS_3mpl7vector1IS6_EEE9signatureEv]+0x26): undefined reference to `__cxa_guard_acquire'
test.cxx:(.text._ZN5boost6python6detail12caller_arityILj0EE4implIPFPKcvENS0_21default_call_policiesENS_3mpl7vector1IS6_EEE9signatureEv[_ZN5boost6python6detail12caller_arityILj0EE4implIPFPKcvENS0_21default_call_policiesENS_3mpl7vector1IS6_EEE9signatureEv]+0x5a): undefined reference to `__cxa_guard_release'
test.cxx:(.text._ZN5boost6python6detail12caller_arityILj0EE4implIPFPKcvENS0_21default_call_policiesENS_3mpl7vector1IS6_EEE9signatureEv[_ZN5boost6python6detail12caller_arityILj0EE4implIPFPKcvENS0_21default_call_policiesENS_3mpl7vector1IS6_EEE9signatureEv]+0x95): undefined reference to `__cxa_guard_abort'
/tmp/ccnN7atN.o: In function `boost::python::detail::signature_arity<0u>::impl<boost::mpl::vector1<char const*> >::elements()':
test.cxx:(.text._ZN5boost6python6detail15signature_arityILj0EE4implINS_3mpl7vector1IPKcEEE8elementsEv[_ZN5boost6python6detail15signature_arityILj0EE4implINS_3mpl7vector1IPKcEEE8elementsEv]+0x1d): undefined reference to `__cxa_guard_acquire'
test.cxx:(.text._ZN5boost6python6detail15signature_arityILj0EE4implINS_3mpl7vector1IPKcEEE8elementsEv[_ZN5boost6python6detail15signature_arityILj0EE4implINS_3mpl7vector1IPKcEEE8elementsEv]+0x51): undefined reference to `__cxa_guard_release'
test.cxx:(.text._ZN5boost6python6detail15signature_arityILj0EE4implINS_3mpl7vector1IPKcEEE8elementsEv[_ZN5boost6python6detail15signature_arityILj0EE4implINS_3mpl7vector1IPKcEEE8elementsEv]+0x69): undefined reference to `__cxa_guard_abort'
/tmp/ccnN7atN.o: In function `boost::python::type_info boost::python::type_id<char const*>()':
test.cxx:(.text._ZN5boost6python7type_idIPKcEENS0_9type_infoEv[_ZN5boost6python7type_idIPKcEENS0_9type_infoEv]+0xd): undefined reference to `typeinfo for char const*'
/tmp/ccnN7atN.o: In function `boost::python::converter::expected_pytype_for_arg<char const*>::get_pytype()':
test.cxx:(.text._ZN5boost6python9converter23expected_pytype_for_argIPKcE10get_pytypeEv[_ZN5boost6python9converter23expected_pytype_for_argIPKcE10get_pytypeEv]+0x1b): undefined reference to `boost::python::converter::registry::query(boost::python::type_info)'
test.cxx:(.text._ZN5boost6python9converter23expected_pytype_for_argIPKcE10get_pytypeEv[_ZN5boost6python9converter23expected_pytype_for_argIPKcE10get_pytypeEv]+0x32): undefined reference to `boost::python::converter::registration::expected_from_python_type() const'
/tmp/ccnN7atN.o: In function `boost::python::type_info boost::python::type_id<char>()':
test.cxx:(.text._ZN5boost6python7type_idIcEENS0_9type_infoEv[_ZN5boost6python7type_idIcEENS0_9type_infoEv]+0xd): undefined reference to `typeinfo for char'
/tmp/ccnN7atN.o:(.eh_frame+0x42b): undefined reference to `__gxx_personality_v0'
collect2: error: ld returned 1 exit status
Shit happens but what I can I do now. The bad thing is also that I need this library as dependecy for graph-tool, therefore it is necessary that for it to work without user specified path during compilation!

Answer 1

brewlius_cesar wrote:
Well, pks is half right I believe.  Well maybe one third.
I assumed the poster was writing a python extension module, which is similar to a shared library.  Shared libraries should not have a function called main with any signature.
Second, you are not required to resolve undefined symbols when linking a shared library.  Only when you link against a final executable.
That said, pks is probably right for this particular circumstance.  You should link your extension module against boost python.  This is because there is no executable going to be built from your library, it is simply going to be loaded dynamically by Python and Python will not know how/where to get the necessarry libs for boost.
This last part may not be required, some boost libraries are entirely included in the header file, and do not require you to link against a shared library.
Well, I am not familiar with boost::python at all, just with generic C programming. So if you want to create a shared object you're correct.