Discussion:
[C++-sig] Using boost.python with Makefile (no bjam)
Philipp Münzel
2010-10-06 10:33:55 UTC
Permalink
Hi everyone,

thanks to hints on this list I've now got a working build of boost.python.

I built the hello world exmaple (using the jam-file) and ran the
testsuite with success.

Now I want to get used to boost.python by exporting a few functions of a
C++ lib I'm working on. This lib uses make as buildtool. Therefore I
want to know how to setup a Makefile for boost.python.

To start from ground up, I just took the example source code from
libs/python/example/tutorial/hello.cpp and tried to compile and link it
as a shared library. Unfortunately, there remain undefined symbols,
which is why it cannot be loaded as python module.

My boost installation is under /usr/local and is built in system layout
as static libraries (libboost_x.a).

$ cat hello.cpp
// Copyright Joel de Guzman 2002-2004. Distributed under the Boost
// Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt
// or copy at http://www.boost.org/LICENSE_1_0.txt)
// Hello World Example from the tutorial
// [Joel de Guzman 10/9/2002]

#include <boost/python/module.hpp>
#include <boost/python/def.hpp>

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

BOOST_PYTHON_MODULE(hello_ext)
{
using namespace boost::python;
def("greet", greet);
}

$ g++ -I/usr/local/include -I/usr/include/python -fpic -c -o hello.o
hello.cpp
$ g++ -shared -Wl,-soname,"libhello.so" -o libhello.so hello.o
$ nm -u libhello.so
U PyString_Type
w _Jv_RegisterClasses
U _Py_NoneStruct
U _Unwind_Resume@@GCC_3.0
U _ZN5boost6python6detail11init_moduleEPKcPFvvE
U _ZN5boost6python6detail12gcc_demangleEPKc
U
_ZN5boost6python6detail17scope_setattr_docEPKcRKNS0_3api6objectES3_
U
_ZN5boost6python7objects15function_objectERKNS1_11py_functionE
U _ZN5boost6python7objects21py_function_impl_baseD2Ev
U _ZN5boost6python9converter19do_return_to_pythonEPKc
U _ZN5boost6python9converter8registry5queryENS0_9type_infoE
U
_ZNK5boost6python7objects21py_function_impl_base9max_arityEv
U
_ZNK5boost6python9converter12registration25expected_from_python_typeEv
U _ZTIN5boost6python7objects21py_function_impl_baseE
U _ZTIPKc@@CXXABI_1.3
U _ZTIc@@CXXABI_1.3
U _ZTVN10__cxxabiv120__si_class_type_infoE@@CXXABI_1.3
U _ZTVN5boost6python7objects21py_function_impl_baseE
U _ZdlPv@@GLIBCXX_3.4
U _Znwm@@GLIBCXX_3.4
U __cxa_atexit@@GLIBC_2.2.5
w __cxa_finalize@@GLIBC_2.2.5
U __cxa_guard_abort@@CXXABI_1.3
U __cxa_guard_acquire@@CXXABI_1.3
U __cxa_guard_release@@CXXABI_1.3
w __gmon_start__
U __gxx_personality_v0@@CXXABI_1.3
$ python
import libhello
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ImportError: ./libhello.so: undefined symbol:
_ZNK5boost6python7objects21py_function_impl_base9max_arityEv

So what is the big magic of bjam that when bjam links libboost_python.a
I get no undefined symbols, but when i do it "by hand" i get these?

Regards,
Philipp
Philipp Münzel
2010-10-06 10:43:09 UTC
Permalink
Oh crap, the command that links is of course:

$ g++ -shared -Wl,-soname,"libhello.so" -L/usr/local/lib -lboost_python
-o libhello.so hello.o

But I get the undefined symbols nevertheless:
U PyString_Type
w _Jv_RegisterClasses
U _Py_NoneStruct
U _Unwind_Resume@@GCC_3.0
U _ZN5boost6python6detail11init_moduleEPKcPFvvE
U _ZN5boost6python6detail12gcc_demangleEPKc
U
_ZN5boost6python6detail17scope_setattr_docEPKcRKNS0_3api6objectES3_
U _ZN5boost6python7objects15function_objectERKNS1_11py_functionE
U _ZN5boost6python7objects21py_function_impl_baseD2Ev
U _ZN5boost6python9converter19do_return_to_pythonEPKc
U _ZN5boost6python9converter8registry5queryENS0_9type_infoE
U _ZNK5boost6python7objects21py_function_impl_base9max_arityEv
U
_ZNK5boost6python9converter12registration25expected_from_python_typeEv
U _ZTIN5boost6python7objects21py_function_impl_baseE
U _ZTIPKc@@CXXABI_1.3
U _ZTIc@@CXXABI_1.3
U _ZTVN10__cxxabiv120__si_class_type_infoE@@CXXABI_1.3
U _ZTVN5boost6python7objects21py_function_impl_baseE
U _ZdlPv@@GLIBCXX_3.4
U _Znwj@@GLIBCXX_3.4
U __cxa_atexit@@GLIBC_2.1.3
w __cxa_finalize@@GLIBC_2.1.3
U __cxa_guard_abort@@CXXABI_1.3
U __cxa_guard_acquire@@CXXABI_1.3
U __cxa_guard_release@@CXXABI_1.3
w __gmon_start__
U __gxx_personality_v0@@CXXABI_1.3
Charles Solar
2010-10-06 13:30:20 UTC
Permalink
You need to link with libpython as well. libpython should resolve these.
Post by Philipp Münzel
$ g++ -shared -Wl,-soname,"libhello.so" -L/usr/local/lib -lboost_python
-o libhello.so hello.o
U PyString_Type
? ? ? ? w _Jv_RegisterClasses
? ? ? ? U _Py_NoneStruct
? ? ? ? U _ZN5boost6python6detail11init_moduleEPKcPFvvE
? ? ? ? U _ZN5boost6python6detail12gcc_demangleEPKc
? ? ? ? U
_ZN5boost6python6detail17scope_setattr_docEPKcRKNS0_3api6objectES3_
? ? ? ? U _ZN5boost6python7objects15function_objectERKNS1_11py_functionE
? ? ? ? U _ZN5boost6python7objects21py_function_impl_baseD2Ev
? ? ? ? U _ZN5boost6python9converter19do_return_to_pythonEPKc
? ? ? ? U _ZN5boost6python9converter8registry5queryENS0_9type_infoE
? ? ? ? U _ZNK5boost6python7objects21py_function_impl_base9max_arityEv
? ? ? ? U
_ZNK5boost6python9converter12registration25expected_from_python_typeEv
? ? ? ? U _ZTIN5boost6python7objects21py_function_impl_baseE
? ? ? ? U _ZTVN5boost6python7objects21py_function_impl_baseE
? ? ? ? w __gmon_start__
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Philipp Münzel
2010-10-06 14:07:05 UTC
Permalink
I added -lpython2.6 to the linker command, but I didn't change anything.
Obviously, the missing symbols are boost symbols and not python symbols,
since their names
_ZN5boost6python6detail11init_moduleEPKcPFvvE
clearly refer boost.

I built boost_python with the following command:

sudo ./bjam install -q --layout=system --with-python toolset=gcc
variant=release link=static threading=multi runtime-link=static

What is missing here?

Philipp
Post by Charles Solar
You need to link with libpython as well. libpython should resolve these.
Post by Philipp Münzel
$ g++ -shared -Wl,-soname,"libhello.so" -L/usr/local/lib -lboost_python
-o libhello.so hello.o
U PyString_Type
w _Jv_RegisterClasses
U _Py_NoneStruct
U _ZN5boost6python6detail11init_moduleEPKcPFvvE
U _ZN5boost6python6detail12gcc_demangleEPKc
U
_ZN5boost6python6detail17scope_setattr_docEPKcRKNS0_3api6objectES3_
U _ZN5boost6python7objects15function_objectERKNS1_11py_functionE
U _ZN5boost6python7objects21py_function_impl_baseD2Ev
U _ZN5boost6python9converter19do_return_to_pythonEPKc
U _ZN5boost6python9converter8registry5queryENS0_9type_infoE
U _ZNK5boost6python7objects21py_function_impl_base9max_arityEv
U
_ZNK5boost6python9converter12registration25expected_from_python_typeEv
U _ZTIN5boost6python7objects21py_function_impl_baseE
U _ZTVN5boost6python7objects21py_function_impl_baseE
w __gmon_start__
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