compile some code with boost.python by mingw in wi

Question

I decided to make my program compatible with windows environment.But I have very little programming experience on windows.There are some errors need help.

Environment:

• os: win7-64bit,
• ide: codeblocks12.11,
• python: Python 2.7.3 Windows X86-64 Installer (Windows AMD64 / Intel 64 / X86-64 binary [1] -- does not include source)
• compiler: mingw that come from codeblocks installation package.
• boost: boost1.52

I only copy and test this "hello" code that come from ".\boost_1_52_0\libs\python\example\tutorial"

Code:

#include <iostream>
#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);
}

using namespace std;
int main()
{
    cout << "Hello world!" << endl;
    return 0;
}

Error info:

mingw32-g++.exe -Wall -fexceptions  -g  -ID:\boost\include\boost-1_52 -IC:\Python27\include  -c E:\project\snail-MW\test1\main.cpp -o obj\Debug\main.o
mingw32-g++.exe -LD:\boost\lib\ -LC:\Python27\libs  -o bin\Debug\test1.exe obj\Debug\main.o  
obj\Debug\main.o: In function `inithello_ext':
E:/project/snail-MW/test1/main.cpp:11: undefined reference to `boost::python::detail::init_module(char const*, void (*)())'
obj\Debug\main.o: In function `ZNK5boost6python9type_info4nameEv':
D:/boost/include/boost-1_52/boost/python/type_id.hpp:165: undefined reference to `boost::python::detail::gcc_demangle(char const*)'
obj\Debug\main.o: In function `ZNK5boost6python15to_python_valueIRKPKcEclES5_':
D:/boost/include/boost-1_52/boost/python/converter/builtin_converters.hpp:161: undefined reference to `boost::python::converter::do_return_to_python(char const*)'
................

It have also do some errors that only compile by the command of "bjam toolset=gcc variant=release " in the station ".\boost_1_52_0\libs\python\example\tutorial".

Answer 1

You got the paths, but you're not linking against the boost and python library:

-lboost_python -lpython27

Also you're trying to create an executable (that's why you had to add a main() to the example in order to compile it). For python modules, you want to create a shared library, matching the name defined by the BOOST_PYTHON_MODULE(...) macro. The extension of these modules should be .pyd.

-shared -o hello_ext.pyd

If the linker can't find the boost_python library, check your boost library directory. Depending on your installation, you should have a libboost_python.a or libboost_python-mgw??-mt-1_??.a. If you can't find anything like that, you have to build them first. You should decide if you want to build static or shared libraries. More details here.

c:\boost_1_52> b2 toolset=gcc --with-python

This will fail if boost can't find your python installation. To configure (usually a non-standard location of) python, edit the user-config.jam. This may be in your %HOMEDRIVE%%HOMEPATH% or boost_1_52_0\tools\build\v2. Locate Python configuration in that file and set the proper paths (if python was installed at the default location, this step shouldn't be required). The syntax is:

using python : python_version : python_base : python_incl : python_lib ;

For example:

using python : 2.7 : c:/Python27 : c:/Python27/include : c:/Python27/libs ;

If you choose to build the static boost python library, you may get other errors when linking your program. If that's the case, you have to indicate that you want to link against the static library with:

-DBOOST_PYTHON_STATIC_LIB

Lastly, the compiler may complain about ::hypot not being declared. To fix that, #include <cmath> before including the boost/python headers.

Answer 2

To make the tutorial run on Boost 1_60_0, on Windows 7, with a 64 bit mingw gcc (version 4.8.1), I needed to use the commands in an msys shell:

rm -rf bin.v2/libs/python stage/lib/libboost_python-mgw48-*
./b2.exe toolset=gcc define=MS_WIN64 --with-python link=static

to make the boost python library. This command shall be executed in the Boost root directory. Note that without the define=MS_WIN64 I get undefined errors on __imp_py_InitModule4 as indicated in Python extensions for Win64 via GCC.

After that, it is straightforward to compile the Python boost tutorial:

g++ hello.cpp -I /c/projects/boost_1_60_0/ -I /c/prog64/Python27/include -DBOOST_PYTHON_STATIC_LIB  /c/projects/boost_1_60_0/stage/lib/libboost_python-mgw48-mt-1_60.a /c/prog64/Python27/python27.dll -DMS_WIN64 -shared -o hello_ext.pyd

This also worked for Boost 1_54_0