Building Extensions with boost.python

Using bjam

bjam is a standard tool for building boost library itself. Thus it is preferable way to build Python extensions based on ["boost.python"] with bjam. Basic example listed in [http://www.boost.org/libs/python/doc/tutorial/doc/html/python/hello.html tutorial].

However if you want to add external libraries in your extension (that is why you use boost.python, isn't it?), you must add them to the Jamfile:

# NOTE: Change [[VARIABLES]] according to your system

# Specify our location in the boost project hierarchy
subproject libs/python/MyExtension ; ######## if you put your dir in boost hierarchy

# Include definitions needed for Python modules
SEARCH on python.jam = $(BOOST_BUILD_PATH) ;

include python.jam ;

# Declare a Python extension
extension Example
:  # sources
   Example.cpp
   # dependencies
   <dll>../build/boost_python
  
:  # requirements
   <include>[[FULL_PATH_INCLUDE_DIR]]
   <include>[[RELATIVE_PATH_INCLUDE_DIR]]
   <library-file>[[FULL_PATH_AND_LIBNAME]]
   <library-path>[[PATH_TO_LIB]]
   <library-file>[[LIBNAME]]
  ;

# Declare a test for the extension module
boost-python-runtest test1
    :  # Python test driver
    test1.py
    # extension modules to use
    <pyd>Example ;

Keeping your projects under boost hierarchy is often inconvenient. You may build your extension from any place by:

• changing the line subproject in the Jamfile to the

  project-root ;

• remove <dll> line and add to the requirements:

       # link to the appropriate library for the build variant.
      <release><find-library>boost_python
      <debug><find-library>boost_python_debug
      <debug-python><find-library>boost_python_pydebug
    
    # library path required for linking to boost_python shared lib. You
    # may need to edit this for your installation
      <library-path>$(BOOST_ROOT)/libs/python/build/VisualStudio/bin

• creating boost-build.jam file in the root of your project tree like that:

  BOOST_ROOT=[[PATH_TO_BOOST]] ;
  boost-build $(BOOST_ROOT)/tools/build ;

• to silence warning create empty Jamrules file.

Using make

• Make sure to link with boost_python or boost_python_debug library.

Using SCons

You might want to try [http://www.scons.org scons].

It's really easy to build python extensions with scons. Here is an example that would build uvector.so:

BOOST_VERSION = 'boost.cvs'
BOOST = '/usr/local/src/' + BOOST_VERSION
BOOSTLIBPATH = BOOST+'/stage/lib'
env = Environment (LIBPATH=['./',BOOSTLIBPATH], CPPPATH=[BOOST, '/usr/include/python2.3'],  
                   RPATH=['./',BOOSTLIBPATH])
env.SharedLibrary (target='uvector', source='uvector.cc', SHLIBPREFIX='', LIBS=[BOOST_PYTHON_LIB])

Using Windows IDE

• Make sure you keep "Use Managed Extension" == No if you are using Visual Studio.NET.

Tips and tricks

To keep up with bjam rules you might want to have a dry run without actually building anything: {{{bjam -na }}}

To copy resulting executable to desired directory take a look at the stage rule.

To specify library in a platform-independent way you could do something like:

    local libname
    if $(NT)
    {
       libname = foo.lib
    }
    else
    {
       libname = libfoo.a
    }

        ...

    <library-file>$(libname)

in the Jamfile.

Add -DBOOST_PYTHON_STATIC_LIB to your compiler command-line or <define>BOOST_PYTHON_STATIC_LIB to your bjam requirements; that will turn off exporting for win32: __declspec(dllexport).

If you are getting error C1055: compiler limit : out of keys on MS VisualC, try change /ZI (Program database for edit and continue) to /Zi (Program database).

If you are getting error error C1076: compiler limit - internal heap limit reached try add /ZmNNN (with NNN=300..800)

You can use a setup.py file if u are careful

#setup.py
from distutils.core import setup
from distutils.extension import Extension
import os.path
import sys
if sys.platform == "win32" :
    include_dirs = ["C:/Boost/include/boost-1_32","."]
    libraries=["boost_python-mgw"]
    library_dirs=['C:/Boost/lib']
else :
    include_dirs = ["/usr/include/boost-1_32","."]
    libraries=["boost_python-gcc"]
    library_dirs=['/usr/local/lib']

files = ["test.cpp","itest.cpp"]

setup(name="test",    
      ext_modules=[
                    Extension("test",files,
                    library_dirs=library_dirs,
                    libraries=libraries,
                    include_dirs=include_dirs,
                    depends=[]),
                    ]
     )

For the above I compile and install boost using bjam then you set the appropriate paths to your boost header and libs It works on linux and windows with mingw

That way u have nice cross platform build