configure.ac_snippet

#configure.ac snippet
#copy paste into your own configure.ac file

#check for swig
AC_CHECK_PROGS([SWIG],[swig],["noswig"])

#present configure with a command-line option to disable the python bindings
AC_ARG_ENABLE([python],[AS_HELP_STRING([--disable-python],[build without the python bindings])],[enable_python=$enableval],[enable_python=check])
#default behavior is to install the python bindings into subfolders of $prefix
#however, this may require the user to set the PYTHONPATH environment variable
#in order to avoid this, invoke configure with the --enable-python-integration option

AC_ARG_ENABLE([python-integration],[AS_HELP_STRING([--enable-python-integration],[install the python bindings in the interpreters site-packages folder])],[enable_python_integration=$enableval],[enable_python_integration=check])

VALID_PYTHON=

if test "x$SWIG" = xnoswig && test "x$enable_python" = xyes ; then
        #don't even bother when swig is not found
        AC_MSG_ERROR([--enable-python was given as an option but swig was not found on the system])
elif test "x$SWIG" = xswig && test "x$enable_python" != xno ; then
        #verify the python installation
        AM_PATH_PYTHON(,[PYTHON_FOUND=true],[PYTHON_FOUND=false])
        if test "x$PYTHON_FOUND" = xtrue ; then
                PYTHON_CPPFLAGS=
                PYTHON_LDFLAGS=
                AX_PYTHON_DEVEL
                if test "x$PYTHON" = x ; then
                        if test "x$enable_python" = xyes ; then
                                AC_MSG_ERROR([Incomplete python development package])
                        else
                                AC_MSG_WARN([Incomplete python development package])
                        fi
                        VALID_PYTHON=no
                else
                        VALID_PYTHON=yes
                fi

        fi
fi


if test "x$VALID_PYTHON" = xyes ; then
	AC_MSG_NOTICE([Building with Python bindings])


	if test "x$enable_python_integration" = xyes ; then
        	pythondir=$PYTHON_SITE_PKG
        	pyexecdir=$PYTHON_SITE_PKG_EXEC
	fi


	AC_SUBST(PYTHONDIR,$pythondir)
	AC_SUBST(PKGPYTHONDIR,$pkgpythondir)
	AC_SUBST(PYEXECDIR,$pyexecdir)
	AC_SUBST(PKGPYEXECDIR,$pkgpyexecdir)
fi

AM_CONDITIONAL([ENABLE_PYTHON],[test x$VALID_PYTHON = xyes])

m4-ax_python_devel.m4

# Modified by Tom Schoonjans

# ===========================================================================
#      http://www.gnu.org/software/autoconf-archive/ax_python_devel.html
# ===========================================================================
#
# SYNOPSIS
#
#   AX_PYTHON_DEVEL([version])
#
# DESCRIPTION
#
#   Note: Defines as a precious variable "PYTHON_VERSION". Don't override it
#   in your configure.ac.
#
#   This macro checks for Python and tries to get the include path to
#   'Python.h'. It provides the $(PYTHON_CPPFLAGS) and $(PYTHON_LDFLAGS)
#   output variables. It also exports $(PYTHON_EXTRA_LIBS) and
#   $(PYTHON_EXTRA_LDFLAGS) for embedding Python in your code.
#
#   You can search for some particular version of Python by passing a
#   parameter to this macro, for example ">= '2.3.1'", or "== '2.4'". Please
#   note that you *have* to pass also an operator along with the version to
#   match, and pay special attention to the single quotes surrounding the
#   version number. Don't use "PYTHON_VERSION" for this: that environment
#   variable is declared as precious and thus reserved for the end-user.
#
#   This macro should work for all versions of Python >= 2.1.0. As an end
#   user, you can disable the check for the python version by setting the
#   PYTHON_NOVERSIONCHECK environment variable to something else than the
#   empty string.
#
#   If you need to use this macro for an older Python version, please
#   contact the authors. We're always open for feedback.
#
# LICENSE
#
#   Copyright (c) 2009 Sebastian Huber <sebastian-huber@web.de>
#   Copyright (c) 2009 Alan W. Irwin
#   Copyright (c) 2009 Rafael Laboissiere <rafael@laboissiere.net>
#   Copyright (c) 2009 Andrew Collier
#   Copyright (c) 2009 Matteo Settenvini <matteo@member.fsf.org>
#   Copyright (c) 2009 Horst Knorr <hk_classes@knoda.org>
#   Copyright (c) 2013 Daniel Mullner <muellner@math.stanford.edu>
#
#   This program is free software: you can redistribute it and/or modify it
#   under the terms of the GNU General Public License as published by the
#   Free Software Foundation, either version 3 of the License, or (at your
#   option) any later version.
#
#   This program is distributed in the hope that it will be useful, but
#   WITHOUT ANY WARRANTY; without even the implied warranty of
#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
#   Public License for more details.
#
#   You should have received a copy of the GNU General Public License along
#   with this program. If not, see <http://www.gnu.org/licenses/>.
#
#   As a special exception, the respective Autoconf Macro's copyright owner
#   gives unlimited permission to copy, distribute and modify the configure
#   scripts that are the output of Autoconf when processing the Macro. You
#   need not follow the terms of the GNU General Public License when using
#   or distributing such scripts, even though portions of the text of the
#   Macro appear in them. The GNU General Public License (GPL) does govern
#   all other use of the material that constitutes the Autoconf Macro.
#
#   This special exception to the GPL applies to versions of the Autoconf
#   Macro released by the Autoconf Archive. When you make and distribute a
#   modified version of the Autoconf Macro, you may extend this special
#   exception to the GPL to apply to your modified version as well.

#serial 16

AU_ALIAS([AC_PYTHON_DEVEL], [AX_PYTHON_DEVEL])
AC_DEFUN([AX_PYTHON_DEVEL],[
	#
	# Allow the use of a (user set) custom python version
	#
	AC_ARG_VAR([PYTHON_VERSION],[The installed Python
		version to use, for example '2.3'. This string
		will be appended to the Python interpreter
		canonical name.])

	AC_PATH_PROG([PYTHON],[python[$PYTHON_VERSION]])
	if test -z "$PYTHON"; then
	   AC_MSG_WARN([Cannot find python$PYTHON_VERSION in your system path])
	   PYTHON_VERSION=""
	   PYTHON=""
	fi

	#
	# Check for a version of Python >= 2.1.0
	#
	AC_MSG_CHECKING([for a version of Python >= '2.1.0'])
	ac_supports_python_ver=`$PYTHON -c "import sys; \
		ver = sys.version.split ()[[0]]; \
		print (ver >= '2.1.0')"`
	if test "$ac_supports_python_ver" != "True"; then
		if test -z "$PYTHON_NOVERSIONCHECK"; then
			AC_MSG_RESULT([no])
			AC_MSG_WARN([
This version of the AC@&t@_PYTHON_DEVEL macro
doesn't work properly with versions of Python before
2.1.0. You may need to re-run configure, setting the
variables PYTHON_CPPFLAGS, PYTHON_LDFLAGS, PYTHON_SITE_PKG,
PYTHON_EXTRA_LIBS and PYTHON_EXTRA_LDFLAGS by hand.
Moreover, to disable this check, set PYTHON_NOVERSIONCHECK
to something else than an empty string.
])
			PYTHON=""
			PYTHON_VERSION=""
		else
			AC_MSG_RESULT([skip at user request])
		fi
	else
		AC_MSG_RESULT([yes])
	fi

	#
	# if the macro parameter ``version'' is set, honour it
	#
	if test x$PYTHON != x ; then
	if test -n "$1"; then
		AC_MSG_CHECKING([for a version of Python $1])
		ac_supports_python_ver=`$PYTHON -c "import sys; \
			ver = sys.version.split ()[[0]]; \
			print (ver $1)"`
		if test "$ac_supports_python_ver" = "True"; then
		   AC_MSG_RESULT([yes])
		else
			AC_MSG_RESULT([no])
			AC_MSG_WARN([this package requires Python $1.
If you have it installed, but it isn't the default Python
interpreter in your system path, please pass the PYTHON_VERSION
variable to configure. See ``configure --help'' for reference.
])
			PYTHON_VERSION=""
			PYTHON=""
		fi
	fi
	fi

	#
	# Check if you have distutils, else fail
	#
	if test x$PYTHON != x ; then
	AC_MSG_CHECKING([for the distutils Python package])
	ac_distutils_result=`$PYTHON -c "import distutils" 2>&1`
	if test -z "$ac_distutils_result"; then
		AC_MSG_RESULT([yes])
	else
		AC_MSG_RESULT([no])
		AC_MSG_WARN([cannot import Python module "distutils".
Please check your Python installation. The error was:
$ac_distutils_result])
		PYTHON_VERSION=""
		PYTHON=""
	fi
	fi

	#
	# Check for Python include path
	#
	if test x$PYTHON != x ; then
	AC_MSG_CHECKING([for Python include path])
	if test -z "$PYTHON_CPPFLAGS"; then
		python_path=`$PYTHON -c "import distutils.sysconfig; \
			print (distutils.sysconfig.get_python_inc ());"`
		plat_python_path=`$PYTHON -c "import distutils.sysconfig; \
			print (distutils.sysconfig.get_python_inc (plat_specific=1));"`
		if test -n "${python_path}"; then
			if test "${plat_python_path}" != "${python_path}"; then
				python_path="-I$python_path -I$plat_python_path"
			else
				python_path="-I$python_path"
			fi
		fi
		PYTHON_CPPFLAGS=$python_path
	fi
	AC_MSG_RESULT([$PYTHON_CPPFLAGS])
	AC_SUBST([PYTHON_CPPFLAGS])
	fi

	#
	# Check for Python library path
	#
	if test x$PYTHON != x ; then
	AC_MSG_CHECKING([for Python library path])
	if test -z "$PYTHON_LDFLAGS"; then
		# (makes two attempts to ensure we've got a version number
		# from the interpreter)
		ac_python_version=`cat<<EOD | $PYTHON -

# join all versioning strings, on some systems
# major/minor numbers could be in different list elements
from distutils.sysconfig import *
e = get_config_var('VERSION')
if e is not None:
	print(e)
EOD`

		if test -z "$ac_python_version"; then
			if test -n "$PYTHON_VERSION"; then
				ac_python_version=$PYTHON_VERSION
			else
				ac_python_version=`$PYTHON -c "import sys; \
					print (sys.version[[:3]])"`
			fi
		fi

		# Make the versioning information available to the compiler
		AC_DEFINE_UNQUOTED([HAVE_PYTHON], ["$ac_python_version"],
                                   [If available, contains the Python version number currently in use.])

		# First, the library directory:
		ac_python_libdir=`cat<<EOD | $PYTHON -

# There should be only one
import distutils.sysconfig
e = distutils.sysconfig.get_config_var('LIBDIR')
if e is not None:
	print (e)
EOD`

		# Now, for the library:
		ac_python_library=`cat<<EOD | $PYTHON -

import distutils.sysconfig
c = distutils.sysconfig.get_config_vars()
if 'LDVERSION' in c:
	print ('python'+c[['LDVERSION']])
else:
	print ('python'+c[['VERSION']])
EOD`

		# This small piece shamelessly adapted from PostgreSQL python macro;
		# credits goes to momjian, I think. I'd like to put the right name
		# in the credits, if someone can point me in the right direction... ?
		#
		#if test -n "$ac_python_libdir" -a -n "$ac_python_library"
		#then
			# use the official shared library
			ac_python_library=`echo "$ac_python_library" | sed "s/^lib//"`
			PYTHON_LDFLAGS="-L$ac_python_libdir -l$ac_python_library"
		#else
		#	# old way: use libpython from python_configdir
		#	ac_python_libdir=`$PYTHON -c \
		#	  "from distutils.sysconfig import get_python_lib as f; \
		#	  import os; \
		#	  print (os.path.join(f(plat_specific=1, standard_lib=1), 'config'));"`
		#	PYTHON_LDFLAGS="-L$ac_python_libdir -lpython$ac_python_version"
		#fi

		if test -z "PYTHON_LDFLAGS"; then
			AC_MSG_WARN([
  Cannot determine location of your Python DSO. Please check it was installed with
  dynamic libraries enabled, or try setting PYTHON_LDFLAGS by hand.
			])
			PYTHON=""
			PYTHON_VERSION=""
		fi
	fi
	AC_MSG_RESULT([$PYTHON_LDFLAGS])
	AC_SUBST([PYTHON_LDFLAGS])
	fi

	#
	# Check for site packages
	#
	if test x$PYTHON != x ; then
	AC_MSG_CHECKING([for Python site-packages path])
	if test -z "$PYTHON_SITE_PKG"; then
		PYTHON_SITE_PKG=`$PYTHON -c "import distutils.sysconfig; \
			print (distutils.sysconfig.get_python_lib(0,0));"`
	fi
	AC_MSG_RESULT([$PYTHON_SITE_PKG])
	AC_SUBST([PYTHON_SITE_PKG])

	#
	# Check for site exec packages
	#
	AC_MSG_CHECKING([for Python site-packages extension modules path])
	if test -z "$PYTHON_SITE_PKG_EXEC"; then
		PYTHON_SITE_PKG_EXEC=`$PYTHON -c "import distutils.sysconfig; \
		        print (distutils.sysconfig.get_python_lib(1,0));"`
	fi
	AC_MSG_RESULT([$PYTHON_SITE_PKG_EXEC])
	AC_SUBST([PYTHON_SITE_PKG_EXEC])

	#
	# Check for package building cflags 
	#
	AC_MSG_CHECKING([for Python module cflags])
	if test -z "$PYTHON_CFLAGS"; then
		PYTHON_CFLAGS=[`$PYTHON -c "import distutils.sysconfig; \
		        conf = distutils.sysconfig.get_config_vars(); \
			print (conf['OPT'])"`]
	fi
	AC_MSG_RESULT([$PYTHON_CFLAGS])
	AC_SUBST([PYTHON_CFLAGS])


	#
	# libraries which must be linked in when embedding
	#
	#AC_MSG_CHECKING(python extra libraries)
	#if test -z "$PYTHON_EXTRA_LIBS"; then
	#   PYTHON_EXTRA_LIBS=`$PYTHON -c "import distutils.sysconfig; \
        #        conf = distutils.sysconfig.get_config_var; \
        #        print (conf('LIBS'))"`
	#fi
	#AC_MSG_RESULT([$PYTHON_EXTRA_LIBS])
	#AC_SUBST(PYTHON_EXTRA_LIBS)

	#
	# final check to see if everything compiles alright
	#
	AC_MSG_CHECKING([consistency of all components of python development environment])
	# save current global flags
	ac_save_LIBS="$LIBS"
	ac_save_CPPFLAGS="$CPPFLAGS"
	LIBS="$ac_save_LIBS $PYTHON_LDFLAGS $PYTHON_EXTRA_LIBS"
	CPPFLAGS="$ac_save_CPPFLAGS $PYTHON_CPPFLAGS"
	AC_LANG_PUSH([C])
	AC_LINK_IFELSE([
		AC_LANG_PROGRAM([[#include <Python.h>]],
				[[Py_Initialize();]])
		],[pythonexists=yes],[pythonexists=no])
	AC_LANG_POP([C])
	# turn back to default flags
	CPPFLAGS="$ac_save_CPPFLAGS"
	LIBS="$ac_save_LIBS"

	AC_MSG_RESULT([$pythonexists])

        if test ! "x$pythonexists" = "xyes"; then
	   AC_MSG_WARN([
  Could not link test program to Python. Maybe the main Python library has been
  installed in some non-standard library path.
  ============================================================================
   ERROR!
   You probably have to install the development version of the Python package
   for your distribution.  The exact name of this package varies among them.
  ============================================================================
	   ])
	  PYTHON_VERSION=""
	  PYTHON=""
	fi
	fi

	#
	# all done!
	#
])

Makefile.am

#python bindings will only be built if all buildtools are available, hence the following automake conditional
if ENABLE_PYTHON
#our python extension module
pyexec_LTLIBRARIES = _mytest.la
_mytest_la_CFLAGS = $(PYTHON_CFLAGS) -I$(top_srcdir)/include $(PYTHON_CPPFLAGS)
#link to the C-library
#probably on Windows one will need to link against the python dll as well
_mytest_la_LIBADD = ../src/mytest.la
#the source code for our extensions module
#nodist because this file will be generated by swig
nodist__mytest_la_SOURCES = mytest_wrap.c
#-module forces libtool to generate a dynamically loadable module
_mytest_la_LDFLAGS = -avoid-version -module -shared -export-dynamic


#nodist because this file will be generated by swig
nodist_python_PYTHON = mytest.py

#this line assumes that the swig interface file mytest.i is located in the src subdirectory
mytest_wrap.c: $(top_srcdir)/src/mytest.i
	$(SWIG) -I${top_srcdir}/include -includeall -o mytest_wrap.c -python ${top_srcdir}/src/mytest.i
        
mytest.py: mytest_wrap.c

clean-local:
	rm -rf mytest_wrap.c mytest.py mytest.pyc
        
endif