cpython/Doc/extending/building.rst

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.. highlightlang:: c
.. _building:
********************************************
Building C and C++ Extensions with distutils
********************************************
.. sectionauthor:: Martin v. Löwis <martin@v.loewis.de>
Starting in Python 1.4, Python provides, on Unix, a special make file for
building make files for building dynamically-linked extensions and custom
interpreters. Starting with Python 2.0, this mechanism (known as related to
Makefile.pre.in, and Setup files) is no longer supported. Building custom
interpreters was rarely used, and extension modules can be built using
distutils.
Building an extension module using distutils requires that distutils is
installed on the build machine, which is included in Python 2.x and available
separately for Python 1.5. Since distutils also supports creation of binary
packages, users don't necessarily need a compiler and distutils to install the
extension.
A distutils package contains a driver script, :file:`setup.py`. This is a plain
Python file, which, in the most simple case, could look like this::
from distutils.core import setup, Extension
module1 = Extension('demo',
sources = ['demo.c'])
setup (name = 'PackageName',
version = '1.0',
description = 'This is a demo package',
ext_modules = [module1])
With this :file:`setup.py`, and a file :file:`demo.c`, running ::
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python setup.py build
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will compile :file:`demo.c`, and produce an extension module named ``demo`` in
the :file:`build` directory. Depending on the system, the module file will end
up in a subdirectory :file:`build/lib.system`, and may have a name like
:file:`demo.so` or :file:`demo.pyd`.
In the :file:`setup.py`, all execution is performed by calling the ``setup``
function. This takes a variable number of keyword arguments, of which the
example above uses only a subset. Specifically, the example specifies
meta-information to build packages, and it specifies the contents of the
package. Normally, a package will contain of addition modules, like Python
source modules, documentation, subpackages, etc. Please refer to the distutils
documentation in :ref:`distutils-index` to learn more about the features of
distutils; this section explains building extension modules only.
It is common to pre-compute arguments to :func:`setup`, to better structure the
driver script. In the example above, the\ ``ext_modules`` argument to
:func:`setup` is a list of extension modules, each of which is an instance of
the :class:`Extension`. In the example, the instance defines an extension named
``demo`` which is build by compiling a single source file, :file:`demo.c`.
In many cases, building an extension is more complex, since additional
preprocessor defines and libraries may be needed. This is demonstrated in the
example below. ::
from distutils.core import setup, Extension
module1 = Extension('demo',
define_macros = [('MAJOR_VERSION', '1'),
('MINOR_VERSION', '0')],
include_dirs = ['/usr/local/include'],
libraries = ['tcl83'],
library_dirs = ['/usr/local/lib'],
sources = ['demo.c'])
setup (name = 'PackageName',
version = '1.0',
description = 'This is a demo package',
author = 'Martin v. Loewis',
author_email = 'martin@v.loewis.de',
Merged revisions 60151-60159,60161-60168,60170,60172-60173,60175 via svnmerge from svn+ssh://pythondev@svn.python.org/python/trunk ........ r60151 | christian.heimes | 2008-01-21 14:11:15 +0100 (Mon, 21 Jan 2008) | 1 line A bunch of header files were not listed as dependencies for object files. Changes to files like Parser/parser.h weren't picked up by make. ........ r60152 | georg.brandl | 2008-01-21 15:16:46 +0100 (Mon, 21 Jan 2008) | 3 lines #1087741: make mmap.mmap the type of mmap objects, not a factory function. Allow it to be subclassed. ........ r60153 | georg.brandl | 2008-01-21 15:18:14 +0100 (Mon, 21 Jan 2008) | 2 lines mmap is an extension module. ........ r60154 | georg.brandl | 2008-01-21 17:28:13 +0100 (Mon, 21 Jan 2008) | 2 lines Fix example. ........ r60155 | georg.brandl | 2008-01-21 17:34:07 +0100 (Mon, 21 Jan 2008) | 2 lines #1555501: document plistlib and move it to the general library. ........ r60156 | georg.brandl | 2008-01-21 17:36:00 +0100 (Mon, 21 Jan 2008) | 2 lines Add a stub for bundlebuilder documentation. ........ r60157 | georg.brandl | 2008-01-21 17:46:58 +0100 (Mon, 21 Jan 2008) | 2 lines Removing bundlebuilder docs again -- it's not to be used anymore (see #779825). ........ r60158 | georg.brandl | 2008-01-21 17:51:51 +0100 (Mon, 21 Jan 2008) | 2 lines #997912: acknowledge nested scopes in tutorial. ........ r60159 | vinay.sajip | 2008-01-21 18:02:26 +0100 (Mon, 21 Jan 2008) | 1 line Fix: #1836: Off-by-one bug in TimedRotatingFileHandler rollover calculation. Patch thanks to Kathryn M. Kowalski. ........ r60161 | georg.brandl | 2008-01-21 18:13:03 +0100 (Mon, 21 Jan 2008) | 2 lines Adapt pydoc to new doc URLs. ........ r60162 | georg.brandl | 2008-01-21 18:17:00 +0100 (Mon, 21 Jan 2008) | 2 lines Fix old link. ........ r60163 | georg.brandl | 2008-01-21 18:22:06 +0100 (Mon, 21 Jan 2008) | 2 lines #1726198: replace while 1: fp.readline() with file iteration. ........ r60164 | georg.brandl | 2008-01-21 18:29:23 +0100 (Mon, 21 Jan 2008) | 2 lines Clarify $ behavior in re docstring. #1631394. ........ r60165 | vinay.sajip | 2008-01-21 18:39:22 +0100 (Mon, 21 Jan 2008) | 1 line Minor documentation change - hyperlink tidied up. ........ r60166 | georg.brandl | 2008-01-21 18:42:40 +0100 (Mon, 21 Jan 2008) | 2 lines #1530959: change distutils build dir for --with-pydebug python builds. ........ r60167 | vinay.sajip | 2008-01-21 19:16:05 +0100 (Mon, 21 Jan 2008) | 1 line Updated to include news on recent logging fixes and documentation changes. ........ r60168 | georg.brandl | 2008-01-21 19:35:49 +0100 (Mon, 21 Jan 2008) | 3 lines Issue #1882: when compiling code from a string, encoding cookies in the second line of code were not always recognized correctly. ........ r60170 | georg.brandl | 2008-01-21 19:36:51 +0100 (Mon, 21 Jan 2008) | 2 lines Add NEWS entry for #1882. ........ r60172 | georg.brandl | 2008-01-21 19:41:24 +0100 (Mon, 21 Jan 2008) | 2 lines Use original location of document, which has translations. ........ r60173 | walter.doerwald | 2008-01-21 21:18:04 +0100 (Mon, 21 Jan 2008) | 2 lines Follow PEP 8 in module docstring. ........ r60175 | georg.brandl | 2008-01-21 21:20:53 +0100 (Mon, 21 Jan 2008) | 2 lines Adapt to latest doctools refactoring. ........
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url = 'http://docs.python.org/extending/building',
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long_description = '''
This is really just a demo package.
''',
ext_modules = [module1])
In this example, :func:`setup` is called with additional meta-information, which
is recommended when distribution packages have to be built. For the extension
itself, it specifies preprocessor defines, include directories, library
directories, and libraries. Depending on the compiler, distutils passes this
information in different ways to the compiler. For example, on Unix, this may
result in the compilation commands ::
gcc -DNDEBUG -g -O3 -Wall -Wstrict-prototypes -fPIC -DMAJOR_VERSION=1 -DMINOR_VERSION=0 -I/usr/local/include -I/usr/local/include/python2.2 -c demo.c -o build/temp.linux-i686-2.2/demo.o
gcc -shared build/temp.linux-i686-2.2/demo.o -L/usr/local/lib -ltcl83 -o build/lib.linux-i686-2.2/demo.so
These lines are for demonstration purposes only; distutils users should trust
that distutils gets the invocations right.
.. _distributing:
Distributing your extension modules
===================================
When an extension has been successfully build, there are three ways to use it.
End-users will typically want to install the module, they do so by running ::
python setup.py install
Module maintainers should produce source packages; to do so, they run ::
python setup.py sdist
In some cases, additional files need to be included in a source distribution;
this is done through a :file:`MANIFEST.in` file; see the distutils documentation
for details.
If the source distribution has been build successfully, maintainers can also
create binary distributions. Depending on the platform, one of the following
commands can be used to do so. ::
python setup.py bdist_wininst
python setup.py bdist_rpm
python setup.py bdist_dumb