--- /dev/null
- instructions (although it's always a good idea to do so anyways).
+.. highlightlang:: none
+
+.. _install-index:
+
+*****************************
+ Installing Python Modules
+*****************************
+
+:Author: Greg Ward
+:Release: |version|
+:Date: |today|
+
+.. TODO: Fill in XXX comments
+
+.. The audience for this document includes people who don't know anything
+ about Python and aren't about to learn the language just in order to
+ install and maintain it for their users, i.e. system administrators.
+ Thus, I have to be sure to explain the basics at some point:
+ sys.path and PYTHONPATH at least. Should probably give pointers to
+ other docs on "import site", PYTHONSTARTUP, PYTHONHOME, etc.
+
+ Finally, it might be useful to include all the material from my "Care
+ and Feeding of a Python Installation" talk in here somewhere. Yow!
+
+.. topic:: Abstract
+
+ This document describes the Python Distribution Utilities ("Distutils") from the
+ end-user's point-of-view, describing how to extend the capabilities of a
+ standard Python installation by building and installing third-party Python
+ modules and extensions.
+
+
+.. _inst-intro:
+
+Introduction
+============
+
+Although Python's extensive standard library covers many programming needs,
+there often comes a time when you need to add some new functionality to your
+Python installation in the form of third-party modules. This might be necessary
+to support your own programming, or to support an application that you want to
+use and that happens to be written in Python.
+
+In the past, there has been little support for adding third-party modules to an
+existing Python installation. With the introduction of the Python Distribution
+Utilities (Distutils for short) in Python 2.0, this changed.
+
+This document is aimed primarily at the people who need to install third-party
+Python modules: end-users and system administrators who just need to get some
+Python application running, and existing Python programmers who want to add some
+new goodies to their toolbox. You don't need to know Python to read this
+document; there will be some brief forays into using Python's interactive mode
+to explore your installation, but that's it. If you're looking for information
+on how to distribute your own Python modules so that others may use them, see
+the :ref:`distutils-index` manual.
+
+
+.. _inst-trivial-install:
+
+Best case: trivial installation
+-------------------------------
+
+In the best case, someone will have prepared a special version of the module
+distribution you want to install that is targeted specifically at your platform
+and is installed just like any other software on your platform. For example,
+the module developer might make an executable installer available for Windows
+users, an RPM package for users of RPM-based Linux systems (Red Hat, SuSE,
+Mandrake, and many others), a Debian package for users of Debian-based Linux
+systems, and so forth.
+
+In that case, you would download the installer appropriate to your platform and
+do the obvious thing with it: run it if it's an executable installer, ``rpm
+--install`` it if it's an RPM, etc. You don't need to run Python or a setup
+script, you don't need to compile anything---you might not even need to read any
++instructions (although it's always a good idea to do so anyway).
+
+Of course, things will not always be that easy. You might be interested in a
+module distribution that doesn't have an easy-to-use installer for your
+platform. In that case, you'll have to start with the source distribution
+released by the module's author/maintainer. Installing from a source
+distribution is not too hard, as long as the modules are packaged in the
+standard way. The bulk of this document is about building and installing
+modules from standard source distributions.
+
+
+.. _inst-new-standard:
+
+The new standard: Distutils
+---------------------------
+
+If you download a module source distribution, you can tell pretty quickly if it
+was packaged and distributed in the standard way, i.e. using the Distutils.
+First, the distribution's name and version number will be featured prominently
+in the name of the downloaded archive, e.g. :file:`foo-1.0.tar.gz` or
+:file:`widget-0.9.7.zip`. Next, the archive will unpack into a similarly-named
+directory: :file:`foo-1.0` or :file:`widget-0.9.7`. Additionally, the
+distribution will contain a setup script :file:`setup.py`, and a file named
+:file:`README.txt` or possibly just :file:`README`, which should explain that
+building and installing the module distribution is a simple matter of running
+one command from a terminal::
+
+ python setup.py install
+
+For Windows, this command should be run from a command prompt windows ("DOS
+box")::
+
+ setup.py install
+
+If all these things are true, then you already know how to build and install the
+modules you've just downloaded: Run the command above. Unless you need to
+install things in a non-standard way or customize the build process, you don't
+really need this manual. Or rather, the above command is everything you need to
+get out of this manual.
+
+
+.. _inst-standard-install:
+
+Standard Build and Install
+==========================
+
+As described in section :ref:`inst-new-standard`, building and installing a module
+distribution using the Distutils is usually one simple command to run from a
+terminal::
+
+ python setup.py install
+
+
+.. _inst-platform-variations:
+
+Platform variations
+-------------------
+
+You should always run the setup command from the distribution root directory,
+i.e. the top-level subdirectory that the module source distribution unpacks
+into. For example, if you've just downloaded a module source distribution
+:file:`foo-1.0.tar.gz` onto a Unix system, the normal thing to do is::
+
+ gunzip -c foo-1.0.tar.gz | tar xf - # unpacks into directory foo-1.0
+ cd foo-1.0
+ python setup.py install
+
+On Windows, you'd probably download :file:`foo-1.0.zip`. If you downloaded the
+archive file to :file:`C:\\Temp`, then it would unpack into
+:file:`C:\\Temp\\foo-1.0`; you can use either a archive manipulator with a
+graphical user interface (such as WinZip) or a command-line tool (such as
+:program:`unzip` or :program:`pkunzip`) to unpack the archive. Then, open a
+command prompt window ("DOS box"), and run::
+
+ cd c:\Temp\foo-1.0
+ python setup.py install
+
+
+.. _inst-splitting-up:
+
+Splitting the job up
+--------------------
+
+Running ``setup.py install`` builds and installs all modules in one run. If you
+prefer to work incrementally---especially useful if you want to customize the
+build process, or if things are going wrong---you can use the setup script to do
+one thing at a time. This is particularly helpful when the build and install
+will be done by different users---for example, you might want to build a module
+distribution and hand it off to a system administrator for installation (or do
+it yourself, with super-user privileges).
+
+For example, you can build everything in one step, and then install everything
+in a second step, by invoking the setup script twice::
+
+ python setup.py build
+ python setup.py install
+
+If you do this, you will notice that running the :command:`install` command
+first runs the :command:`build` command, which---in this case---quickly notices
+that it has nothing to do, since everything in the :file:`build` directory is
+up-to-date.
+
+You may not need this ability to break things down often if all you do is
+install modules downloaded off the 'net, but it's very handy for more advanced
+tasks. If you get into distributing your own Python modules and extensions,
+you'll run lots of individual Distutils commands on their own.
+
+
+.. _inst-how-build-works:
+
+How building works
+------------------
+
+As implied above, the :command:`build` command is responsible for putting the
+files to install into a *build directory*. By default, this is :file:`build`
+under the distribution root; if you're excessively concerned with speed, or want
+to keep the source tree pristine, you can change the build directory with the
+:option:`--build-base` option. For example::
+
+ python setup.py build --build-base=/tmp/pybuild/foo-1.0
+
+(Or you could do this permanently with a directive in your system or personal
+Distutils configuration file; see section :ref:`inst-config-files`.) Normally, this
+isn't necessary.
+
+The default layout for the build tree is as follows::
+
+ --- build/ --- lib/
+ or
+ --- build/ --- lib.<plat>/
+ temp.<plat>/
+
+where ``<plat>`` expands to a brief description of the current OS/hardware
+platform and Python version. The first form, with just a :file:`lib` directory,
+is used for "pure module distributions"---that is, module distributions that
+include only pure Python modules. If a module distribution contains any
+extensions (modules written in C/C++), then the second form, with two ``<plat>``
+directories, is used. In that case, the :file:`temp.{plat}` directory holds
+temporary files generated by the compile/link process that don't actually get
+installed. In either case, the :file:`lib` (or :file:`lib.{plat}`) directory
+contains all Python modules (pure Python and extensions) that will be installed.
+
+In the future, more directories will be added to handle Python scripts,
+documentation, binary executables, and whatever else is needed to handle the job
+of installing Python modules and applications.
+
+
+.. _inst-how-install-works:
+
+How installation works
+----------------------
+
+After the :command:`build` command runs (whether you run it explicitly, or the
+:command:`install` command does it for you), the work of the :command:`install`
+command is relatively simple: all it has to do is copy everything under
+:file:`build/lib` (or :file:`build/lib.{plat}`) to your chosen installation
+directory.
+
+If you don't choose an installation directory---i.e., if you just run ``setup.py
+install``\ ---then the :command:`install` command installs to the standard
+location for third-party Python modules. This location varies by platform and
+by how you built/installed Python itself. On Unix (and Mac OS X, which is also
+Unix-based), it also depends on whether the module distribution being installed
+is pure Python or contains extensions ("non-pure"):
+
++-----------------+-----------------------------------------------------+--------------------------------------------------+-------+
+| Platform | Standard installation location | Default value | Notes |
++=================+=====================================================+==================================================+=======+
+| Unix (pure) | :file:`{prefix}/lib/python{X.Y}/site-packages` | :file:`/usr/local/lib/python{X.Y}/site-packages` | \(1) |
++-----------------+-----------------------------------------------------+--------------------------------------------------+-------+
+| Unix (non-pure) | :file:`{exec-prefix}/lib/python{X.Y}/site-packages` | :file:`/usr/local/lib/python{X.Y}/site-packages` | \(1) |
++-----------------+-----------------------------------------------------+--------------------------------------------------+-------+
+| Windows | :file:`{prefix}\\Lib\\site-packages` | :file:`C:\\Python{XY}\\Lib\\site-packages` | \(2) |
++-----------------+-----------------------------------------------------+--------------------------------------------------+-------+
+
+Notes:
+
+(1)
+ Most Linux distributions include Python as a standard part of the system, so
+ :file:`{prefix}` and :file:`{exec-prefix}` are usually both :file:`/usr` on
+ Linux. If you build Python yourself on Linux (or any Unix-like system), the
+ default :file:`{prefix}` and :file:`{exec-prefix}` are :file:`/usr/local`.
+
+(2)
+ The default installation directory on Windows was :file:`C:\\Program
+ Files\\Python` under Python 1.6a1, 1.5.2, and earlier.
+
+:file:`{prefix}` and :file:`{exec-prefix}` stand for the directories that Python
+is installed to, and where it finds its libraries at run-time. They are always
+the same under Windows, and very often the same under Unix and Mac OS X. You
+can find out what your Python installation uses for :file:`{prefix}` and
+:file:`{exec-prefix}` by running Python in interactive mode and typing a few
+simple commands. Under Unix, just type ``python`` at the shell prompt. Under
+Windows, choose :menuselection:`Start --> Programs --> Python X.Y -->
+Python (command line)`. Once the interpreter is started, you type Python code
+at the prompt. For example, on my Linux system, I type the three Python
+statements shown below, and get the output as shown, to find out my
+:file:`{prefix}` and :file:`{exec-prefix}`::
+
+ Python 2.4 (#26, Aug 7 2004, 17:19:02)
+ Type "help", "copyright", "credits" or "license" for more information.
+ >>> import sys
+ >>> sys.prefix
+ '/usr'
+ >>> sys.exec_prefix
+ '/usr'
+
+If you don't want to install modules to the standard location, or if you don't
+have permission to write there, then you need to read about alternate
+installations in section :ref:`inst-alt-install`. If you want to customize your
+installation directories more heavily, see section :ref:`inst-custom-install` on
+custom installations.
+
+
+.. _inst-alt-install:
+
+Alternate Installation
+======================
+
+Often, it is necessary or desirable to install modules to a location other than
+the standard location for third-party Python modules. For example, on a Unix
+system you might not have permission to write to the standard third-party module
+directory. Or you might wish to try out a module before making it a standard
+part of your local Python installation. This is especially true when upgrading
+a distribution already present: you want to make sure your existing base of
+scripts still works with the new version before actually upgrading.
+
+The Distutils :command:`install` command is designed to make installing module
+distributions to an alternate location simple and painless. The basic idea is
+that you supply a base directory for the installation, and the
+:command:`install` command picks a set of directories (called an *installation
+scheme*) under this base directory in which to install files. The details
+differ across platforms, so read whichever of the following sections applies to
+you.
+
+
+.. _inst-alt-install-prefix:
+
+Alternate installation: the home scheme
+---------------------------------------
+
+The idea behind the "home scheme" is that you build and maintain a personal
+stash of Python modules. This scheme's name is derived from the idea of a
+"home" directory on Unix, since it's not unusual for a Unix user to make their
+home directory have a layout similar to :file:`/usr/` or :file:`/usr/local/`.
+This scheme can be used by anyone, regardless of the operating system they
+are installing for.
+
+Installing a new module distribution is as simple as ::
+
+ python setup.py install --home=<dir>
+
+where you can supply any directory you like for the :option:`--home` option. On
+Unix, lazy typists can just type a tilde (``~``); the :command:`install` command
+will expand this to your home directory::
+
+ python setup.py install --home=~
+
+The :option:`--home` option defines the installation base directory. Files are
+installed to the following directories under the installation base as follows:
+
++------------------------------+---------------------------+-----------------------------+
+| Type of file | Installation Directory | Override option |
++==============================+===========================+=============================+
+| pure module distribution | :file:`{home}/lib/python` | :option:`--install-purelib` |
++------------------------------+---------------------------+-----------------------------+
+| non-pure module distribution | :file:`{home}/lib/python` | :option:`--install-platlib` |
++------------------------------+---------------------------+-----------------------------+
+| scripts | :file:`{home}/bin` | :option:`--install-scripts` |
++------------------------------+---------------------------+-----------------------------+
+| data | :file:`{home}/share` | :option:`--install-data` |
++------------------------------+---------------------------+-----------------------------+
+
+
+.. _inst-alt-install-home:
+
+Alternate installation: Unix (the prefix scheme)
+------------------------------------------------
+
+The "prefix scheme" is useful when you wish to use one Python installation to
+perform the build/install (i.e., to run the setup script), but install modules
+into the third-party module directory of a different Python installation (or
+something that looks like a different Python installation). If this sounds a
+trifle unusual, it is---that's why the "home scheme" comes first. However,
+there are at least two known cases where the prefix scheme will be useful.
+
+First, consider that many Linux distributions put Python in :file:`/usr`, rather
+than the more traditional :file:`/usr/local`. This is entirely appropriate,
+since in those cases Python is part of "the system" rather than a local add-on.
+However, if you are installing Python modules from source, you probably want
+them to go in :file:`/usr/local/lib/python2.{X}` rather than
+:file:`/usr/lib/python2.{X}`. This can be done with ::
+
+ /usr/bin/python setup.py install --prefix=/usr/local
+
+Another possibility is a network filesystem where the name used to write to a
+remote directory is different from the name used to read it: for example, the
+Python interpreter accessed as :file:`/usr/local/bin/python` might search for
+modules in :file:`/usr/local/lib/python2.{X}`, but those modules would have to
+be installed to, say, :file:`/mnt/{@server}/export/lib/python2.{X}`. This could
+be done with ::
+
+ /usr/local/bin/python setup.py install --prefix=/mnt/@server/export
+
+In either case, the :option:`--prefix` option defines the installation base, and
+the :option:`--exec-prefix` option defines the platform-specific installation
+base, which is used for platform-specific files. (Currently, this just means
+non-pure module distributions, but could be expanded to C libraries, binary
+executables, etc.) If :option:`--exec-prefix` is not supplied, it defaults to
+:option:`--prefix`. Files are installed as follows:
+
++------------------------------+-----------------------------------------------------+-----------------------------+
+| Type of file | Installation Directory | Override option |
++==============================+=====================================================+=============================+
+| pure module distribution | :file:`{prefix}/lib/python{X.Y}/site-packages` | :option:`--install-purelib` |
++------------------------------+-----------------------------------------------------+-----------------------------+
+| non-pure module distribution | :file:`{exec-prefix}/lib/python{X.Y}/site-packages` | :option:`--install-platlib` |
++------------------------------+-----------------------------------------------------+-----------------------------+
+| scripts | :file:`{prefix}/bin` | :option:`--install-scripts` |
++------------------------------+-----------------------------------------------------+-----------------------------+
+| data | :file:`{prefix}/share` | :option:`--install-data` |
++------------------------------+-----------------------------------------------------+-----------------------------+
+
+There is no requirement that :option:`--prefix` or :option:`--exec-prefix`
+actually point to an alternate Python installation; if the directories listed
+above do not already exist, they are created at installation time.
+
+Incidentally, the real reason the prefix scheme is important is simply that a
+standard Unix installation uses the prefix scheme, but with :option:`--prefix`
+and :option:`--exec-prefix` supplied by Python itself as ``sys.prefix`` and
+``sys.exec_prefix``. Thus, you might think you'll never use the prefix scheme,
+but every time you run ``python setup.py install`` without any other options,
+you're using it.
+
+Note that installing extensions to an alternate Python installation has no
+effect on how those extensions are built: in particular, the Python header files
+(:file:`Python.h` and friends) installed with the Python interpreter used to run
+the setup script will be used in compiling extensions. It is your
+responsibility to ensure that the interpreter used to run extensions installed
+in this way is compatible with the interpreter used to build them. The best way
+to do this is to ensure that the two interpreters are the same version of Python
+(possibly different builds, or possibly copies of the same build). (Of course,
+if your :option:`--prefix` and :option:`--exec-prefix` don't even point to an
+alternate Python installation, this is immaterial.)
+
+
+.. _inst-alt-install-windows:
+
+Alternate installation: Windows (the prefix scheme)
+---------------------------------------------------
+
+Windows has no concept of a user's home directory, and since the standard Python
+installation under Windows is simpler than under Unix, the :option:`--prefix`
+option has traditionally been used to install additional packages in separate
+locations on Windows. ::
+
+ python setup.py install --prefix="\Temp\Python"
+
+to install modules to the :file:`\\Temp\\Python` directory on the current drive.
+
+The installation base is defined by the :option:`--prefix` option; the
+:option:`--exec-prefix` option is not supported under Windows. Files are
+installed as follows:
+
++------------------------------+---------------------------+-----------------------------+
+| Type of file | Installation Directory | Override option |
++==============================+===========================+=============================+
+| pure module distribution | :file:`{prefix}` | :option:`--install-purelib` |
++------------------------------+---------------------------+-----------------------------+
+| non-pure module distribution | :file:`{prefix}` | :option:`--install-platlib` |
++------------------------------+---------------------------+-----------------------------+
+| scripts | :file:`{prefix}\\Scripts` | :option:`--install-scripts` |
++------------------------------+---------------------------+-----------------------------+
+| data | :file:`{prefix}\\Data` | :option:`--install-data` |
++------------------------------+---------------------------+-----------------------------+
+
+
+.. _inst-custom-install:
+
+Custom Installation
+===================
+
+Sometimes, the alternate installation schemes described in section
+:ref:`inst-alt-install` just don't do what you want. You might want to tweak just
+one or two directories while keeping everything under the same base directory,
+or you might want to completely redefine the installation scheme. In either
+case, you're creating a *custom installation scheme*.
+
+You probably noticed the column of "override options" in the tables describing
+the alternate installation schemes above. Those options are how you define a
+custom installation scheme. These override options can be relative, absolute,
+or explicitly defined in terms of one of the installation base directories.
+(There are two installation base directories, and they are normally the same---
+they only differ when you use the Unix "prefix scheme" and supply different
+:option:`--prefix` and :option:`--exec-prefix` options.)
+
+For example, say you're installing a module distribution to your home directory
+under Unix---but you want scripts to go in :file:`~/scripts` rather than
+:file:`~/bin`. As you might expect, you can override this directory with the
+:option:`--install-scripts` option; in this case, it makes most sense to supply
+a relative path, which will be interpreted relative to the installation base
+directory (your home directory, in this case)::
+
+ python setup.py install --home=~ --install-scripts=scripts
+
+Another Unix example: suppose your Python installation was built and installed
+with a prefix of :file:`/usr/local/python`, so under a standard installation
+scripts will wind up in :file:`/usr/local/python/bin`. If you want them in
+:file:`/usr/local/bin` instead, you would supply this absolute directory for the
+:option:`--install-scripts` option::
+
+ python setup.py install --install-scripts=/usr/local/bin
+
+(This performs an installation using the "prefix scheme," where the prefix is
+whatever your Python interpreter was installed with--- :file:`/usr/local/python`
+in this case.)
+
+If you maintain Python on Windows, you might want third-party modules to live in
+a subdirectory of :file:`{prefix}`, rather than right in :file:`{prefix}`
+itself. This is almost as easy as customizing the script installation directory
+---you just have to remember that there are two types of modules to worry about,
+pure modules and non-pure modules (i.e., modules from a non-pure distribution).
+For example::
+
+ python setup.py install --install-purelib=Site --install-platlib=Site
+
+The specified installation directories are relative to :file:`{prefix}`. Of
+course, you also have to ensure that these directories are in Python's module
+search path, such as by putting a :file:`.pth` file in :file:`{prefix}`. See
+section :ref:`inst-search-path` to find out how to modify Python's search path.
+
+If you want to define an entire installation scheme, you just have to supply all
+of the installation directory options. The recommended way to do this is to
+supply relative paths; for example, if you want to maintain all Python
+module-related files under :file:`python` in your home directory, and you want a
+separate directory for each platform that you use your home directory from, you
+might define the following installation scheme::
+
+ python setup.py install --home=~ \
+ --install-purelib=python/lib \
+ --install-platlib=python/lib.$PLAT \
+ --install-scripts=python/scripts
+ --install-data=python/data
+
+or, equivalently, ::
+
+ python setup.py install --home=~/python \
+ --install-purelib=lib \
+ --install-platlib='lib.$PLAT' \
+ --install-scripts=scripts
+ --install-data=data
+
+``$PLAT`` is not (necessarily) an environment variable---it will be expanded by
+the Distutils as it parses your command line options, just as it does when
+parsing your configuration file(s).
+
+Obviously, specifying the entire installation scheme every time you install a
+new module distribution would be very tedious. Thus, you can put these options
+into your Distutils config file (see section :ref:`inst-config-files`)::
+
+ [install]
+ install-base=$HOME
+ install-purelib=python/lib
+ install-platlib=python/lib.$PLAT
+ install-scripts=python/scripts
+ install-data=python/data
+
+or, equivalently, ::
+
+ [install]
+ install-base=$HOME/python
+ install-purelib=lib
+ install-platlib=lib.$PLAT
+ install-scripts=scripts
+ install-data=data
+
+Note that these two are *not* equivalent if you supply a different installation
+base directory when you run the setup script. For example, ::
+
+ python setup.py install --install-base=/tmp
+
+would install pure modules to :file:`{/tmp/python/lib}` in the first case, and
+to :file:`{/tmp/lib}` in the second case. (For the second case, you probably
+want to supply an installation base of :file:`/tmp/python`.)
+
+You probably noticed the use of ``$HOME`` and ``$PLAT`` in the sample
+configuration file input. These are Distutils configuration variables, which
+bear a strong resemblance to environment variables. In fact, you can use
+environment variables in config files on platforms that have such a notion but
+the Distutils additionally define a few extra variables that may not be in your
+environment, such as ``$PLAT``. (And of course, on systems that don't have
+environment variables, such as Mac OS 9, the configuration variables supplied by
+the Distutils are the only ones you can use.) See section :ref:`inst-config-files`
+for details.
+
+.. XXX need some Windows examples---when would custom installation schemes be
+ needed on those platforms?
+
+
+.. XXX I'm not sure where this section should go.
+
+.. _inst-search-path:
+
+Modifying Python's Search Path
+------------------------------
+
+When the Python interpreter executes an :keyword:`import` statement, it searches
+for both Python code and extension modules along a search path. A default value
+for the path is configured into the Python binary when the interpreter is built.
+You can determine the path by importing the :mod:`sys` module and printing the
+value of ``sys.path``. ::
+
+ $ python
+ Python 2.2 (#11, Oct 3 2002, 13:31:27)
+ [GCC 2.96 20000731 (Red Hat Linux 7.3 2.96-112)] on linux2
+ Type "help", "copyright", "credits" or "license" for more information.
+ >>> import sys
+ >>> sys.path
+ ['', '/usr/local/lib/python2.3', '/usr/local/lib/python2.3/plat-linux2',
+ '/usr/local/lib/python2.3/lib-tk', '/usr/local/lib/python2.3/lib-dynload',
+ '/usr/local/lib/python2.3/site-packages']
+ >>>
+
+The null string in ``sys.path`` represents the current working directory.
+
+The expected convention for locally installed packages is to put them in the
+:file:`{...}/site-packages/` directory, but you may want to install Python
+modules into some arbitrary directory. For example, your site may have a
+convention of keeping all software related to the web server under :file:`/www`.
+Add-on Python modules might then belong in :file:`/www/python`, and in order to
+import them, this directory must be added to ``sys.path``. There are several
+different ways to add the directory.
+
+The most convenient way is to add a path configuration file to a directory
+that's already on Python's path, usually to the :file:`.../site-packages/`
+directory. Path configuration files have an extension of :file:`.pth`, and each
+line must contain a single path that will be appended to ``sys.path``. (Because
+the new paths are appended to ``sys.path``, modules in the added directories
+will not override standard modules. This means you can't use this mechanism for
+installing fixed versions of standard modules.)
+
+Paths can be absolute or relative, in which case they're relative to the
+directory containing the :file:`.pth` file. See the documentation of
+the :mod:`site` module for more information.
+
+A slightly less convenient way is to edit the :file:`site.py` file in Python's
+standard library, and modify ``sys.path``. :file:`site.py` is automatically
+imported when the Python interpreter is executed, unless the :option:`-S` switch
+is supplied to suppress this behaviour. So you could simply edit
+:file:`site.py` and add two lines to it::
+
+ import sys
+ sys.path.append('/www/python/')
+
+However, if you reinstall the same major version of Python (perhaps when
+upgrading from 2.2 to 2.2.2, for example) :file:`site.py` will be overwritten by
+the stock version. You'd have to remember that it was modified and save a copy
+before doing the installation.
+
+There are two environment variables that can modify ``sys.path``.
+:envvar:`PYTHONHOME` sets an alternate value for the prefix of the Python
+installation. For example, if :envvar:`PYTHONHOME` is set to ``/www/python``,
+the search path will be set to ``['', '/www/python/lib/pythonX.Y/',
+'/www/python/lib/pythonX.Y/plat-linux2', ...]``.
+
+The :envvar:`PYTHONPATH` variable can be set to a list of paths that will be
+added to the beginning of ``sys.path``. For example, if :envvar:`PYTHONPATH` is
+set to ``/www/python:/opt/py``, the search path will begin with
+``['/www/python', '/opt/py']``. (Note that directories must exist in order to
+be added to ``sys.path``; the :mod:`site` module removes paths that don't
+exist.)
+
+Finally, ``sys.path`` is just a regular Python list, so any Python application
+can modify it by adding or removing entries.
+
+
+.. _inst-config-files:
+
+Distutils Configuration Files
+=============================
+
+As mentioned above, you can use Distutils configuration files to record personal
+or site preferences for any Distutils options. That is, any option to any
+command can be stored in one of two or three (depending on your platform)
+configuration files, which will be consulted before the command-line is parsed.
+This means that configuration files will override default values, and the
+command-line will in turn override configuration files. Furthermore, if
+multiple configuration files apply, values from "earlier" files are overridden
+by "later" files.
+
+
+.. _inst-config-filenames:
+
+Location and names of config files
+----------------------------------
+
+The names and locations of the configuration files vary slightly across
+platforms. On Unix and Mac OS X, the three configuration files (in the order
+they are processed) are:
+
++--------------+----------------------------------------------------------+-------+
+| Type of file | Location and filename | Notes |
++==============+==========================================================+=======+
+| system | :file:`{prefix}/lib/python{ver}/distutils/distutils.cfg` | \(1) |
++--------------+----------------------------------------------------------+-------+
+| personal | :file:`$HOME/.pydistutils.cfg` | \(2) |
++--------------+----------------------------------------------------------+-------+
+| local | :file:`setup.cfg` | \(3) |
++--------------+----------------------------------------------------------+-------+
+
+And on Windows, the configuration files are:
+
++--------------+-------------------------------------------------+-------+
+| Type of file | Location and filename | Notes |
++==============+=================================================+=======+
+| system | :file:`{prefix}\\Lib\\distutils\\distutils.cfg` | \(4) |
++--------------+-------------------------------------------------+-------+
+| personal | :file:`%HOME%\\pydistutils.cfg` | \(5) |
++--------------+-------------------------------------------------+-------+
+| local | :file:`setup.cfg` | \(3) |
++--------------+-------------------------------------------------+-------+
+
+On all platforms, the "personal" file can be temporarily disabled by
+passing the `--no-user-cfg` option.
+
+Notes:
+
+(1)
+ Strictly speaking, the system-wide configuration file lives in the directory
+ where the Distutils are installed; under Python 1.6 and later on Unix, this is
+ as shown. For Python 1.5.2, the Distutils will normally be installed to
+ :file:`{prefix}/lib/python1.5/site-packages/distutils`, so the system
+ configuration file should be put there under Python 1.5.2.
+
+(2)
+ On Unix, if the :envvar:`HOME` environment variable is not defined, the user's
+ home directory will be determined with the :func:`getpwuid` function from the
+ standard :mod:`pwd` module. This is done by the :func:`os.path.expanduser`
+ function used by Distutils.
+
+(3)
+ I.e., in the current directory (usually the location of the setup script).
+
+(4)
+ (See also note (1).) Under Python 1.6 and later, Python's default "installation
+ prefix" is :file:`C:\\Python`, so the system configuration file is normally
+ :file:`C:\\Python\\Lib\\distutils\\distutils.cfg`. Under Python 1.5.2, the
+ default prefix was :file:`C:\\Program Files\\Python`, and the Distutils were not
+ part of the standard library---so the system configuration file would be
+ :file:`C:\\Program Files\\Python\\distutils\\distutils.cfg` in a standard Python
+ 1.5.2 installation under Windows.
+
+(5)
+ On Windows, if the :envvar:`HOME` environment variable is not defined,
+ :envvar:`USERPROFILE` then :envvar:`HOMEDRIVE` and :envvar:`HOMEPATH` will
+ be tried. This is done by the :func:`os.path.expanduser` function used
+ by Distutils.
+
+
+.. _inst-config-syntax:
+
+Syntax of config files
+----------------------
+
+The Distutils configuration files all have the same syntax. The config files
+are grouped into sections. There is one section for each Distutils command,
+plus a ``global`` section for global options that affect every command. Each
+section consists of one option per line, specified as ``option=value``.
+
+For example, the following is a complete config file that just forces all
+commands to run quietly by default::
+
+ [global]
+ verbose=0
+
+If this is installed as the system config file, it will affect all processing of
+any Python module distribution by any user on the current system. If it is
+installed as your personal config file (on systems that support them), it will
+affect only module distributions processed by you. And if it is used as the
+:file:`setup.cfg` for a particular module distribution, it affects only that
+distribution.
+
+You could override the default "build base" directory and make the
+:command:`build\*` commands always forcibly rebuild all files with the
+following::
+
+ [build]
+ build-base=blib
+ force=1
+
+which corresponds to the command-line arguments ::
+
+ python setup.py build --build-base=blib --force
+
+except that including the :command:`build` command on the command-line means
+that command will be run. Including a particular command in config files has no
+such implication; it only means that if the command is run, the options in the
+config file will apply. (Or if other commands that derive values from it are
+run, they will use the values in the config file.)
+
+You can find out the complete list of options for any command using the
+:option:`--help` option, e.g.::
+
+ python setup.py build --help
+
+and you can find out the complete list of global options by using
+:option:`--help` without a command::
+
+ python setup.py --help
+
+See also the "Reference" section of the "Distributing Python Modules" manual.
+
+
+.. _inst-building-ext:
+
+Building Extensions: Tips and Tricks
+====================================
+
+Whenever possible, the Distutils try to use the configuration information made
+available by the Python interpreter used to run the :file:`setup.py` script.
+For example, the same compiler and linker flags used to compile Python will also
+be used for compiling extensions. Usually this will work well, but in
+complicated situations this might be inappropriate. This section discusses how
+to override the usual Distutils behaviour.
+
+
+.. _inst-tweak-flags:
+
+Tweaking compiler/linker flags
+------------------------------
+
+Compiling a Python extension written in C or C++ will sometimes require
+specifying custom flags for the compiler and linker in order to use a particular
+library or produce a special kind of object code. This is especially true if the
+extension hasn't been tested on your platform, or if you're trying to
+cross-compile Python.
+
+In the most general case, the extension author might have foreseen that
+compiling the extensions would be complicated, and provided a :file:`Setup` file
+for you to edit. This will likely only be done if the module distribution
+contains many separate extension modules, or if they often require elaborate
+sets of compiler flags in order to work.
+
+A :file:`Setup` file, if present, is parsed in order to get a list of extensions
+to build. Each line in a :file:`Setup` describes a single module. Lines have
+the following structure::
+
+ module ... [sourcefile ...] [cpparg ...] [library ...]
+
+
+Let's examine each of the fields in turn.
+
+* *module* is the name of the extension module to be built, and should be a
+ valid Python identifier. You can't just change this in order to rename a module
+ (edits to the source code would also be needed), so this should be left alone.
+
+* *sourcefile* is anything that's likely to be a source code file, at least
+ judging by the filename. Filenames ending in :file:`.c` are assumed to be
+ written in C, filenames ending in :file:`.C`, :file:`.cc`, and :file:`.c++` are
+ assumed to be C++, and filenames ending in :file:`.m` or :file:`.mm` are assumed
+ to be in Objective C.
+
+* *cpparg* is an argument for the C preprocessor, and is anything starting with
+ :option:`-I`, :option:`-D`, :option:`-U` or :option:`-C`.
+
+* *library* is anything ending in :file:`.a` or beginning with :option:`-l` or
+ :option:`-L`.
+
+If a particular platform requires a special library on your platform, you can
+add it by editing the :file:`Setup` file and running ``python setup.py build``.
+For example, if the module defined by the line ::
+
+ foo foomodule.c
+
+must be linked with the math library :file:`libm.a` on your platform, simply add
+:option:`-lm` to the line::
+
+ foo foomodule.c -lm
+
+Arbitrary switches intended for the compiler or the linker can be supplied with
+the :option:`-Xcompiler` *arg* and :option:`-Xlinker` *arg* options::
+
+ foo foomodule.c -Xcompiler -o32 -Xlinker -shared -lm
+
+The next option after :option:`-Xcompiler` and :option:`-Xlinker` will be
+appended to the proper command line, so in the above example the compiler will
+be passed the :option:`-o32` option, and the linker will be passed
+:option:`-shared`. If a compiler option requires an argument, you'll have to
+supply multiple :option:`-Xcompiler` options; for example, to pass ``-x c++``
+the :file:`Setup` file would have to contain ``-Xcompiler -x -Xcompiler c++``.
+
+Compiler flags can also be supplied through setting the :envvar:`CFLAGS`
+environment variable. If set, the contents of :envvar:`CFLAGS` will be added to
+the compiler flags specified in the :file:`Setup` file.
+
+
+.. _inst-non-ms-compilers:
+
+Using non-Microsoft compilers on Windows
+----------------------------------------
+
+.. sectionauthor:: Rene Liebscher <R.Liebscher@gmx.de>
+
+
+
+Borland/CodeGear C++
+^^^^^^^^^^^^^^^^^^^^
+
+This subsection describes the necessary steps to use Distutils with the Borland
+C++ compiler version 5.5. First you have to know that Borland's object file
+format (OMF) is different from the format used by the Python version you can
+download from the Python or ActiveState Web site. (Python is built with
+Microsoft Visual C++, which uses COFF as the object file format.) For this
+reason you have to convert Python's library :file:`python25.lib` into the
+Borland format. You can do this as follows:
+
+.. Should we mention that users have to create cfg-files for the compiler?
+.. see also http://community.borland.com/article/0,1410,21205,00.html
+
+::
+
+ coff2omf python25.lib python25_bcpp.lib
+
+The :file:`coff2omf` program comes with the Borland compiler. The file
+:file:`python25.lib` is in the :file:`Libs` directory of your Python
+installation. If your extension uses other libraries (zlib, ...) you have to
+convert them too.
+
+The converted files have to reside in the same directories as the normal
+libraries.
+
+How does Distutils manage to use these libraries with their changed names? If
+the extension needs a library (eg. :file:`foo`) Distutils checks first if it
+finds a library with suffix :file:`_bcpp` (eg. :file:`foo_bcpp.lib`) and then
+uses this library. In the case it doesn't find such a special library it uses
+the default name (:file:`foo.lib`.) [#]_
+
+To let Distutils compile your extension with Borland C++ you now have to type::
+
+ python setup.py build --compiler=bcpp
+
+If you want to use the Borland C++ compiler as the default, you could specify
+this in your personal or system-wide configuration file for Distutils (see
+section :ref:`inst-config-files`.)
+
+
+.. seealso::
+
+ `C++Builder Compiler <http://www.codegear.com/downloads/free/cppbuilder>`_
+ Information about the free C++ compiler from Borland, including links to the
+ download pages.
+
+ `Creating Python Extensions Using Borland's Free Compiler <http://www.cyberus.ca/~g_will/pyExtenDL.shtml>`_
+ Document describing how to use Borland's free command-line C++ compiler to build
+ Python.
+
+
+GNU C / Cygwin / MinGW
+^^^^^^^^^^^^^^^^^^^^^^
+
+This section describes the necessary steps to use Distutils with the GNU C/C++
+compilers in their Cygwin and MinGW distributions. [#]_ For a Python interpreter
+that was built with Cygwin, everything should work without any of these
+following steps.
+
+Not all extensions can be built with MinGW or Cygwin, but many can. Extensions
+most likely to not work are those that use C++ or depend on Microsoft Visual C
+extensions.
+
+To let Distutils compile your extension with Cygwin you have to type::
+
+ python setup.py build --compiler=cygwin
+
+and for Cygwin in no-cygwin mode [#]_ or for MinGW type::
+
+ python setup.py build --compiler=mingw32
+
+If you want to use any of these options/compilers as default, you should
+consider writing it in your personal or system-wide configuration file for
+Distutils (see section :ref:`inst-config-files`.)
+
+Older Versions of Python and MinGW
+""""""""""""""""""""""""""""""""""
+The following instructions only apply if you're using a version of Python
+inferior to 2.4.1 with a MinGW inferior to 3.0.0 (with
+binutils-2.13.90-20030111-1).
+
+These compilers require some special libraries. This task is more complex than
+for Borland's C++, because there is no program to convert the library. First
+you have to create a list of symbols which the Python DLL exports. (You can find
+a good program for this task at
+http://www.emmestech.com/software/pexports-0.43/download_pexports.html).
+
+.. I don't understand what the next line means. --amk
+.. (inclusive the references on data structures.)
+
+::
+
+ pexports python25.dll >python25.def
+
+The location of an installed :file:`python25.dll` will depend on the
+installation options and the version and language of Windows. In a "just for
+me" installation, it will appear in the root of the installation directory. In
+a shared installation, it will be located in the system directory.
+
+Then you can create from these information an import library for gcc. ::
+
+ /cygwin/bin/dlltool --dllname python25.dll --def python25.def --output-lib libpython25.a
+
+The resulting library has to be placed in the same directory as
+:file:`python25.lib`. (Should be the :file:`libs` directory under your Python
+installation directory.)
+
+If your extension uses other libraries (zlib,...) you might have to convert
+them too. The converted files have to reside in the same directories as the
+normal libraries do.
+
+
+.. seealso::
+
+ `Building Python modules on MS Windows platform with MinGW <http://www.zope.org/Members/als/tips/win32_mingw_modules>`_
+ Information about building the required libraries for the MinGW environment.
+
+
+.. rubric:: Footnotes
+
+.. [#] This also means you could replace all existing COFF-libraries with OMF-libraries
+ of the same name.
+
+.. [#] Check http://sources.redhat.com/cygwin/ and http://www.mingw.org/ for more
+ information
+
+.. [#] Then you have no POSIX emulation available, but you also don't need
+ :file:`cygwin1.dll`.
projects / python / commitdiff