mirror of https://github.com/python/cpython
1030 lines
46 KiB
ReStructuredText
1030 lines
46 KiB
ReStructuredText
.. highlightlang:: none
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====================================
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Installing Python projects: overwiew
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====================================
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.. _packaging-install-intro:
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Introduction
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============
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Although Python's extensive standard library covers many programming needs,
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there often comes a time when you need to add new functionality to your Python
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installation in the form of third-party modules. This might be necessary to
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support your own programming, or to support an application that you want to use
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and that happens to be written in Python.
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In the past, there was little support for adding third-party modules to an
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existing Python installation. With the introduction of the Python Distribution
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Utilities (Distutils for short) in Python 2.0, this changed. However, not all
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problems were solved; end-users had to rely on ``easy_install`` or
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``pip`` to download third-party modules from PyPI, uninstall distributions or do
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other maintenance operations. Packaging is a more complete replacement for
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Distutils, in the standard library, with a backport named Distutils2 available
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for older Python versions.
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This document is aimed primarily at people who need to install third-party
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Python modules: end-users and system administrators who just need to get some
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Python application running, and existing Python programmers who want to add
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new goodies to their toolbox. You don't need to know Python to read this
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document; there will be some brief forays into using Python's interactive mode
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to explore your installation, but that's it. If you're looking for information
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on how to distribute your own Python modules so that others may use them, see
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the :ref:`packaging-index` manual.
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.. _packaging-trivial-install:
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Best case: trivial installation
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-------------------------------
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In the best case, someone will have prepared a special version of the module
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distribution you want to install that is targeted specifically at your platform
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and can be installed just like any other software on your platform. For example,
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the module's developer might make an executable installer available for Windows
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users, an RPM package for users of RPM-based Linux systems (Red Hat, SuSE,
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Mandrake, and many others), a Debian package for users of Debian and derivative
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systems, and so forth.
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In that case, you would use the standard system tools to download and install
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the specific installer for your platform and its dependencies.
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Of course, things will not always be that easy. You might be interested in a
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module whose distribution doesn't have an easy-to-use installer for your
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platform. In that case, you'll have to start with the source distribution
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released by the module's author/maintainer. Installing from a source
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distribution is not too hard, as long as the modules are packaged in the
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standard way. The bulk of this document addresses the building and installing
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of modules from standard source distributions.
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.. _packaging-distutils:
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The Python standard: Distutils
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------------------------------
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If you download a source distribution of a module, it will be obvious whether
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it was packaged and distributed using Distutils. First, the distribution's name
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and version number will be featured prominently in the name of the downloaded
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archive, e.g. :file:`foo-1.0.tar.gz` or :file:`widget-0.9.7.zip`. Next, the
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archive will unpack into a similarly-named directory: :file:`foo-1.0` or
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:file:`widget-0.9.7`. Additionally, the distribution may contain a
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:file:`setup.cfg` file and a file named :file:`README.txt` ---or possibly just
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:file:`README`--- explaining that building and installing the module
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distribution is a simple matter of issuing the following command at your shell's
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prompt::
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python setup.py install
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Third-party projects have extended Distutils to work around its limitations or
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add functionality. After some years of near-inactivity in Distutils, a new
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maintainer has started to standardize good ideas in PEPs and implement them in a
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new, improved version of Distutils, called Distutils2 or Packaging.
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.. _packaging-new-standard:
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The new standard: Packaging
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---------------------------
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The rules described in the first paragraph above apply to Packaging-based
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projects too: a source distribution will have a name like
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:file:`widget-0.9.7.zip`. One of the main differences with Distutils is that
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distributions no longer have a :file:`setup.py` script; it used to cause a
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number of issues. Now there is a unique script installed with Python itself::
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pysetup install widget-0.9.7.zip
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Running this command is enough to build and install projects (Python modules or
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packages, scripts or whole applications), without even having to unpack the
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archive. It is also compatible with Distutils-based distributions.
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Unless you have to perform non-standard installations or customize the build
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process, you can stop reading this manual ---the above command is everything you
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need to get out of it.
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With :program:`pysetup`, you won't even have to manually download a distribution
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before installing it; see :ref:`packaging-pysetup`.
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.. _packaging-standard-install:
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Standard build and install
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==========================
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As described in section :ref:`packaging-new-standard`, building and installing
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a module distribution using Packaging usually comes down to one simple
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command::
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pysetup run install_dist
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How you actually run this command depends on the platform and the command line
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interface it provides:
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* **Unix**: Use a shell prompt.
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* **Windows**: Open a command prompt ("DOS console") or use :command:`Powershell`.
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* **OS X**: Open a :command:`Terminal`.
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.. _packaging-platform-variations:
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Platform variations
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-------------------
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The setup command is meant to be run from the root directory of the source
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distribution, i.e. the top-level subdirectory that the module source
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distribution unpacks into. For example, if you've just downloaded a module
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source distribution :file:`foo-1.0.tar.gz` onto a Unix system, the normal
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steps to follow are these::
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gunzip -c foo-1.0.tar.gz | tar xf - # unpacks into directory foo-1.0
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cd foo-1.0
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pysetup run install_dist
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On Windows, you'd probably download :file:`foo-1.0.zip`. If you downloaded the
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archive file to :file:`C:\\Temp`, then it would unpack into
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:file:`C:\\Temp\\foo-1.0`. To actually unpack the archive, you can use either
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an archive manipulator with a graphical user interface (such as WinZip or 7-Zip)
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or a command-line tool (such as :program:`unzip`, :program:`pkunzip` or, again,
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:program:`7z`). Then, open a command prompt window ("DOS box" or
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Powershell), and run::
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cd c:\Temp\foo-1.0
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pysetup run install_dist
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.. _packaging-splitting-up:
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Splitting the job up
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--------------------
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Running ``pysetup run install_dist`` builds and installs all modules in one go. If you
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prefer to work incrementally ---especially useful if you want to customize the
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build process, or if things are going wrong--- you can use the setup script to
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do one thing at a time. This is a valuable tool when different users will perform
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separately the build and install steps. For example, you might want to build a
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module distribution and hand it off to a system administrator for installation
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(or do it yourself, but with super-user or admin privileges).
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For example, to build everything in one step and then install everything
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in a second step, you aptly invoke two distinct Packaging commands::
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pysetup run build
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pysetup run install_dist
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If you do this, you will notice that invoking the :command:`install_dist` command
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first runs the :command:`build` command, which ---in this case--- quickly
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notices it can spare itself the work, since everything in the :file:`build`
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directory is up-to-date.
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You may often ignore this ability to divide the process in steps if all you do
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is installing modules downloaded from the Internet, but it's very handy for
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more advanced tasks. If you find yourself in the need for distributing your own
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Python modules and extensions, though, you'll most likely run many individual
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Packaging commands.
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.. _packaging-how-build-works:
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How building works
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------------------
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As implied above, the :command:`build` command is responsible for collecting
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and placing the files to be installed into a *build directory*. By default,
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this is :file:`build`, under the distribution root. If you're excessively
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concerned with speed, or want to keep the source tree pristine, you can specify
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a different build directory with the :option:`--build-base` option. For example::
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pysetup run build --build-base /tmp/pybuild/foo-1.0
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(Or you could do this permanently with a directive in your system or personal
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Packaging configuration file; see section :ref:`packaging-config-files`.)
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In the usual case, however, all this is unnecessary.
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The build tree's default layout looks like so::
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--- build/ --- lib/
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or
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--- build/ --- lib.<plat>/
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temp.<plat>/
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where ``<plat>`` expands to a brief description of the current OS/hardware
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platform and Python version. The first form, with just a :file:`lib` directory,
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is used for pure module distributions (module distributions that
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include only pure Python modules). If a module distribution contains any
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extensions (modules written in C/C++), then the second form, with two ``<plat>``
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directories, is used. In that case, the :file:`temp.{plat}` directory holds
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temporary files generated during the compile/link process which are not intended
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to be installed. In either case, the :file:`lib` (or :file:`lib.{plat}`) directory
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contains all Python modules (pure Python and extensions) to be installed.
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In the future, more directories will be added to handle Python scripts,
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documentation, binary executables, and whatever else is required to install
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Python modules and applications.
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.. _packaging-how-install-works:
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How installation works
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----------------------
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After the :command:`build` command is run (whether explicitly or by the
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:command:`install_dist` command on your behalf), the work of the :command:`install_dist`
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command is relatively simple: all it has to do is copy the contents of
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:file:`build/lib` (or :file:`build/lib.{plat}`) to the installation directory
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of your choice.
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If you don't choose an installation directory ---i.e., if you just run
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``pysetup run install_dist``\ --- then the :command:`install_dist` command
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installs to the standard location for third-party Python modules. This location
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varies by platform and depending on how you built/installed Python itself. On
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Unix (and Mac OS X, which is also Unix-based), it also depends on whether the
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module distribution being installed is pure Python or contains extensions
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("non-pure"):
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+-----------------+-----------------------------------------------------+--------------------------------------------------+-------+
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| Platform | Standard installation location | Default value | Notes |
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+=================+=====================================================+==================================================+=======+
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| Unix (pure) | :file:`{prefix}/lib/python{X.Y}/site-packages` | :file:`/usr/local/lib/python{X.Y}/site-packages` | \(1) |
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+-----------------+-----------------------------------------------------+--------------------------------------------------+-------+
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| Unix (non-pure) | :file:`{exec-prefix}/lib/python{X.Y}/site-packages` | :file:`/usr/local/lib/python{X.Y}/site-packages` | \(1) |
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+-----------------+-----------------------------------------------------+--------------------------------------------------+-------+
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| Windows | :file:`{prefix}\\Lib\\site-packages` | :file:`C:\\Python{XY}\\Lib\\site-packages` | \(2) |
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+-----------------+-----------------------------------------------------+--------------------------------------------------+-------+
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Notes:
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(1)
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Most Linux distributions include Python as a standard part of the system, so
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:file:`{prefix}` and :file:`{exec-prefix}` are usually both :file:`/usr` on
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Linux. If you build Python yourself on Linux (or any Unix-like system), the
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default :file:`{prefix}` and :file:`{exec-prefix}` are :file:`/usr/local`.
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(2)
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The default installation directory on Windows was :file:`C:\\Program
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Files\\Python` under Python 1.6a1, 1.5.2, and earlier.
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:file:`{prefix}` and :file:`{exec-prefix}` stand for the directories that Python
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is installed to, and where it finds its libraries at run-time. They are always
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the same under Windows, and very often the same under Unix and Mac OS X. You
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can find out what your Python installation uses for :file:`{prefix}` and
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:file:`{exec-prefix}` by running Python in interactive mode and typing a few
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simple commands.
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.. TODO link to Doc/using instead of duplicating
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To start the interactive Python interpreter, you need to follow a slightly
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different recipe for each platform. Under Unix, just type :command:`python` at
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the shell prompt. Under Windows (assuming the Python executable is on your
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:envvar:`PATH`, which is the usual case), you can choose :menuselection:`Start --> Run`,
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type ``python`` and press ``enter``. Alternatively, you can simply execute
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:command:`python` at a command prompt ("DOS console" or Powershell).
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Once the interpreter is started, you type Python code at the prompt. For
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example, on my Linux system, I type the three Python statements shown below,
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and get the output as shown, to find out my :file:`{prefix}` and :file:`{exec-prefix}`::
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Python 3.3 (r32:88445, Apr 2 2011, 10:43:54)
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Type "help", "copyright", "credits" or "license" for more information.
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>>> import sys
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>>> sys.prefix
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'/usr'
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>>> sys.exec_prefix
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'/usr'
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If you don't want to install modules to the standard location, or if you don't
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have permission to write there, then you need to read about alternate
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installations in section :ref:`packaging-alt-install`. If you want to customize your
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installation directories more heavily, see section :ref:`packaging-custom-install`.
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.. _packaging-alt-install:
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Alternate installation
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======================
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Often, it is necessary or desirable to install modules to a location other than
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the standard location for third-party Python modules. For example, on a Unix
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system you might not have permission to write to the standard third-party module
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directory. Or you might wish to try out a module before making it a standard
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part of your local Python installation. This is especially true when upgrading
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a distribution already present: you want to make sure your existing base of
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scripts still works with the new version before actually upgrading.
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The Packaging :command:`install_dist` command is designed to make installing module
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distributions to an alternate location simple and painless. The basic idea is
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that you supply a base directory for the installation, and the
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:command:`install_dist` command picks a set of directories (called an *installation
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scheme*) under this base directory in which to install files. The details
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differ across platforms, so read whichever of the following sections applies to
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you.
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.. _packaging-alt-install-prefix:
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Alternate installation: the home scheme
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---------------------------------------
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The idea behind the "home scheme" is that you build and maintain a personal
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stash of Python modules. This scheme's name is derived from the concept of a
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"home" directory on Unix, since it's not unusual for a Unix user to make their
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home directory have a layout similar to :file:`/usr/` or :file:`/usr/local/`.
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In spite of its name's origin, this scheme can be used by anyone, regardless
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of the operating system.
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Installing a new module distribution in this way is as simple as ::
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pysetup run install_dist --home <dir>
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where you can supply any directory you like for the :option:`--home` option. On
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Unix, lazy typists can just type a tilde (``~``); the :command:`install_dist` command
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will expand this to your home directory::
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pysetup run install_dist --home ~
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The :option:`--home` option defines the base directory for the installation.
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Under it, files are installed to the following directories:
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+------------------------------+---------------------------+-----------------------------+
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| Type of file | Installation Directory | Override option |
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+==============================+===========================+=============================+
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| pure module distribution | :file:`{home}/lib/python` | :option:`--install-purelib` |
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+------------------------------+---------------------------+-----------------------------+
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| non-pure module distribution | :file:`{home}/lib/python` | :option:`--install-platlib` |
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+------------------------------+---------------------------+-----------------------------+
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| scripts | :file:`{home}/bin` | :option:`--install-scripts` |
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+------------------------------+---------------------------+-----------------------------+
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| data | :file:`{home}/share` | :option:`--install-data` |
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+------------------------------+---------------------------+-----------------------------+
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.. _packaging-alt-install-home:
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Alternate installation: Unix (the prefix scheme)
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------------------------------------------------
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The "prefix scheme" is useful when you wish to use one Python installation to
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run the build command, but install modules into the third-party module directory
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of a different Python installation (or something that looks like a different
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Python installation). If this sounds a trifle unusual, it is ---that's why the
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"home scheme" comes first. However, there are at least two known cases where the
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prefix scheme will be useful.
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First, consider that many Linux distributions put Python in :file:`/usr`, rather
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than the more traditional :file:`/usr/local`. This is entirely appropriate,
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since in those cases Python is part of "the system" rather than a local add-on.
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However, if you are installing Python modules from source, you probably want
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them to go in :file:`/usr/local/lib/python2.{X}` rather than
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:file:`/usr/lib/python2.{X}`. This can be done with ::
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pysetup run install_dist --prefix /usr/local
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Another possibility is a network filesystem where the name used to write to a
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remote directory is different from the name used to read it: for example, the
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Python interpreter accessed as :file:`/usr/local/bin/python` might search for
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modules in :file:`/usr/local/lib/python2.{X}`, but those modules would have to
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be installed to, say, :file:`/mnt/{@server}/export/lib/python2.{X}`. This could
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be done with ::
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pysetup run install_dist --prefix=/mnt/@server/export
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In either case, the :option:`--prefix` option defines the installation base, and
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the :option:`--exec-prefix` option defines the platform-specific installation
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base, which is used for platform-specific files. (Currently, this just means
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non-pure module distributions, but could be expanded to C libraries, binary
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executables, etc.) If :option:`--exec-prefix` is not supplied, it defaults to
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:option:`--prefix`. Files are installed as follows:
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+------------------------------+-----------------------------------------------------+-----------------------------+
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| Type of file | Installation Directory | Override option |
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+==============================+=====================================================+=============================+
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| pure module distribution | :file:`{prefix}/lib/python{X.Y}/site-packages` | :option:`--install-purelib` |
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+------------------------------+-----------------------------------------------------+-----------------------------+
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| non-pure module distribution | :file:`{exec-prefix}/lib/python{X.Y}/site-packages` | :option:`--install-platlib` |
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+------------------------------+-----------------------------------------------------+-----------------------------+
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| scripts | :file:`{prefix}/bin` | :option:`--install-scripts` |
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+------------------------------+-----------------------------------------------------+-----------------------------+
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| data | :file:`{prefix}/share` | :option:`--install-data` |
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+------------------------------+-----------------------------------------------------+-----------------------------+
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There is no requirement that :option:`--prefix` or :option:`--exec-prefix`
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actually point to an alternate Python installation; if the directories listed
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above do not already exist, they are created at installation time.
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Incidentally, the real reason the prefix scheme is important is simply that a
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standard Unix installation uses the prefix scheme, but with :option:`--prefix`
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and :option:`--exec-prefix` supplied by Python itself as ``sys.prefix`` and
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``sys.exec_prefix``. Thus, you might think you'll never use the prefix scheme,
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but every time you run ``pysetup run install_dist`` without any other
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options, you're using it.
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Note that installing extensions to an alternate Python installation doesn't have
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anything to do with how those extensions are built: in particular, extensions
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will be compiled using the Python header files (:file:`Python.h` and friends)
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installed with the Python interpreter used to run the build command. It is
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therefore your responsibility to ensure compatibility between the interpreter
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intended to run extensions installed in this way and the interpreter used to
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build these same extensions. To avoid problems, it is best to make sure that
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the two interpreters are the same version of Python (possibly different builds,
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or possibly copies of the same build). (Of course, if your :option:`--prefix`
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and :option:`--exec-prefix` don't even point to an alternate Python installation,
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this is immaterial.)
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.. _packaging-alt-install-windows:
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Alternate installation: Windows (the prefix scheme)
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---------------------------------------------------
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Windows has a different and vaguer notion of home directories than Unix, and
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since its standard Python installation is simpler, the :option:`--prefix` option
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has traditionally been used to install additional packages to arbitrary
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locations. ::
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pysetup run install_dist --prefix "\Temp\Python"
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to install modules to the :file:`\\Temp\\Python` directory on the current drive.
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The installation base is defined by the :option:`--prefix` option; the
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:option:`--exec-prefix` option is unsupported under Windows. Files are
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installed as follows:
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+------------------------------+---------------------------+-----------------------------+
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| 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` |
|
|
+------------------------------+---------------------------+-----------------------------+
|
|
|
|
|
|
.. _packaging-custom-install:
|
|
|
|
Custom installation
|
|
===================
|
|
|
|
Sometimes, the alternate installation schemes described in section
|
|
:ref:`packaging-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 and, in this case, it makes most sense to supply
|
|
a relative path, which will be interpreted relative to the installation base
|
|
directory (in our example, your home directory)::
|
|
|
|
pysetup run install_dist --home ~ --install-scripts scripts
|
|
|
|
Another Unix example: suppose your Python installation was built and installed
|
|
with a prefix of :file:`/usr/local/python`. Thus, in 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::
|
|
|
|
pysetup run install_dist --install-scripts /usr/local/bin
|
|
|
|
This command performs an installation using the "prefix scheme", where the
|
|
prefix is whatever your Python interpreter was installed with ---in this case,
|
|
:file:`/usr/local/python`.
|
|
|
|
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::
|
|
|
|
pysetup run install_dist --install-purelib Site --install-platlib Site
|
|
|
|
.. XXX Nothing is installed right under prefix in windows, is it??
|
|
|
|
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:`packaging-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. Using relative paths is recommended here.
|
|
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::
|
|
|
|
pysetup run install_dist --home ~ \
|
|
--install-purelib python/lib \
|
|
--install-platlib python/'lib.$PLAT' \
|
|
--install-scripts python/scripts \
|
|
--install-data python/data
|
|
|
|
or, equivalently, ::
|
|
|
|
pysetup run install_dist --home ~/python \
|
|
--install-purelib lib \
|
|
--install-platlib 'lib.$PLAT' \
|
|
--install-scripts scripts \
|
|
--install-data data
|
|
|
|
``$PLAT`` doesn't need to be defined as an environment variable ---it will also
|
|
be expanded by Packaging as it parses your command line options, just as it
|
|
does when parsing your configuration file(s). (More on that later.)
|
|
|
|
Obviously, specifying the entire installation scheme every time you install a
|
|
new module distribution would be very tedious. To spare you all that work, you
|
|
can store it in a Packaging configuration file instead (see section
|
|
:ref:`packaging-config-files`), like so::
|
|
|
|
[install_dist]
|
|
install-base = $HOME
|
|
install-purelib = python/lib
|
|
install-platlib = python/lib.$PLAT
|
|
install-scripts = python/scripts
|
|
install-data = python/data
|
|
|
|
or, equivalently, ::
|
|
|
|
[install_dist]
|
|
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 override their installation
|
|
base directory when running the setup script. For example, ::
|
|
|
|
pysetup run install_dist --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'd probably
|
|
want to supply an installation base of :file:`/tmp/python`.)
|
|
|
|
You may have noticed the use of ``$HOME`` and ``$PLAT`` in the sample
|
|
configuration file. These are Packaging configuration variables, which
|
|
bear a strong resemblance to environment variables. In fact, you can use
|
|
environment variables in configuration files on platforms that have such a notion, but
|
|
Packaging additionally defines a few extra variables that may not be in your
|
|
environment, such as ``$PLAT``. Of course, on systems that don't have
|
|
environment variables, such as Mac OS 9, the configuration variables supplied by
|
|
the Packaging are the only ones you can use. See section :ref:`packaging-config-files`
|
|
for details.
|
|
|
|
.. XXX which vars win out eventually in case of clash env or Packaging?
|
|
|
|
.. XXX need some Windows examples---when would custom installation schemes be
|
|
needed on those platforms?
|
|
|
|
|
|
.. XXX Move this section to Doc/using
|
|
|
|
.. _packaging-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 this path is configured into the Python binary when the interpreter is built.
|
|
You can obtain the search 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 choose a different
|
|
location for some reason. For example, if your site kept by convention all web
|
|
server-related software under :file:`/www`. Add-on Python modules might then
|
|
belong in :file:`/www/python`, and in order to import them, this directory would
|
|
have to be added to ``sys.path``. There are several ways to solve this problem.
|
|
|
|
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 3.3 to 3.3.1, 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.
|
|
|
|
Alternatively, 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 non-existent paths.)
|
|
|
|
Finally, ``sys.path`` is just a regular Python list, so any Python application
|
|
can modify it by adding or removing entries.
|
|
|
|
|
|
.. _packaging-config-files:
|
|
|
|
Configuration files for Packaging
|
|
=================================
|
|
|
|
As mentioned above, you can use configuration files to store personal or site
|
|
preferences for any option supported by any Packaging command. Depending on your
|
|
platform, you can use one of two or three possible configuration files. These
|
|
files will be read before parsing the command-line, so they take precedence over
|
|
default values. In turn, the command-line will override configuration files.
|
|
Lastly, if there are multiple configuration files, values from files read
|
|
earlier will be overridden by values from files read later.
|
|
|
|
.. XXX "one of two or three possible..." seems wrong info. Below always 3 files
|
|
are indicated in the tables.
|
|
|
|
|
|
.. _packaging-config-filenames:
|
|
|
|
Location and names of configuration files
|
|
-----------------------------------------
|
|
|
|
The name and location of the configuration files vary slightly across
|
|
platforms. On Unix and Mac OS X, these are the three configuration files listed
|
|
in the order they are processed:
|
|
|
|
+--------------+----------------------------------------------------------+-------+
|
|
| Type of file | Location and filename | Notes |
|
|
+==============+==========================================================+=======+
|
|
| system | :file:`{prefix}/lib/python{ver}/packaging/packaging.cfg` | \(1) |
|
|
+--------------+----------------------------------------------------------+-------+
|
|
| personal | :file:`$HOME/.pydistutils.cfg` | \(2) |
|
|
+--------------+----------------------------------------------------------+-------+
|
|
| local | :file:`setup.cfg` | \(3) |
|
|
+--------------+----------------------------------------------------------+-------+
|
|
|
|
Similarly, the configuration files on Windows ---also listed in the order they
|
|
are processed--- are these:
|
|
|
|
+--------------+-------------------------------------------------+-------+
|
|
| Type of file | Location and filename | Notes |
|
|
+==============+=================================================+=======+
|
|
| system | :file:`{prefix}\\Lib\\packaging\\packaging.cfg` | \(4) |
|
|
+--------------+-------------------------------------------------+-------+
|
|
| personal | :file:`%HOME%\\pydistutils.cfg` | \(5) |
|
|
+--------------+-------------------------------------------------+-------+
|
|
| local | :file:`setup.cfg` | \(3) |
|
|
+--------------+-------------------------------------------------+-------+
|
|
|
|
On all platforms, the *personal* file can be temporarily disabled by
|
|
means of the `--no-user-cfg` option.
|
|
|
|
Notes:
|
|
|
|
(1)
|
|
Strictly speaking, the system-wide configuration file lives in the directory
|
|
where Packaging is installed.
|
|
|
|
(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. Packaging uses the
|
|
:func:`os.path.expanduser` function to do this.
|
|
|
|
(3)
|
|
I.e., in the current directory (usually the location of the setup script).
|
|
|
|
(4)
|
|
(See also note (1).) Python's default installation prefix is
|
|
:file:`C:\\Python`, so the system configuration file is normally
|
|
:file:`C:\\Python\\Lib\\packaging\\packaging.cfg`.
|
|
|
|
(5)
|
|
On Windows, if the :envvar:`HOME` environment variable is not defined,
|
|
:envvar:`USERPROFILE` then :envvar:`HOMEDRIVE` and :envvar:`HOMEPATH` will
|
|
be tried. Packaging uses the :func:`os.path.expanduser` function to do this.
|
|
|
|
|
|
.. _packaging-config-syntax:
|
|
|
|
Syntax of configuration files
|
|
-----------------------------
|
|
|
|
All Packaging configuration files share the same syntax. Options defined in
|
|
them are grouped into sections, and each Packaging command gets its own section.
|
|
Additionally, there's a ``global`` section for options that affect every command.
|
|
Sections consist of one or more lines containing a single option specified as
|
|
``option = value``.
|
|
|
|
For example, here's a complete configuration file that forces all commands to
|
|
run quietly by default::
|
|
|
|
[global]
|
|
verbose = 0
|
|
|
|
If this was the system configuration file, it would affect all processing
|
|
of any Python module distribution by any user on the current system. If it was
|
|
installed as your personal configuration file (on systems that support them),
|
|
it would affect only module distributions processed by you. Lastly, if it was
|
|
used as the :file:`setup.cfg` for a particular module distribution, it would
|
|
affect that distribution only.
|
|
|
|
.. XXX "(on systems that support them)" seems wrong info
|
|
|
|
If you wanted to, 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::
|
|
|
|
pysetup run 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 configuration files
|
|
has no such implication; it only means that if the command is run, the options
|
|
for it in the configuration file will apply. (This is also true if you run
|
|
other commands that derive values from it.)
|
|
|
|
You can find out the complete list of options for any command using the
|
|
:option:`--help` option, e.g.::
|
|
|
|
pysetup run build --help
|
|
|
|
and you can find out the complete list of global options by using
|
|
:option:`--help` without a command::
|
|
|
|
pysetup run --help
|
|
|
|
See also the "Reference" section of the "Distributing Python Modules" manual.
|
|
|
|
.. XXX no links to the relevant section exist.
|
|
|
|
|
|
.. _packaging-building-ext:
|
|
|
|
Building extensions: tips and tricks
|
|
====================================
|
|
|
|
Whenever possible, Packaging tries to use the configuration information made
|
|
available by the Python interpreter used to run `pysetup`.
|
|
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 Packaging behaviour.
|
|
|
|
|
|
.. _packaging-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.
|
|
|
|
.. TODO update to new setup.cfg
|
|
|
|
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 ``pysetup run 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.
|
|
|
|
|
|
.. _packaging-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 Packaging 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 Packaging manage to use these libraries with their changed names? If
|
|
the extension needs a library (eg. :file:`foo`) Packaging 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 Packaging compile your extension with Borland, C++ you now have to
|
|
type::
|
|
|
|
pysetup run 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 Packaging (see
|
|
section :ref:`packaging-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 Packaging 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 Packaging compile your extension with Cygwin, you have to type::
|
|
|
|
pysetup run build --compiler=cygwin
|
|
|
|
and for Cygwin in no-cygwin mode [#]_ or for MinGW, type::
|
|
|
|
pysetup run 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
|
|
Packaging (see section :ref:`packaging-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
|
|
:file:`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`.
|