Installing lxml
===============

For special installation instructions regarding MS Windows and
MacOS-X, see below.

.. contents::
..
   1  Requirements
   2  Installation
   3  Installation in ActivePython
   4  Building lxml from sources
   5  MS Windows
   6  MacOS-X


Requirements
------------

You need Python 2.3 or later.

Unless you are using a static binary distribution (e.g. a Windows
binary egg from PyPI), you need to install libxml2 and libxslt, in
particular:

* libxml 2.6.21 or later. It can be found here:
  http://xmlsoft.org/downloads.html

  If you want to use XPath, do not use libxml2 2.6.27.  We recommend
  libxml2 2.7.2 or later.

* libxslt 1.1.15 or later. It can be found here:
  http://xmlsoft.org/XSLT/downloads.html

Newer versions generally contain less bugs and are therefore
recommended.  XML Schema support is also still worked on in libxml2,
so newer versions will give you better complience with the W3C spec.


Installation
------------

Get the `easy_install`_ tool and run the following as super-user (or
administrator)::

  easy_install lxml

.. _easy_install: http://peak.telecommunity.com/DevCenter/EasyInstall

* On **MS Windows**, the above will install the binary builds that we
  provide.  If there is no binary build of the latest release yet,
  please search PyPI_ for the last release that has them and pass that
  version to ``easy_install`` like this::

    easy_install lxml==2.2.2

* On **Linux** (and most other well-behaved operating systems),
  ``easy_install`` will manage to build the source distribution as
  long as libxml2 and libxslt are properly installed, including
  development packages, i.e. header files, etc.  Use your package
  management tool to look for packages like ``libxml2-dev`` or
  ``libxslt-devel`` if the build fails, and make sure they are
  installed.

* On **MacOS-X**, use the following to build the source distribution,
  and make sure you have a working Internet connection, as this will
  download libxml2 and libxslt in order to build them::

   STATIC_DEPS=true easy_install lxml

.. _PyPI: http://cheeseshop.python.org/pypi/lxml


Installation in ActivePython
----------------------------

ActiveState_ provides ready-made lxml builds for different platforms
in its `package repository`_ for the PyPM_ package manager.  PyPM is
similar to apt-get in that there is a repository of automaticaly
pre-built packages for Windows, Mac and Linux.

To install lxml in ActivePython, type the following on one of these
operating systems::

  $ pypm install lxml

To test the installation, try::

  $ python -c "import lxml; print lxml.__file__"

This should show you the directory where the package was installed.

.. _ActiveState: http://www.activestate.com/
.. _PyPM: http://docs.activestate.com/activepython/2.6/pypm.html
.. _`package repository`: http://pypm.activestate.com/


Building lxml from sources
--------------------------

If you want to build lxml from SVN you should read `how to build lxml
from source`_ (or the file ``doc/build.txt`` in the source tree).
Building from Subversion sources or from modified distribution sources
requires Cython_ to translate the lxml sources into C code.  The
source distribution ships with pre-generated C source files, so you do
not need Cython installed to build from release sources.

.. _Cython: http://www.cython.org
.. _`how to build lxml from source`: build.html

If you have read these instructions and still cannot manage to install lxml,
you can check the archives of the `mailing list`_ to see if your problem is
known or otherwise send a mail to the list.

 .. _`mailing list`: http://codespeak.net/mailman/listinfo/lxml-dev


MS Windows
----------

For MS Windows, the `binary egg distribution of lxml`_ is statically
built against the libraries, i.e. it already includes them.  There is
no need to install the external libraries if you use an official lxml
build from PyPI.

Unless you know what you are doing, this means: *do not install
libxml2 or libxslt if you use a binary build of lxml*.  Just use
``easy_install`` by following the installation instructions above.

*Only* if you want to upgrade the libraries and/or compile lxml from
sources, you should install a `binary distribution`_ of libxml2 and
libxslt.  You need both libxml2 and libxslt, as well as iconv and
zlib.

.. _`binary distribution`: http://www.zlatkovic.com/libxml.en.html
.. _`binary egg distribution of lxml`: http://cheeseshop.python.org/pypi/lxml


MacOS-X
-------

A macport of lxml is available.  Try ``port install py25-lxml``.

If you want to use a more recent lxml release, you may have to build
it yourself.  Apple doesn't help here, as the system libraries of
libxml2 and libxslt installed under MacOS-X are horribly outdated, and
updating them is everything but easy.  In any case, you cannot run
lxml 2.x with the system provided libraries, so you have to use newer
libraries.

Luckily, lxml's ``setup.py`` script has built-in support for building
and integrating these libraries statically during the build.  Please
read the `MacOS-X build instructions`_.

.. _`MacOS-X build instructions`: build.html#building-lxml-on-macos-x
.. _fink: http://finkproject.org/

A number of users also reported success with updated libraries
(e.g. using fink_ or macports), but needed to set the runtime
environment variable ``DYLD_LIBRARY_PATH`` to the directory where fink
keeps the libraries.  In any case, this method is easy to get wrong
and everything but safe.  Unless you know what you are doing, follow
the static build instructions above.
