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10 </style><title>Python and bindings</title></head><body bgcolor="#8b7765" text="#000000" link="#000000" vlink="#000000"><table border="0" width="100%" cellpadding="5" cellspacing="0" align="center"><tr><td width="120"><a href="http://swpat.ffii.org/"><img src="epatents.png" alt="Action against software patents" /></a></td><td width="100"><a href="http://www.gnome.org/"><img src="gnome2.png" alt="Gnome2 Logo" /></a><a href="http://www.redhat.com"><img src="redhat.gif" alt="Red Hat Logo" /></a><div align="left"><a href="http://xmlsoft.org/XSLT/"><img src="Libxslt-Logo-180x168.gif" alt="Made with Libxslt Logo" /></a></div></td><td><table border="0" width="90%" cellpadding="2" cellspacing="0" align="center" bgcolor="#000000"><tr><td><table width="100%" border="0" cellspacing="1" cellpadding="3" bgcolor="#fffacd"><tr><td align="center"><h1>The XSLT C library for Gnome</h1><h2>Python and bindings</h2></td></tr></table></td></tr></table></td></tr></table><table border="0" cellpadding="4" cellspacing="0" width="100%" align="center"><tr><td bgcolor="#8b7765"><table border="0" cellspacing="0" cellpadding="2" width="100%"><tr><td valign="top" width="200" bgcolor="#8b7765"><table border="0" cellspacing="0" cellpadding="1" width="100%" bgcolor="#000000"><tr><td><table width="100%" border="0" cellspacing="1" cellpadding="3"><tr><td colspan="1" bgcolor="#eecfa1" align="center"><center><b>Main Menu</b></center></td></tr><tr><td bgcolor="#fffacd"><form action="search.php" enctype="application/x-www-form-urlencoded" method="get"><input name="query" type="text" size="20" value="" /><input name="submit" type="submit" value="Search ..." /></form><ul><li><a href="index.html">Home</a></li><li><a href="intro.html">Introduction</a></li><li><a href="docs.html">Documentation</a></li><li><a href="bugs.html">Reporting bugs and getting help</a></li><li><a href="help.html">How to help</a></li><li><a href="downloads.html">Downloads</a></li><li><a href="FAQ.html">FAQ</a></li><li><a href="news.html">News</a></li><li><a href="xsltproc2.html">The xsltproc tool</a></li><li><a href="docbook.html">DocBook</a></li><li><a href="API.html">The programming API</a></li><li><a href="python.html">Python and bindings</a></li><li><a href="internals.html">Library internals</a></li><li><a href="extensions.html">Writing extensions</a></li><li><a href="contribs.html">Contributions</a></li><li><a href="xslt.html">flat page</a>, <a href="site.xsl">stylesheet</a></li></ul></td></tr></table><table width="100%" border="0" cellspacing="1" cellpadding="3"><tr><td colspan="1" bgcolor="#eecfa1" align="center"><center><b>Related links</b></center></td></tr><tr><td bgcolor="#fffacd"><ul><li><a href="tutorial/libxslttutorial.html">Tutorial</a></li><li><a href="xsltproc.html">Man page for xsltproc</a></li><li><a href="http://mail.gnome.org/archives/xslt/">Mail archive</a></li><li><a href="http://xmlsoft.org/">XML libxml</a></li><li><a href="http://phd.cs.unibo.it/gdome2/">DOM gdome2</a></li><li><a href="ftp://xmlsoft.org/">FTP</a></li><li><a href="http://www.zlatkovic.com/projects/libxml/">Windows binaries</a></li><li><a href="http://garypennington.net/libxml2/">Solaris binaries</a></li><li><a href="http://www.zveno.com/open_source/libxml2xslt.html">MacOsX binaries</a></li><li><a href="http://sourceforge.net/projects/libxml2-pas/">Pascal bindings</a></li><li><a href="http://bugzilla.gnome.org/buglist.cgi?product=libxslt">Bug Tracker</a></li><li><a href="http://xsldbg.sourceforge.net/">Xsldbg Debugger</a></li><li><a href="http://www.mod-xslt.com/mod-xslt/">Apache module</a></li></ul></td></tr></table><table width="100%" border="0" cellspacing="1" cellpadding="3"><tr><td colspan="1" bgcolor="#eecfa1" align="center"><center><b>API Indexes</b></center></td></tr><tr><td bgcolor="#fffacd"><ul><li><a href="APIchunk0.html">Alphabetic</a></li><li><a href="APIconstructors.html">Constructors</a></li><li><a href="APIfunctions.html">Functions/Types</a></li><li><a href="APIfiles.html">Modules</a></li><li><a href="APIsymbols.html">Symbols</a></li></ul></td></tr></table></td></tr></table></td><td valign="top" bgcolor="#8b7765"><table border="0" cellspacing="0" cellpadding="1" width="100%"><tr><td><table border="0" cellspacing="0" cellpadding="1" width="100%" bgcolor="#000000"><tr><td><table border="0" cellpadding="3" cellspacing="1" width="100%"><tr><td bgcolor="#fffacd"><p>There is a number of language bindings and wrappers available for libxml2,
11 the list below is not exhaustive. Please contact the <a href="http://mail.gnome.org/mailman/listinfo/xml-bindings">xml-bindings@gnome.org</a>
12 (<a href="http://mail.gnome.org/archives/xml-bindings/">archives</a>) in
13 order to get updates to this list or to discuss the specific topic of libxml2
14 or libxslt wrappers or bindings:</p><ul><li><a href="http://mail.gnome.org/archives/xml/2001-March/msg00014.html">Matt
15 Sergeant</a> developped <a href="http://axkit.org/download/">XML::LibXML
16 and XML::LibXSLT</a>, Perl wrappers for libxml2/libxslt as part of the <a href="http://axkit.com/">AxKit XML application server</a></li>
17 <li><a href="mailto:dkuhlman@cutter.rexx.com">Dave Kuhlman</a> provides and
18 earlier version of the libxml/libxslt <a href="http://www.rexx.com/~dkuhlman">wrappers for Python</a></li>
19 <li>Petr Kozelka provides <a href="http://sourceforge.net/projects/libxml2-pas">Pascal units to glue
20 libxml2</a> with Kylix, Delphi and other Pascal compilers</li>
21 <li>Wai-Sun "Squidster" Chia provides <a href="http://www.rubycolor.org/arc/redist/">bindings for Ruby</a> and
22 libxml2 bindings are also available in Ruby through the <a href="http://libgdome-ruby.berlios.de/">libgdome-ruby</a> module
23 maintained by Tobias Peters.</li>
24 <li>Steve Ball and contributors maintains <a href="http://tclxml.sourceforge.net/">libxml2 and libxslt bindings for
26 <li><a href="mailto:xmlwrapp@pmade.org">Peter Jones</a> maintains C++
27 bindings for libxslt within <a href="http://pmade.org/pjones/software/xmlwrapp/">xmlwrapp</a></li>
28 <li><a href="phillim2@comcast.net">Mike Phillips</a> provides a module
29 using <a href="http://siasl.dyndns.org/projects/projects.html">libxslt
31 <li><a href="http://savannah.gnu.org/projects/classpathx/">LibxmlJ</a> is
32 an effort to create a 100% JAXP-compatible Java wrapper for libxml2 and
33 libxslt as part of GNU ClasspathX project.</li>
34 <li>Patrick McPhee provides Rexx bindings fof libxml2 and libxslt,
35 look for <a href="http://www.interlog.com/~ptjm/software.html">RexxXML</a>.
36 </li></ul><p>The libxslt Python module depends on the <a href="http://xmlsoft.org/python.html">libxml2 Python</a> module.</p><p>The distribution includes a set of Python bindings, which are garanteed to
37 be maintained as part of the library in the future, though the Python
38 interface have not yet reached the completeness of the C API.</p><p><a href="mailto:stephane.bidoul@softwareag.com">Stéphane Bidoul</a>
39 maintains <a href="http://users.skynet.be/sbi/libxml-python/">a Windows port
40 of the Python bindings</a>.</p><p>Note to people interested in building bindings, the API is formalized as
41 <a href="libxslt-api.xml">an XML API description file</a> which allows to
42 automate a large part of the Python bindings, this includes function
43 descriptions, enums, structures, typedefs, etc... The Python script used to
44 build the bindings is python/generator.py in the source distribution.</p><p>To install the Python bindings there are 2 options:</p><ul><li>If you use an RPM based distribution, simply install the <a href="http://rpmfind.net/linux/rpm2html/search.php?query=libxml2-python">libxml2-python
45 RPM</a> and the <a href="http://rpmfind.net/linux/rpm2html/search.php?query=libxslt-python">libxslt-python
47 <li>Otherwise use the <a href="ftp://xmlsoft.org/python/">libxml2-python
48 module distribution</a> corresponding to your installed version of
49 libxml2 and libxslt. Note that to install it you will need both libxml2
50 and libxslt installed and run "python setup.py build install" in the
52 </ul><p>The distribution includes a set of examples and regression tests for the
53 python bindings in the <code>python/tests</code> directory. Here are some
54 excepts from those tests:</p><h3>basic.py:</h3><p>This is a basic test of XSLT interfaces: loading a stylesheet and a
55 document, transforming the document and saving the result.</p><pre>import libxml2
58 styledoc = libxml2.parseFile("test.xsl")
59 style = libxslt.parseStylesheetDoc(styledoc)
60 doc = libxml2.parseFile("test.xml")
61 result = style.applyStylesheet(doc, None)
62 style.saveResultToFilename("foo", result, 0)
63 style.freeStylesheet()
65 result.freeDoc()</pre><p>The Python module is called libxslt, you will also need the libxml2 module
66 for the operations on XML trees. Let's have a look at the objects manipulated
67 in that example and how is the processing done:</p><ul><li><code>styledoc</code> : is a libxml2 document tree. It is obtained by
68 parsing the XML file "test.xsl" containing the stylesheet.</li>
69 <li><code>style</code> : this is a precompiled stylesheet ready to be used
70 by the following transformations (note the plural form, multiple
71 transformations can resuse the same stylesheet).</li>
72 <li><code>doc</code> : this is the document to apply the transformation to.
73 In this case it is simply generated by parsing it from a file but any
74 other processing is possible as long as one get a libxml2 Doc. Note that
75 HTML tree are suitable for XSLT processing in libxslt. This is actually
76 how this page is generated !</li>
77 <li><code>result</code> : this is a document generated by applying the
78 stylesheet to the document. Note that some of the stylesheet informations
79 may be related to the serialization of that document and as in this
80 example a specific saveResultToFilename() method of the stylesheet should
81 be used to save it to a file (in that case to "foo").</li>
82 </ul><p>Also note the need to explicitely deallocate documents with freeDoc()
83 except for the stylesheet document which is freed when its compiled form is
84 garbage collected.</p><h3>extfunc.py:</h3><p>This one is a far more complex test. It shows how to modify the behaviour
85 of an XSLT transformation by passing parameters and how to extend the XSLT
86 engine with functions defined in python:</p><pre>import libxml2
95 # Small check to verify the context is correcly accessed
98 pctxt = libxslt.xpathParserContext(_obj=ctx)
99 ctxt = pctxt.context()
100 tctxt = ctxt.transformContext()
101 nodeName = tctxt.insertNode().name
105 return string.upper(str)
107 libxslt.registerExtModuleFunction("foo", "http://example.com/foo", f)</pre><p>This code defines and register an extension function. Note that the
108 function can be bound to any name (foo) and how the binding is also
109 associated to a namespace name "http://example.com/foo". From an XSLT point
110 of view the function just returns an upper case version of the string passed
111 as a parameter. But the first part of the function also read some contextual
112 information from the current XSLT processing environement, in that case it
113 looks for the current insertion node in the resulting output (either the
114 resulting document or the Result Value Tree being generated), and saves it to
115 a global variable for checking that the access actually worked.</p><p>For more informations on the xpathParserContext and transformContext
116 objects check the <a href="internals.html">libray internals description</a>.
117 The pctxt is actually an object from a class derived from the
118 libxml2.xpathParserContext() with just a couple more properties including the
119 possibility to look up the XSLT transformation context from the XPath
120 context.</p><pre>styledoc = libxml2.parseDoc("""
121 <xsl:stylesheet version='1.0'
122 xmlns:xsl='http://www.w3.org/1999/XSL/Transform'
123 xmlns:foo='http://example.com/foo'
124 xsl:exclude-result-prefixes='foo'>
126 <xsl:param name='bar'>failure</xsl:param>
127 <xsl:template match='/'>
128 <article><xsl:value-of select='foo:foo($bar)'/></article>
129 </xsl:template>
130 </xsl:stylesheet>
131 """)</pre><p>Here is a simple example of how to read an XML document from a python
132 string with libxml2. Note how this stylesheet:</p><ul><li>Uses a global parameter <code>bar</code></li>
133 <li>Reference the extension function f</li>
134 <li>how the Namespace name "http://example.com/foo" has to be bound to a
136 <li>how that prefix is excluded from the output</li>
137 <li>how the function is called from the select</li>
138 </ul><pre>style = libxslt.parseStylesheetDoc(styledoc)
139 doc = libxml2.parseDoc("<doc/>")
140 result = style.applyStylesheet(doc, { "bar": "'success'" })
141 style.freeStylesheet()
142 doc.freeDoc()</pre><p>that part is identical, to the basic example except that the
143 transformation is passed a dictionnary of parameters. Note that the string
144 passed "success" had to be quoted, otherwise it is interpreted as an XPath
145 query for the childs of root named "success".</p><pre>root = result.children
146 if root.name != "article":
147 print "Unexpected root node name"
149 if root.content != "SUCCESS":
150 print "Unexpected root node content, extension function failed"
152 if nodeName != 'article':
153 print "The function callback failed to access its context"
156 result.freeDoc()</pre><p>That part just verifies that the transformation worked, that the parameter
157 got properly passed to the engine, that the function f() got called and that
158 it properly accessed the context to find the name of the insertion node.</p><h3>pyxsltproc.py:</h3><p>this module is a bit too long to be described there but it is basically a
159 rewrite of the xsltproc command line interface of libxslt in Python. It
160 provides nearly all the functionalities of xsltproc and can be used as a base
161 module to write Python customized XSLT processors. One of the thing to notice
162 are:</p><pre>libxml2.lineNumbersDefault(1)
163 libxml2.substituteEntitiesDefault(1)</pre><p>those two calls in the main() function are needed to force the libxml2
164 processor to generate DOM trees compliant with the XPath data model.</p><p><a href="bugs.html">Daniel Veillard</a></p></td></tr></table></td></tr></table></td></tr></table></td></tr></table></td></tr></table></body></html>