As of version 1.1, lxml.etree provides a public C-API. This allows external C extensions to efficiently access public functions and classes of lxml, without going through the Python API.
# My Cython extension # import the public functions and classes of lxml.etree cimport etreepublic as cetree # import the lxml.etree module in Python cdef object etree from lxml import etree # initialize the access to the C-API of lxml.etree cetree.import_lxml__etree()
From this line on, you can access all public functions of lxml.etree from the cetree namespace like this:
# build a tag name from namespace and element name py_tag = cetree.namespacedNameFromNsName("http://some/url", "myelement")
Public lxml classes are easily subclassed. For example, to implement and set a new default element class, you can write Cython code like the following:
from etreepublic cimport ElementBase cdef class NewElementClass(ElementBase): def set_value(self, myval): self.set("my_attribute", myval) etree.set_element_class_lookup( etree.DefaultElementClassLookup(element=NewElementClass))
If you really feel like it, you can also interface with lxml.etree straight from C code. All you have to do is include the header file for the public API, import the lxml.etree module and then call the import function:
/* My C extension */ /* common includes */ #include "Python.h" #include "stdio.h" #include "string.h" #include "stdarg.h" #include "libxml/xmlversion.h" #include "libxml/encoding.h" #include "libxml/hash.h" #include "libxml/tree.h" #include "libxml/xmlIO.h" #include "libxml/xmlsave.h" #include "libxml/globals.h" #include "libxml/xmlstring.h" /* lxml.etree specific includes */ #include "lxml-version.h" #include "etree_defs.h" #include "etree.h" /* setup code */ import_lxml__etree()
Note that including etree.h does not automatically include the header files it requires. Note also that the above list of common includes may not be sufficient.