[lxml-dev] how to inherit from ElementBase?

[TP]

Hi everybody,

For my application, I try to inherit the ElementBase class of lxml.
I have read the following page:

http://codespeak.net/lxml/dev/api/lxml.etree.ElementBase-class.html

"Class ElementBase: The public Element class. All custom Element classes
must inherit from this one. To create an Element, use the Element()
factory."

So I have tried to define a new class deriving from ET.ElementBase, and set
the factory (__metaclass__) to ET.Element. You will find my code below. I
obtain:

$ p test_element_factory.py
Traceback (most recent call last):
  File "test_element_factory.py", line 3, in <module>
    class NewElement( ET.ElementBase ):
  File "etree.pyx", line 1844, in etree.Element
  File "apihelpers.pxi", line 129, in etree._makeElement
  File "apihelpers.pxi", line 116, in etree._makeElement
  File "etree.pyx", line 362, in etree._Document._setNodeNamespaces
  File "apihelpers.pxi", line 651, in etree._utf8
TypeError: Argument must be string or unicode.

What is the problem?
Thanks in advance,

Julien

##############################
import lxml.etree as ET

class NewElement( ET.ElementBase ):

    __metaclass__ = ET.Element

    def _init( self
            , *args
            , **kwargs ):

        super( NewElement, self ).__init__( self
                , *args
                , **kwargs )

a = NewElement( "root" )
print a
##############################


-- 
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9&1+,\'Z4(55l4('])"

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