The following is a simplified example of the behaviour we’re seeing the Sunburnt library, which uses lxml:

 

Python 2.4.3 (#1, Sep 21 2011, 19:55:41)

[GCC 4.1.2 20080704 (Red Hat 4.1.2-51)] on linux2

Type "help", "copyright", "credits" or "license" for more information.

>>> import lxml.etree

>>> from lxml.builder import E

>>>

>>> class Foo(object):

...     QUERY = E.query

...    

...     def test(self, q):

...         return self.QUERY(q)

...

>>> foo = Foo()

>>> bar = foo.test('a')

Traceback (most recent call last):

  File "<stdin>", line 1, in ?

  File "<stdin>", line 5, in test

  File "/opt/define/lib/python2.4/site-packages/lxml-2.2.7_r0-py2.4-linux-x86_64.egg/lxml/builder.py", line 47, in <lambda>

    return lambda *args, **kwargs: func(tag, *args, **kwargs)

  File "/opt/define/lib/python2.4/site-packages/lxml-2.2.7_r0-py2.4-linux-x86_64.egg/lxml/builder.py", line 220, in __call__

    raise TypeError("bad argument type: %r" % item)

TypeError: bad argument type: <__main__.Foo object at 0x2b1a8a79ee10>

 

Python 2.7, lxml 2.7.7

>>> import lxml.etree

>>> from lxml.builder import E

>>>

>>> class Foo(object):

...     QUERY = E.query

...    

...     def test(self, q):

...         return self.QUERY(q)

...

>>> foo = Foo()

>>> bar = foo.test('a')

>>> print lxml.etree.tostring(bar)

<query>a</query>

 

I’m looking for guidance on whether the exception in Python 2.4 is due to a bug in lxml, incorrect usage in binding E.query to a class attribute, or perhaps an error on our part when building lxml on Redhat.

 

The Sunburnt code in which this occurred is SoldrDelete.delete_queries() https://github.com/tow/sunburnt/blob/master/sunburnt/schema.py#L617

 

With thanks, Alex