Hi! I am playing around with custom element classes, and encountered the following problem: when using xpath to find a specific (custom) element, the element that is returned is not an instance of the custom element class. Instead, it is an instance of the standard Element class. This causes any call to a method of the custom class to fail with an AttributeError. See (simplified but working) code below. I have just started using lxml, so I am not very experienced; however, I could not find an answer to my question in the online tutorial and reference material, while google did not give any clues either. Can anyone help me with this? Is the class lookup method implemented correctly in my code? It seems to work when the custom elements are generated... Thanks! Roel ### Start of code ### from lxml import etree as ET class BliepElement(ET.ElementBase): TAG = 'bliep' def test(self): print "Bliep is testing!" class BlupElement(ET.ElementBase): TAG = 'blup' def test(self): print "Blup is testing!" def addBliep(self): x = self.xpath('//bliep') if not x: b = BliepElement() self.insert(0, b) def getBliep(self): x = self.xpath('//bliep') if not x: return None else: return x[0] class MyLookup(ET.CustomElementClassLookup): def lookup(self, nodetype, document, namespace, name): if name=='bliep': return BliepElement if name=='blup': return BlubElement parser = ET.XMLParser() parser.set_element_class_lookup(MyLookup()) ET.Element = parser.makeelement b1 = BlupElement() b1.addBliep() b2 = b1.getBliep() print ET.tostring(b1) print type(b1).mro() print type(b2).mro(b2.test() ### End of code ### Output when run in terminal: $ python test.py <blub><bliep/></blub> [<class '__main__.BlupElement'>, <type 'lxml.etree.ElementBase'>, <type 'lxml.etree._Element'>, <type 'object'>] [<type 'lxml.etree._Element'>, <type 'object'>] Traceback (most recent call last): File "test.py", line 54, in <module> b2.test() AttributeError: 'lxml.etree._Element' object has no attribute 'test'