[lxml] copy ElementBase subclass

Aug. 8, 2018

      Hi,

copy/deepcopy copies all xml content, but information about added
methods is lost.

Here is small example:
[------------ subclass.py-----------------]
from __future__ import print_function
from lxml import etree
import copy

class DefaultElementClass(etree.ElementBase):
    def getLocalTag(self):
        return etree.QName(self.tag).localname

def printInformation(x):
    print(x, x.__class__, "getLocalTag" in dir(x))

a = DefaultElementClass()
printInformation(a)

#
printInformation(copy.copy(a))
printInformation(copy.deepcopy(a))
[-----------------------------------------]

Output:
<Element DefaultElementClass at 0x7f13d15416d8> <class '__main__.DefaultElementClass'> True
<Element DefaultElementClass at 0x7f13d1652d88> <type 'lxml.etree._Element'> False
<Element DefaultElementClass at 0x7f13d1652d88> <type 'lxml.etree._Element'> False

Expected output:
<Element DefaultElementClass at 0x7f13d15416d8> <class '__main__.DefaultElementClass'> True
<Element DefaultElementClass at 0x7f13d15416d8> <class '__main__.DefaultElementClass'> True
<Element DefaultElementClass at 0x7f13d15416d8> <class '__main__.DefaultElementClass'> True

How create copy of the element and keep all methods
from subclass?

python-lxml:amd64    4.2.3-1

-- 
Best regards,
Andrey Skvortsov