Dirty fix for error '_object_has_no_attribute_'getSlave' in EtherCAT extension

traceback:
File "/home/developer/WorkData/PLC/beremiz/beremiz/IDEFrame.py", line 1433, in OnPouSelectedChanged
window.RefreshView()
File "/home/developer/WorkData/PLC/beremiz/beremiz/etherlab/ConfigEditor.py", line 837, in RefreshView
self.RefreshProcessVariables()
File "/home/developer/WorkData/PLC/beremiz/beremiz/etherlab/ConfigEditor.py", line 886, in RefreshProcessVariables
slaves = self.Controler.GetSlaves(**self.CurrentNodesFilter)
File "/home/developer/WorkData/PLC/beremiz/beremiz/etherlab/EthercatMaster.py", line 341, in GetSlaves
for slave in self.Config.getConfig().getSlave():
<type 'exceptions.AttributeError'>:_'lxml.etree._Element'_object_has_no_attribute_'getSlave'

Steps to reproduce problem:

- Add new EtherCAT master
- Add new EthercatNode to the master
- double click on


this is looks like dirty hack to fix strange problem with initial[0]
changing its type after returning from _init_ method to lxml.etree._Element
As a result all methods generated by class factory are lost.

For example, in function initMethod initial[0].__class__ points to
xmlclass.xmlclass.Config. After map(self.append, initial)
self.Config.__class__ is 'xmlclass.xmlclass.Config' as well.
But after returning from initMethod (_init) in CreateElement
self.Config.__class__ has changed to lxml.etree._Element.


I've noticed similar behavior if copy/deepcopy is used for any child
of etree.ElementBase. See simple example below.
[-------------------------------------------------------------]
#!/usr/bin/python

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))
[-------------------------------------------------------------]

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#!/usr/bin/env python

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# -*- coding: utf-8 -*-

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# This file is part of Beremiz.

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# See COPYING file for copyrights details.

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from __future__ import absolute_import

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import os

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from lxml import etree

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import util.paths as paths

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from plcopen.structures import StdBlckLibs

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ScriptDirectory = paths.AbsDir(__file__)

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class XSLTModelQuery(object):

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    """ a class to handle XSLT queries on project and libs """

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    def __init__(self, controller, xsltpath, ext=None):

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        # arbitrary set debug to false, updated later

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        self.debug = False

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        # merge xslt extensions for library access to query specific ones

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        xsltext = [

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            ("GetProject", lambda *_ignored:

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             [controller.GetProject(self.debug)]),

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            ("GetStdLibs", lambda *_ignored:

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             [lib for lib in StdBlckLibs.values()]),

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            ("GetExtensions", lambda *_ignored:

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             [ctn["types"] for ctn in controller.ConfNodeTypes])

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        ]

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        if ext is not None:

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            xsltext.extend(ext)

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        # parse and compile. "beremiz" arbitrary namespace for extensions

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        self.xslt = etree.XSLT(

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            etree.parse(

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                os.path.join(ScriptDirectory, xsltpath),

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                etree.XMLParser()),

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            extensions={("beremiz", name): call for name, call in xsltext})

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    def _process_xslt(self, root, debug, **kwargs):

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        self.debug = debug

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        res = self.xslt(root, **{k: etree.XSLT.strparam(v) for k, v in kwargs.iteritems()})

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        # print(self.xslt.error_log)

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        return res

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# -------------------------------------------------------------------------------

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#           Helpers functions for translating list of arguments

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#                       from xslt to valid arguments

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# -------------------------------------------------------------------------------

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def _StringValue(x):

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    return x

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def _BoolValue(x):

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    return x in ["true", "0"]

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def _translate_args(translations, args):

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    return [translate(arg[0]) if len(arg) > 0 else None

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            for translate, arg in

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            zip(translations, args)]