beremiz

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

2018-08-10, Andrey Skvortsov
a3ac46366b86
Parents 068ccc02f5f2
Children 70143c20d2c0
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():
:_'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))
[-------------------------------------------------------------]
1 files changed, 5 insertions(+), 0 deletions(-)
  • +5 -0
    xmlclass/xmlclass.py
    • --- a/xmlclass/xmlclass.py Fri Aug 10 15:58:40 2018 +0300
    +++ b/xmlclass/xmlclass.py Fri Aug 10 17:45:33 2018 +0300
    @@ -1162,6 +1162,7 @@
    classmembers["get%s" % elmtname] = generateGetMethod(elmtname)
    classmembers["_init_"] = generateInitMethod(self, classinfos)
    + classmembers["_tmp_initial_"] = None
    classmembers["StructurePattern"] = GetStructurePattern(classinfos)
    classmembers["getElementAttributes"] = generateGetElementAttributes(self, classinfos)
    classmembers["getElementInfos"] = generateGetElementInfos(self, classinfos)
    @@ -1581,6 +1582,10 @@
    if element["type"] != CHOICE:
    initial = GetElementInitialValue(factory, element)
    if initial is not None:
    + # FIXME: 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.
    + object.__setattr__(self, "_tmp_initial_", initial)
    map(self.append, initial)
    return initMethod