beremiz

Proper fix for error 'object has no attribute 'getSlave' in EtherCAT extension

2018-08-24, Andrey Skvortsov
96ca6b056c55
Proper 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


Revert commit "Dirty fix for error '_object_has_no_attribute_'getSlave' in EtherCAT extension"
[a3ac46366b86a0b237dac93be6b2281ac70b98a8].

The problem was that XML elements (proxy object) in some cases were created using custom XML
classes constructors and lxml.etree.Element() call and live python
patching. This causes that lxml backend doesn't know that custom python class
should be used for these XML elements.
Proxy object can be move/deleted and recreated by lxml
backend at any point in time or this can be done in python by copy/deepcopy operations.
If this happens, then newly created
proxy elements are using default class lxml.etree._Element. And all
custom functionality is lost.

All created XML elements should be always created through corresponding
parser and class lookup callback done by lxml backend.
It's described in more details in lxml documentation:
https://lxml.de/element_classes.html
#!/usr/bin/env python
# -*- coding: utf-8 -*-
# This file is part of Beremiz.
# See COPYING file for copyrights details.
from __future__ import absolute_import
from plcopen.XSLTModelQuery import XSLTModelQuery, _StringValue, _BoolValue, _translate_args
from plcopen.types_enums import CLASS_TYPES, POU_TYPES, VAR_CLASS_INFOS
def class_extraction(value):
class_type = CLASS_TYPES.get(value)
if class_type is not None:
return class_type
pou_type = POU_TYPES.get(value)
if pou_type is not None:
return pou_type
var_type = VAR_CLASS_INFOS.get(value)
if var_type is not None:
return var_type[1]
return None
class _VariablesTreeItemInfos(object):
__slots__ = ["name", "var_class", "type", "edit", "debug", "variables"]
def __init__(self, *args):
for attr, value in zip(self.__slots__, args):
setattr(self, attr, value if value is not None else "")
def copy(self):
return _VariablesTreeItemInfos(*[getattr(self, attr) for attr in self.__slots__])
class VariablesTreeInfosFactory(object):
def __init__(self):
self.Root = None
def GetRoot(self):
return self.Root
def SetRoot(self, context, *args):
self.Root = _VariablesTreeItemInfos(
*([''] + _translate_args(
[class_extraction, _StringValue] + [_BoolValue] * 2,
args) + [[]]))
def AddVariable(self, context, *args):
if self.Root is not None:
self.Root.variables.append(_VariablesTreeItemInfos(
*(_translate_args(
[_StringValue, class_extraction, _StringValue] +
[_BoolValue] * 2, args) + [[]])))
class POUVariablesCollector(XSLTModelQuery):
def __init__(self, controller):
XSLTModelQuery.__init__(self,
controller,
"pou_variables.xslt",
[(name, self.FactoryCaller(name))
for name in ["SetRoot", "AddVariable"]])
def FactoryCaller(self, funcname):
def CallFactory(*args):
return getattr(self.factory, funcname)(*args)
return CallFactory
def Collect(self, root, debug):
self.factory = VariablesTreeInfosFactory()
self._process_xslt(root, debug)
res = self.factory.GetRoot()
self.factory = None
return res