POULibrary.py
author Andrey Skvortsov <andrej.skvortzov@gmail.com>
Fri, 24 Aug 2018 13:41:43 +0300
changeset 2297 96ca6b056c55
parent 1917 d51d14719392
child 2645 d15a997859b1
child 2964 a7b11c9f468e
permissions -rw-r--r--
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():
<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


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, a Integrated Development Environment for
# programming IEC 61131-3 automates supporting plcopen standard and CanFestival.
#
# Copyright (C) 2007: Edouard TISSERANT and Laurent BESSARD
#
# See COPYING file for copyrights details.
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.


from __future__ import absolute_import
from weakref import ref


class POULibrary(object):
    def __init__(self, CTR, LibName, TypeStack):
        from PLCControler import PLCControler
        self.CTR = ref(CTR)
        self.LibName = LibName
        self.LibraryControler = PLCControler()
        self.LibraryControler.OpenXMLFile(self.GetLibraryPath())
        self.LibraryControler.ClearConfNodeTypes()
        self.LibraryControler.AddConfNodeTypesList(TypeStack)
        self.program = None

    def GetSTCode(self):
        if not self.program:
            self.program = self.LibraryControler.GenerateProgram()[0]+"\n"
        return self.program

    def GetName(self):
        return self.LibName

    def GetCTR(self):
        return self.CTR()

    def GetTypes(self):
        return {"name": self.GetName(), "types": self.LibraryControler.Project}

    def GetLibraryPath(self):
        raise Exception("Not implemented")

    def Generate_C(self, buildpath, varlist, IECCFLAGS):
        # Pure python or IEC libs doesn't produce C code
        return ((""), [], False), ""


def SimplePOULibraryFactory(path):
    class SimplePOULibrary(POULibrary):
        def GetLibraryPath(self):
            return path
    return SimplePOULibrary