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, 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
import wx
from controls.CustomToolTip import CustomToolTip, TOOLTIP_WAIT_PERIOD
# -------------------------------------------------------------------------------
# Tool Tip Producer class
# -------------------------------------------------------------------------------
class ToolTipProducer(object):
"""
Class that implements an element that generate Tool Tip
"""
def __init__(self, parent):
"""
Constructor
@param parent: Parent Viewer
"""
self.Parent = parent
self.ToolTip = None
self.ToolTipPos = None
# Timer for firing Tool tip display
self.ToolTipTimer = wx.Timer(self.Parent, -1)
self.Parent.Bind(wx.EVT_TIMER,
self.OnToolTipTimer,
self.ToolTipTimer)
def __del__(self):
"""
Destructor
"""
self.DestroyToolTip()
def OnToolTipTimer(self, event):
"""
Callback for Tool Tip firing timer Event
@param event: Tool tip text
"""
# Get Tool Tip text
value = self.GetToolTipValue()
if value is not None and self.ToolTipPos is not None:
# Create Tool Tip
self.ToolTip = CustomToolTip(self.Parent, value)
self.ToolTip.SetToolTipPosition(self.ToolTipPos)
self.ToolTip.Show()
def GetToolTipValue(self):
"""
Return tool tip text
Have to be overridden by inherited classes
@return: Tool tip text (None if not overridden)
"""
return None
def DisplayToolTip(self, pos):
"""
Display Tool tip
@param pos: Tool tip position
"""
# Destroy current displayed Tool tip
self.DestroyToolTip()
# Save Tool Tip position
self.ToolTipPos = pos
# Start Tool tip firing timer
self.ToolTipTimer.Start(
int(TOOLTIP_WAIT_PERIOD * 1000),
oneShot=True)
def SetToolTipText(self, text):
"""
Set current Tool tip text
@param text: Tool tip Text
"""
if self.ToolTip is not None:
self.ToolTip.SetTip(text)
def DestroyToolTip(self):
"""
Destroy current displayed Tool Tip
"""
# Stop Tool tip firing timer
self.ToolTipTimer.Stop()
self.ToolTipPos = None
# Destroy Tool Tip
if self.ToolTip is not None:
self.ToolTip.Destroy()
self.ToolTip = None