beremiz

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

2018-08-10, Andrey Skvortsov
a3ac46366b86
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))
[-------------------------------------------------------------]
<?xml version='1.0' encoding='utf-8'?>
<PyFile xmlns:xhtml="http://www.w3.org/1999/xhtml">
<variables>
<variable name="Test_Python_Var" type="INT" initial="4"/>
<variable name="Second_Python_Var" type="INT" initial="5"/>
</variables>
<globals>
<xhtml:p><![CDATA[
import time,sys,ctypes
Python_to_C_Call = PLCBinary.Python_to_C_Call
Python_to_C_Call.restype = ctypes.c_int
Python_to_C_Call.argtypes = [ctypes.c_int, ctypes.POINTER(ctypes.c_int)]
def MyPythonFunc(arg):
i = ctypes.c_int()
if(Python_to_C_Call(arg, i)):
res = i.value
print "toC:", arg, "from C:", res, "FBID:", FBID
else:
print "Failed Python_to_C_Call failed"
res = None
print "Python read PLC global :",PLCGlobals.Test_Python_Var
PLCGlobals.Second_Python_Var = 789
sys.stdout.flush()
return res
async_error_test_code = """
def badaboom():
tuple()[0]
import wx
def badaboomwx():
wx.CallAfter(badaboom)
from threading import Timer
a = Timer(3, badaboom)
a.start()
b = Timer(6, badaboomwx)
b.start()
"""
]]></xhtml:p>
</globals>
<init>
<xhtml:p><![CDATA[
global x, y
x = 2
y = 5
print "py_runtime init:", x, ",", y
]]></xhtml:p>
</init>
<cleanup>
<xhtml:p><![CDATA[
print "py_runtime cleanup"
]]></xhtml:p>
</cleanup>
<start>
<xhtml:p><![CDATA[
global x, y
print "py_runtime start", x * x + y * y
]]></xhtml:p>
</start>
<stop>
<xhtml:p><![CDATA[
print "py_runtime stop"
]]></xhtml:p>
</stop>
</PyFile>