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
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<PyFile>
<variables>
<variable name="WiiNunchuckStickX" type="INT"/>
<variable name="WiiNunchuckStickY" type="INT"/>
<variable name="WiiNunchuckAccX" type="INT"/>
<variable name="WiiNunchuckAccY" type="INT"/>
<variable name="WiiNunchuckAccZ" type="INT"/>
<variable name="WiiNunchuckButtons" type="WORD"/>
<variable name="WiiButtons" type="WORD"/>
</variables>
<globals>
<![CDATA[
import cwiid,commands,sys,re,os,time
wiimote = None
WIIMOTE_ADDR_MODEL = re.compile("((?:[0-9A-F]{2})(?::[0-9A-F]{2}){5})\s*Nintendo")
nunchuckzero = None
def Wiimote_cback(messages, time):
global nunchuckzero
state = dict(messages)
bts = state.get(cwiid.MESG_BTN, None)
if bts is not None:
PLCGlobals.WiiButtons = bts
nunchuck = state.get(cwiid.MESG_NUNCHUK, None)
if nunchuck is not None:
PLCGlobals.WiiNunchuckButtons = nunchuck['buttons']
X,Y = nunchuck['stick']
PLCGlobals.WiiNunchuckAccX = nunchuck['acc'][cwiid.X]
PLCGlobals.WiiNunchuckAccY = nunchuck['acc'][cwiid.Y]
PLCGlobals.WiiNunchuckAccZ = nunchuck['acc'][cwiid.Z]
if nunchuckzero is None:
nunchuckzero = X,Y
(PLCGlobals.WiiNunchuckStickX,
PLCGlobals.WiiNunchuckStickY) = X-nunchuckzero[0],Y-nunchuckzero[1]
def Connect_Wiimote(connected_callback):
global wiimote,nunchuckzero
mac_addr = ''
try:
mac_addr = file("wiimac.txt","rt").read()
except:
PLCObject.LogMessage("Wiimote MAC unknown, scanning bluetooth")
output = commands.getoutput("hcitool scan")
result = WIIMOTE_ADDR_MODEL.search(output)
if result is not None:
mac_addr = result.group(1)
PLCObject.LogMessage("Found Wiimote with MAC %s"%mac_addr)
file("wiimac.txt","wt").write(mac_addr)
# Connect to wiimote
if not mac_addr:
PLCObject.LogMessage("Connection to unknown Wiimote...")
wiimote = cwiid.Wiimote()
else:
PLCObject.LogMessage("Connection to Wiimote %s..."%mac_addr)
wiimote = cwiid.Wiimote(mac_addr)
if wiimote is not None:
nunchuckzero = None
wiimote.rpt_mode = cwiid.RPT_BTN | cwiid.RPT_EXT
# use the callback interface
wiimote.mesg_callback = Wiimote_cback
wiimote.enable(cwiid.FLAG_MESG_IFC)
connected_callback(mac_addr)
PLCObject.LogMessage("Wiimote %s Connected"%mac_addr)
else:
PLCObject.LogMessage("Wiimote %s not found"%mac_addr)
os.remove("wiimac.txt")
connected_callback(None)
def Disconnect_Wiimote():
global wiimote
if wiimote is not None:
wiimote.disable(cwiid.FLAG_MESG_IFC)
time.sleep(0.1)
wiimote.close()
wiimote = None
PLCObject.LogMessage("Wiimote disconnected")
]]>
</globals>
<init>
<![CDATA[
]]>
</init>
<cleanup>
<![CDATA[
Disconnect_Wiimote()
]]>
</cleanup>
<start>
<![CDATA[
]]>
</start>
<stop>
<![CDATA[
]]>
</stop>
</PyFile>