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Python Win32com Excel. Issue with python threading and com object handling

For some days I've been breaking my head over some issues I'm having with a Win32Com Excel object in python.
What I'm trying to do is very simple; get the sheet names from a workbook and write a value to the bottom of a column. The workbook is often opened by the users and needs to remain accessible/editable, hence I decided to use Win32Com. Any other suggestions to achieve the same are very welcome as well.
The base-code is quite straightforward:
class excelCOM():
def __init__(self, file):
self.xl = win32com.client.gencache.EnsureDispatch('Excel.Application')
self.wb = self.xl.Workbooks(os.path.basename(file))
def getSheets(self):
return [s.Name for s in self.wb.Sheets]
def dataToCell(self, sheet, column, string):
sht = self.wb.Sheets(sheet)
maxLastCell = sht.Range('{}{}'.format(column, 1048576))
lastCell = maxLastCell.End(win32com.client.constants.xlUp)
lastCell.Offset(2, 1).Value = string
Issues occur when integrated with the rest of the software. I've gone through lots of documentation and trying different things but I've been unable to get a reliable result. I'll try my best to summarize what I've tried and what the observations were.
When I create a single instance of this class and run the methods, everything works as expected.
if __name__ == '__main__':
xlWb = excelCOM(r"TestBook.xlsx")
print(xlWb.getSheets())
xlWb.dataToCell("Sheet1", 'B', 'All Good')
The information to write to the excel file comes from a logfile that is being written to by another (external) program. My software monitors the file and writes to excel whenever there is a new line added. All of this is handled by the 'processor'. The formatting for the text that's written to excel is user defined. Those formatting settings (and others) are imported to the processor from a pickled (settings) object (allowing the user to save settings (using a GUI) and run the processor without needing the GUI). As code (extremely simplified, just to get the idea across):
class processor():
def __init__(self, settings_object):
self.com_object = excelCOM(settings_object.excel_filepath)
self.file_monitor(settings_object.input_filepath)
self.file_monitor.start()
def dispatch():
# called whenever file_monitor registers a change to the file at input_filepath
last_line = self.get_last_line(input_filepath)
sheet, column, formatted_text = self.process(last_line)
self.com_object.dataToCell(sheet, column, formatted_text)
Now, when text is supposed to be written to the excel file by the processor, I get Exception in thread Thread-1: pywintypes.com_error: (-2147221008, 'CoInitialize has not been called.', None, None) at sht = self.wb.Sheets(sheet)
When I call CoInitialize() before sht = self.wb.Sheets(sheet) I get Exception in thread Thread-1: pywintypes.com_error: (-2147417842, 'The application called an interface that was marshalled for a different thread.', None, None). Calling CoInitialize() anywhere else in the code doesn't seem to do anything.
Adding the same code as in init solves the issue from point 3, but this seems very wrong to me. Mainly because I don't exactly know why it fixes the issue and what's going on in the background with com objects in windows.
def dataToCell(self, sheet, column, string):
pythoncom.CoInitialize() # point 3.
self.xl = win32com.client.gencache.EnsureDispatch('Excel.Application') # point 4.
self.wb = self.xl.Workbooks(os.path.basename(self.file)) # point 4.
sht = self.wb.Sheets(sheet)
maxLastCell = sht.Range('{}{}'.format(column, 1048576))
lastCell = maxLastCell.End(win32com.client.constants.xlUp)
lastCell.Offset(2, 1).Value = string
Now switching to the GUI. As mentioned earlier, the settings file for the processor is created with help from a GUI. It basically gives the functionally to build the settings_object. In the GUI I also have a 'run' button which directly calls processor(settings_object) in a seperate Thread. When I do this, I don't even need to add the additional lines as described in point 3 and 4. It runs perfectly with just the base-code.
I've gone through dozens of pages of documentation, StackOverflow topics, tutorials, blogs hidden in the dark corners of the web, Python Programming on Win32 but I simply can't wrap my head around what's going on. I consider myself a half-decent programmer for 'get the job done' applications but I don't have any education in computer science (or even programming in general), which is what I suspect I'm lacking at the moment.
I'm hoping someone can point me in the right direction for understanding this behavior and maybe give some advice on the proper way of implementing this functionality for my scenario.
Please let me know if you require any more information.
Best regards and many thanks in advance,
RiVer

Maya RuntimeError: OpenMaya.py (kInvalidParameter): Index not in valid Range

I am writing a python tool that will store attributes of the stereoscopic camera in a scene into a JSON file.
I use this code to get the selected plane with the attributes I need to store
import maya.OpenMaya as om
selected = om.MSelectionList()
om.MGlobal.getActiveSelectionList(selected)
obj = om.MObject()
selected.getDependNode(0,obj)
sel = om.MFnDependencyNode(obj).name()
if sel != "npl_Near_ZP":
cmds.confirmDialog(title= 'Error:', message = 'Error: Please Select the correct plane', button =['OK'])
else:
jsonCreate(sel)
It was working perfectly before but now when I try to the script, I get the following runtime error and I 've sort of hit a wall here cause I don't understand what the problem is
Error: RuntimeError: file S:\Maya_2018_DI\build\Release\runTime\Python\Lib\site-packages\maya\OpenMaya.py line 18296: (kInvalidParameter): Index not in valid range #
I m still new to Maya so any help will be greatly appreciated
update I restarted my computer and the script is now running as it should. Can anyone explain this behaviour in case it happens again

Python GTK get selected value from the treeview

I am working on a mini GUI project , I am currently struggling to figure out how to get selected value from the list and then return that value to the main function so that I can use that value in somewhere else . Can someone help me please !!!!
####
self.device_list_store = gtk.ListStore(str,str,str,str,str)
for device in self.get_dev_list():
self.device_list_store.append(list(device))
device_list_treeview = gtk.TreeView(self.device_list_store)
selected_row = device_list_treeview.get_selection()
selected_row.connect("changed",self.item_selected)
####
def item_selected(self,selection):
model,row = selection.get_selected()
if row is not None:
selected_device = model[row][0]
at the moment ,the item_selected function is not returning anything , I want to return selected_device back to the main function so I can use it in other functions as well .
EDIT: I've edited code above to remove formatting errors #jcoppens

As you can see in the documentation, the item_selected function is called with one parameter, tree_selection. But if you define the function inside a class, it requires the self parameter too, which is normally added automatically. In your (confusing) example, there is no class defined, so I suspect the problem is your program which is incomplete.
Also, I suspect you don't want device_list_treeview = gtk.T... in the for loop:
for device in self.get_dev_list():
self.device_list_store.append(list(device))
device_list_treeview = gtk.TreeView(self.device_list_store)
And I suspect you want selected_device = mod... indented below the if:
if row is not None:
selected_device = model[row][0]
Please convert your example in a complete program, and formatted correctly.
BTW: item_selected is not a good name for the signal handler. It is also called if the item is unselected (which is why the signal is called 'changed')!
And important: Even though you should first read the basic Python tutorials and Gtk tutorials, you should then consider using lazka's excellent reference for all the Python APIs. There's a link on the page to download it completely and have it at hand in your computer.

How to use TideSDK openFolderChooseDialog

I'm trying to use TideSDK and python tp get the user to select a folder from the hard drive. Everything works, but I have no idea how obtain which folder the user selected.
I can't seem to find documentation on what Ti.UI.UserWindow.openFolderChooseDialog returns and what kind of object the callback function uses. I just get errors that "window" in "onopen" in my code below is a None Type object when I try to print it out.
Is there any documentation on the proper use of the openFolderChooseDialog, what signature the callback needs to be and how to get the Folder/directory from the dialog?
My code:
def onopen(window):
Ti.App.stdout("------------------ Opening Dialog")
Ti.App.stdout(window)
def burndir():
try:
dir = Ti.UI.getCurrentWindow().openFolderChooserDialog(onopen)
Ti.App.stdout(dir)
except:
Ti.App.stderr("------ There was an error: ")
Ti.App.stderr(sys.exc_info()[0])
Ti.App.stderr(sys.exc_info()[1])
Ti.App.stderr(sys.exc_info()[2])
Any help is much appreciated

I found the answer in a Javascript Code example here:
https://github.com/appcelerator/titanium_developer/blob/master/Resources/perspectives/projects/js/projects.js#L1338
It appears that openFolderChooserDialog return nothing (a None object in Python). The callback function passes one argument which is a StaticBoundList (a Tuple object in Python) that contains all of the selected folders (in case of allowing multiple selections)
Here is the updated code:
def onopen(window):
if (len(window) > 0):
Ti.App.stdout("------------------ Opening Dialog")
Ti.App.stdout(window[0])
else:
Ti.App.stdout("------------------ Nothing Selected")
def burndir():
try:
Ti.UI.getCurrentWindow().openFolderChooserDialog(onopen)
except:
Ti.App.stderr("------ There was an error: ")
Ti.App.stderr(sys.exc_info()[0])
Ti.App.stderr(sys.exc_info()[1])
Ti.App.stderr(sys.exc_info()[2])
I hope this helps someone struggling to find the same documentation!

Assign string to QLineEdit with PySide/PyQt

I'm having a little bit of trouble assigning values to a QLineEdit. I've read the documentation and feel that the QLineEdit.SetText() command will be used at some point.
I've used Qt Designer to design a GUI for my software. On the main window (MainWindow.py, with an accompanying ui_MainWindow.py setup file), I have a LineEdit (lineEditScanBarcode) which has strong focus. I've managed to pull input from that LineEdit pretty well. What I'd like to do is this:
If the input in LineEditScanBarcode = x, then assign the name 'John Smith' to a secondary QLineEdit (lineEditUser) which has a zero focus policy. This is what I have so far:
def ScanBarcode(self):
barcode = self.lineEditScanBarcode.text()
self.lineEditScanBarcode.clear()
if barcode == '12345':
print("Welcome John")
self.lineEditUser.setText() = 'John'
else: print("Sorry, user not recognised.")
Upon running this, I get the following error:
Syntax Error: can't assign to function call
I've had a look at the above error, but I'm still unsure as to what's going on here. I still have no idea to open one window on top of another (this software package will have about 10 windows), but that's another story!
Is my logic here on track? I've never used Qt before, so my understanding of the intricacies involved is lacking to say the least.
Any input would be great!

As the comment states, the error is on this line:
self.lineEditUser.setText() = 'John'
You are attempting to assign the value 'John' to that functioncall (as the error states). If you review the documentation for QLineEdit in PyQT, you'll see that QLineEdit.setText() requires a string to be passed to it.
So, what you need to do instead is pass the value 'John' to the function like so:
self.lineEditUser.setText('John')
On another note your idea that your
software package will have about 10 windows
is definitely something that you want to reexamine. More windows, especially when undocked and floating independently will no doubt cause usability issues. I'd strongly recommend sharing your ideas over at UserExperience.SE.