How to thread with tkinter in python3 using queue? - python-3.x

Question

I'm trying to thread definitions in tkinter using queue in specifically python3
I've had similar code in python2 work great using a similar method without queue but in python3 from what i've read tkinter doesn't allow for multithreading with gui. I found some examples that uses Queue process. They outline i'm suppose to create an Queue object, a new thread with access to that queue and check for input in the main thread
#!/usr/bin/python3
from tkinter import *
import time
import threading
import queue
import subprocess
def temp_sensor(queue_list):
warning = 0
while True:
var = "cat /sys/class/thermal/thermal_zone*/temp"
temp_control = subprocess.check_output([var], shell=True)
temp_length = len(temp_control)
temp_control = temp_control[35:]
temp_control = temp_control[:-4]
temp_control = int(temp_control)
degree_sign= u'\N{DEGREE SIGN}'
displayed_temp = "Tempature: " + str(temp_control) + degree_sign + "C"
if temp_control > 79:
warning = warning + 1
if warning == 3:
print ("Warning Core Tempature HOT!")
warning = 0
if temp_control > 90:
time.sleep(3)
print ("Warning EXTREMLY to HOT!!!")
queue_list.put(displayed_temp)
time.sleep(1)
class Gui(object):
def __init__(self, queue_list):
self.queue_list = queue_list
self.root = Tk()
self.root.geometry("485x100+750+475")
main_tempature_status = StringVar(self.root)
Ts = Entry(self.root, textvariable=main_tempature_status)
Ts.pack()
Ts.place(x=331, y=70, width=160, height=25)
Ts.config(state=DISABLED, disabledforeground="Black")
self.root.after(1000, self.read_queue)
def read_queue(self):
try:
temp = self.queue.get_nowait()
self.main_tempature_status.set(temp)
except queue_list.Empty:
pass
self.root.after(1000, self.read_queue)
if __name__ == "__main__":
queue_list = queue.Queue()
gui = Gui(queue_list)
t1 = threading.Thread(target=temp_sensor, args=(queue_list,))
t1.start()
gui.root.mainloop()
My desired result is to run a some of these definitions to do various tasks and display their variables in the tkinter entry using python3.
when i run my code it gives me the variable from the queue but it won't post to the GUI. please forgive my less then pythonic code.

Answer 1

Change you Gui class to this:
class Gui(object):
def __init__(self, queue_list):
self.queue_list = queue_list
self.root = Tk()
self.root.geometry("485x100+750+475")
self.main_tempature_status = StringVar(self.root)
self.Ts = Entry(self.root, textvariable=self.main_tempature_status)
self.Ts.pack()
self.Ts.place(x=331, y=70, width=160, height=25)
self.Ts.config(state=DISABLED, disabledforeground="Black")
self.root.after(1000, self.read_queue)
def read_queue(self):
try:
temp = self.queue_list.get_nowait()
self.Ts.config(state=NORMAL)
self.main_tempature_status.set(temp)
self.Ts.config(state=DISABLED)
except queue.Empty:
pass
self.root.after(1000, self.read_queue)
Explanation:
variable main_temperature_status is used in function read_queue as class variable, but not defined as class variable.
You cannot show the change in value of Entry widget if it is always disabled, so enabling it before value change in read_queue.