How do I set up Tkinter in python to display and update a variable?

Question

I am trying to update a variable every 2.5 seconds, but somehow it will not display on Tkinter.

I wrote all of the code except Tkinter related things as I have very little knowledge in that area. I manipulated code I got from a website giving an example for using Tkinter.

Here is the code:

import threading
from tkinter import *

def onclick():
   pass


its1_c = 0    # first upgrade amount
its2_c = 0    # second upgrade amount
ITS1 = its1_c * 30 # amount of first upgrade owned x multiplier to money
ITS2 = its2_c * 70 # amount of second upgrade owned x multiplier to money

cashflow = 0
balance = 100
def moneygain():
    global cashflow
    global balance
    global text
    text = balance
    cashflow = balance
    threading.Timer(2.5, moneygain).start()
    cashflow = cashflow + 10
    cashflow = cashflow + ITS2
    cashflow = cashflow + ITS1
    balance = cashflow
    print("Balance: " + str(balance))
    text.insert(INSERT, balance)
    root = Tk()
    text = Text(root)
    text.insert(INSERT, balance)
    text.pack()

    text.tag_add("here", "1.0", "1.4")
    text.tag_add("start", "1.8", "1.13")
    text.tag_config("here", background="yellow", foreground="blue")
    text.tag_config("start", background="black", foreground="green")
    root.mainloop()  

moneygain()

When I try to display "balance" it does not update. Instead it throws out this error:

Exception in thread Thread-2:
Traceback (most recent call last):

File "D:\Python34\lib\threading.py", line 911, in _bootstrap_inner
    self.run()
  File "D:\Python34\lib\threading.py", line 1177, in run
    self.function(*self.args, **self.kwargs)
  File "D:/Python34/menugui.py", line 27, in moneygain
    text.insert(INSERT, balance)
AttributeError: 'int' object has no attribute 'insert'

How can I display balance on the Tkinter window?

The "print("Balance " + str(balance))" is from when I was testing the function but forgot to remove it — Samuelf80, May 30 '16 at 08:40

score 1 · Accepted Answer · edited Jun 04 '16 at 13:12

To solve your problem of getting your balance variable to update on tkinter here is my solution:

  from Tkinter import *

  root = Tk()
  moneyShown = Label(root, font=('times', 20, 'bold')) #use a Label widget, not Text
  moneyShown.pack(fill=BOTH, expand=1)
  def onclick():
     pass


  its1_c = 0    # first upgrade amount
  its2_c = 0    # second upgrade amount
  ITS1 = its1_c * 30 # amount of first upgrade owned x multiplier to money
  ITS2 = its2_c * 70 # amount of second upgrade owned x multiplier to money

  cashflow = 0
  balance = 100
  def moneygain():
      global cashflow
      global balance
      global text
      text = balance
      cashflow = balance

      cashflow = cashflow + 10
      cashflow = cashflow + ITS2
      cashflow = cashflow + ITS1
      balance = cashflow
      print("Balance: " + str(balance))

      moneyShown.configure(text="Balance: "+str(balance)) #changes the label's text
      moneyShown.after(2500, moneygain) #tkinter's threading (look more into how this works)
  moneygain()
  root.mainloop()

Tkinter really doesnt like old fashioned threading, and works much better using the function .after() as used on the last line of moneygain()

Also I took creative liberty and switched your Text widget to a Label. As you said you are new to the language, I'm pretty sure a Label is much more appropriate than a Text in this situation (at least for this problem fix!).

Another suggestion: when you are going to call a function multiple times (as we are calling moneygain multiple times) its a good practice not to create widgets in these functions. When I was testing your code, it infinitely made new Text widgets as it was called over and over (again, probably not what you wanted).

Tkinter is very tricky to learn at first but once you learn it, it is really fun! Good luck on your project!

Cheers mate, you fixed it all! Very thorough answer and very helpful, than you ever so much. My next improvement is to add buttons to alter the values of its1_c and its2_c — Samuelf80, May 30 '16 at 09:38
@Samuelf80 You're Welcome! If you are ever looking for quick help on the syntax of certain widgets, definitely give http://effbot.org/tkinterbook/ a look. Those guys have helped me learn Tkinter more than I can remember. — Gunner Stone, May 30 '16 at 09:50
The comment "tkinter's threading" in the code isn't correct. This has nothing to do with threads. You're merely adding something to a queue when you call `after`. — Bryan Oakley, May 30 '16 at 12:28

How do I set up Tkinter in python to display and update a variable?

1 Answers1