python: Appending a value to a list outside the class, function with append also outside the class, but function is called within a class

Question

I am very new to python and I've been trying to do this code where i use a tkinter button command to run a function, it works but the append() is not executing, meaning it does not append to the list.

The list and the function containing the append is outside the class and is then classed within a class through the use of tkinter button command

I've tried putting the function inside the class, it works but the append is not adding into the list again.

import tkinter as tk
from threading import Thread
from queue import Queue
import time
from tkinter import messagebox

LARGE_FONT = ("Verdana", 12)


Receipt = []
prices = []
job_queue = Queue()
Orders = []

class SushiMenuApp(tk.Tk):

    def __init__(self, *args, **kwargs):
        tk.Tk.__init__(self, *args, **kwargs)
        container = tk.Frame(self)

        container.pack(side="top", fill="both", expand=True)

        container.grid_rowconfigure(0, weight=1)
        container.grid_columnconfigure(0, weight=1)

        self.frames = {}

        for F in (OrderPage, ReceiptPage):
            frame = F(container, self)

            self.frames[F] = frame

            frame.grid(row=0, column=0, sticky="nsew")

        self.show_frame(OrderPage)

    def show_frame(self, cont):
        frame = self.frames[cont]
        frame.tkraise()

def sushichef(job_queue):
    while True:
        a = job_queue.get()
        if a is None:
            print("There are no more orders")
            break        
        messagebox.showinfo("Message", "Sushi Chef started doing you order")
        time.sleep(a)
        print("Your order will be coming to you now")
        job_queue.task_done()


class OrderPage(tk.Frame):

    def __init__(self, parent, controller):
        tk.Frame.__init__(self, parent)
        label = tk.Label(self, text="Sushi Selections", font=LARGE_FONT)
        label.grid(row=0, column=0, columnspan=4)



        checkout = tk.Button(self, text="Check Out", command=lambda:controller.show_frame(ReceiptPage))
    checkout.grid(row=0, column=4)

        for _ in range(4):  # 4 Sushi Chefs
            thread = Thread(target=sushichef, args=(job_queue,))
            thread.start()
            Orders.append(thread)

        shrimptempura = tk.Button(self, text="Shrimp Tempura",
                              command= staction)
        shrimptempura.grid(row=1, column=0)

def staction():
    for item in [60]:
        job_queue.put(item)
    prices.append(69)
    Receipt.append("Shrimp Tempura")

class ReceiptPage(tk.Frame):

    def __init__(self, parent, controller):

        tk.Frame.__init__(self, parent)
        label = tk.Label(self, text="Receipt", font=LARGE_FONT)
        label.grid(row=0, columnspan=4, sticky="nsew")

        fullreceipt= tk.Label(self, text='\n'.join(map(str, Receipt)))
        fullreceipt.grid(row=1, columnspan=4, rowspan=48)
        sumprice= tk.Label(self, text=sum(prices))
        sumprice.grid(row=49, column=1, columnspan=2)

app = SushiMenuApp()
app.mainloop()

I was expecting the output to add the value within the prices.append() and the string within the receipt.append() together along with the job_queue,

expected would be that in the receipt page it would look something like this

Receipt
Shrimp Tempura
70

but the output is that only the job_queue is what i can see as working because the message box was working which was the effect of the job_queue but in the ReceiptPage it would only show

Receipt

furas · Answer 1 · 2019-07-13T10:21:14.277

Frame ReceiptPage is create at start, before you press any button or even see window, so Labels get information from empty lists. You have to add function which updates Labels in ReceiptPage and execute it when you pless Check Out

You will have to also use self. for labels so you have access to labels in other functions.

ReceiptPage has function which update labels. Labels uses self.

class ReceiptPage(tk.Frame):

    def update_labels(self):
        self.fullreceipt['text'] = '\n'.join(map(str, Receipt))
        self.sumprice['text'] = sum(prices)

OrderPage has function which change page and run update_labels. controler also uses self.

def show_check_out(self):
    self.controller.show_frame(ReceiptPage)
    self.controller.frames[ReceiptPage].update_labels()

and button executes this function

    checkout = tk.Button(self, text="Check Out", command=self.show_check_out)

Full code:

import tkinter as tk
from threading import Thread
from queue import Queue
import time
from tkinter import messagebox

LARGE_FONT = ("Verdana", 12)


Receipt = []
prices = []
job_queue = Queue()
Orders = []

class SushiMenuApp(tk.Tk):

    def __init__(self, *args, **kwargs):
        tk.Tk.__init__(self, *args, **kwargs)
        container = tk.Frame(self)

        container.pack(side="top", fill="both", expand=True)

        container.grid_rowconfigure(0, weight=1)
        container.grid_columnconfigure(0, weight=1)

        self.frames = {}

        for F in (OrderPage, ReceiptPage):
            frame = F(container, self)

            self.frames[F] = frame

            frame.grid(row=0, column=0, sticky="nsew")

        self.show_frame(OrderPage)

    def show_frame(self, cont):
        frame = self.frames[cont]
        frame.tkraise()

def sushichef(job_queue):
    while True:
        a = job_queue.get()
        if a is None:
            print("There are no more orders")
            break        
        messagebox.showinfo("Message", "Sushi Chef started doing you order")
        time.sleep(a)
        print("Your order will be coming to you now")
        job_queue.task_done()


class OrderPage(tk.Frame):

    def __init__(self, parent, controller):
        tk.Frame.__init__(self, parent)
        self.controller = controller

        label = tk.Label(self, text="Sushi Selections", font=LARGE_FONT)
        label.grid(row=0, column=0, columnspan=4)

        checkout = tk.Button(self, text="Check Out", command=self.show_check_out)
        checkout.grid(row=0, column=4)

        for _ in range(4):  # 4 Sushi Chefs
            thread = Thread(target=sushichef, args=(job_queue,))
            thread.start()
            Orders.append(thread)

        shrimptempura = tk.Button(self, text="Shrimp Tempura", command=staction)
        shrimptempura.grid(row=1, column=0)

    def show_check_out(self):
        self.controller.show_frame(ReceiptPage)
        self.controller.frames[ReceiptPage].update_labels()

def staction():
    for item in [6]:
        job_queue.put(item)
    prices.append(69)
    Receipt.append("Shrimp Tempura")

class ReceiptPage(tk.Frame):

    def __init__(self, parent, controller):

        tk.Frame.__init__(self, parent)

        self.label = tk.Label(self, text="Receipt", font=LARGE_FONT)
        self.label.grid(row=0, columnspan=4, sticky="nsew")

        self.fullreceipt= tk.Label(self, text='\n'.join(map(str, Receipt)))
        self.fullreceipt.grid(row=1, columnspan=4, rowspan=48)

        self.sumprice= tk.Label(self, text=sum(prices))
        self.sumprice.grid(row=49, column=1, columnspan=2)

    def update_labels(self):
        self.fullreceipt['text'] = '\n'.join(map(str, Receipt))
        self.sumprice['text'] = sum(prices)


app = SushiMenuApp()
app.mainloop()

To make it more universal you can create in every frame function update_frame (even empty function) and then you can execute it in show_frame

def show_frame(self, cont):
    frame = self.frames[cont]
    frame.tkraise()
    frame.update_frame()

Don't use name update() because it is used by tkinter.

python: Appending a value to a list outside the class, function with append also outside the class, but function is called within a class

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