如何调用function外的局部变量？

Question

I was trying to call local variables outside far from a function that I made. I was playing with Tkinter in python. Here is the sample code. Is that possible to call variables outside function anywhere?

from tkinter import *
font1 = "Roboto 14"

window = Tk()
window.geometry("1200x800")
window.title("TEST")
canvas = Canvas(window, bg = "#FFFFFF", height = 800, width = 1200, bd = 0,
                highlightthickness = 0)
canvas.place(x = 0, y = 0)

def load_auto_button_output ():
    get_text_file = r"Links.txt"
    read_text_file =  open(get_text_file, 'r')

    intermediate = read_text_file.read()
    urlList = intermediate.split("\n")

    s1 = urlList[0]
    s2 = urlList[1]

    txt_box.insert(0.0,
        s1  + '\n' +
        s2  + '\n'
    )

def load_automatically_button ():
    load_auto_button = Button(window, text = 'Automatically Load', font = font1 ,
                              width = 25, bd = 1, highlightthickness = 0,
                              relief = "ridge", command = load_auto_button_output)
    load_auto_button.place(x = 540, y = 60)

load_automatically_button ()

txt_box = Text(window, bg = 'white', font = font1, height = 10, width = 70, bd = 3,
               relief = "flat", wrap=WORD)
txt_box.place(x = 370, y = 500)

window.resizable(False, False)
window.mainloop()

Here you can see I made a button command function name load_auto_button_output and I called all output inside text_box , via txt_box.insert .

Now, how do I call text_box.insert outside of that load_auto_button_output or how do I call s1 , s2 variables outside that function?

I have tried global but it's not working by my side

global s1, s2

then I had to return the function load_auto_button_output () , then it's automatically print values from the button without a click and nothing happen when I press the Automatically Load button.

Answer 1

You can't access the local variables of a function outside the function. Sometimes you can pass their values to other functions if you call any from the function were they are being defined, but that doesn't help in this case.

You said you tried using global variables and it didn't work — but it should have, so the code below show how to do it that way.

I've also modified your code so it follows the PEP 8 - Style Guide for Python Code guidelines to a large degree so to make it more readable.

Update

I've changed the code to show how one might use the global variables after their values are set in one function in another. It also better illustrates how event-driven programming works.

Specifically, there's is now another button whose command= option is a new function that puts the values stored in the global variables into the text box.

---

import tkinter as tk   # PEP 8 says to avoid 'import *'.
from tkinter.constants import *  # However this is OK.
import tkinter.messagebox as messagebox


FONT1 = 'Roboto 14'  # Global constant.
LINKS_FILE_PATH = r'Links.txt'

# Define global variables.
s1, s2 = None, None

window = tk.Tk()
window.geometry('1200x800')
window.title('Test')
canvas = tk.Canvas(window, bg='#FFFFFF', height=800, width=1200, bd=0,
                   highlightthickness=0)
canvas.place(x=0, y=0)

def load_links():
    """Load URLs from links file."""
    global s1, s2  # Declare global variables being assigned to.

    with open(LINKS_FILE_PATH, 'r') as read_text_file:
        urlList = read_text_file.read().splitlines()

    s1, s2 = urlList[:2]  # Assign first two links read to the global variables.

    messagebox.showinfo('Success!', 'URLs loaded from file')
    put_in_text_box_btn.config(state=NORMAL)  # Enable button.

def put_in_text_box():
    """Put current values of global variables s1 and s2 into text box."""
    txt_box.delete('1.0', END)  # Clear Text widget's contents.
    txt_box.insert(0.0, s1+'\n' + s2+'\n')  # Insert them into the Text widget.


load_links_btn = tk.Button(window, text='Load Links', font=FONT1, width=25, bd=1,
                           highlightthickness=0, relief='ridge', command=load_links)
load_links_btn.place(x=540, y=60)

put_in_text_box_btn = tk.Button(window, text='Put in text box', font=FONT1, width=25,
                                bd=1, highlightthickness=0, relief='ridge',
                                state=DISABLED, command=put_in_text_box)
put_in_text_box_btn.place(x=540, y=100)

quit_btn = tk.Button(window, text='Quit', font=FONT1, width=25, bd=1,
                     highlightthickness=0, relief='ridge', command=window.quit)
quit_btn.place(x=540, y=140)

txt_box = tk.Text(window, bg='white', font=FONT1, height=10, width=70, bd=3,
                  relief='flat', wrap=WORD)
txt_box.place(x=370, y=500)

window.resizable(False, False)
window.mainloop()