使用 tkinter 在 python 中的函数中无法识别全局变量

Question

所以我对 python 很陌生，所以这可能是一个简单的问题，我只是不明白这里发生了什么。但本质上我有一个下拉菜单，允许您选择一个角色，然后显示相应的角色图像。它第一次工作正常，但问题是我试图在选择新图像后清除图像，并且不断收到错误消息“UnboundLocalError：无法访问与它不相关的局部变量‘imageAppear’”一个值”

这让我感到困惑，因为我将“imageAppear”设置为全局变量，所以我不明白为什么它认为它是局部变量。

目前此代码只会在旧图像下方显示新图像。

我已附上下面的代码，任何帮助将不胜感激

### MAIN WINDOW ###

# Using tkinter version 8.6
# Visit https://docs.python.org/3/library/tkinter.html for documentation
# Using pack as the LayoutManager, 

import tkinter as tk
import tkinter.ttk as ttk
from tkinter import *
from tkinter import filedialog
from PIL import Image, ImageTk
import pathlib
from pathlib import Path

def main():
    root = tk.Tk()
    root.geometry('1280x760')
    root.title("Slippi Stats")
    title = Label(root, text = "Slippi Stats", font = ('Helvetica 20 bold')).pack(pady = 20)
    
    # Create a File Explorer label
    global label_file_explorer
    label_file_explorer = Label(root, 
                                text = "File Explorer using Tkinter",
                                width = 100, height = 4)
    
    # Select Character
    characters = ["Mario", "Bowser", "Peach", "Yoshi", "Donkey Kong",
                  "Captain Falcon", "Fox", "Ness", "Ice Climbers",
                  "Kirby", "Samus", "Zelda", "Link", "Pikachu",
                  "Jigglypuff", "Dr. Mario", "Luigi", "Ganondorf",
                  "Falco", "Young Link", "Pichu", "Mewtwo",
                  "Mr. Game & Watch", "Marth", "Roy"]
    global selectedCharacter
    global label1
    label1 = Label(root, image = "")
    global imageAppear
    imageAppear = True
    selectedCharacter = tk.StringVar(master=root) #Always pass the 'master' keyword argument
    selectedCharacter.set("Mario")
    selectedCharacter.trace_add('write', characterImage)
    characterLabel = tk.Label(root, text="Select a character to train against")
    characterLabel.pack(pady=10)
    dropdown = tk.OptionMenu(root, selectedCharacter, *characters)
    dropdown.pack()
    
    button_explore = Button(root, 
                            text = "Browse Files",
                            command = browseFiles)
    label_file_explorer.pack(pady=10)
    button_explore.pack(pady=10)
    quitButton = tk.Button(text="Quit", command=root.destroy)
    quitButton.pack(pady = 100)
    root.mainloop()

def characterImage(*args):
    ##if imageAppear == True:
        ##clearImage()
    path = pathlib.Path(__file__).parent.resolve()
    path = path._str + "\\CharacterImages\\{}.jpg".format(selectedCharacter.get())
    # path = path.replace("\\\\","\\")
    path = Path(path)
    characterImage = Image.open(path)
    test = ImageTk.PhotoImage(characterImage)
    label1 = tk.Label(image=test)
    label1.image = test
    # Position image
    label1.pack()
    imageAppear = True

def clearImage():
    label1.config(image = "")

def browseFiles():
    filename = filedialog.askopenfilename(initialdir = "/",
                                          title = "Select a File",
                                          filetypes = (("Slippi Files",
                                                        "*.slp*"),
                                                       ("All files",
                                                        "*.*")))
    label_file_explorer.configure(text="File Opened: "+filename)
main()

imageAppear 检查已被注释掉，因为当前它甚至无法显示带有该检查的一张图像

附注我知道使用全局变量是不好的编码习惯，不需要因为使用它们而把我撕成碎片。

Answer 1

也许你应该尝试将这个应用程序变成面向对象的方法，这样你的全局就可以被“self”取代。 也许你的问题不是全局的，但它使代码有点混乱。