Question

我目前正在使用python开发自动点唱机/音乐播放器。为了使代码更有条理，我将其分为特定的类。一些外部函数需要访问类变量并对其进行更新。但是，该程序引发以下错误：

 File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/tkinter/__init__.py", line 1702, in __call__
    return self.func(*args)
  File "jukeboxDraft.py", line 77, in nextSong
    constructGUI.index += 1
NameError: name 'constructGUI' is not defined

访问类变量的类和函数在以下代码块中：

import os
import pygame
from tkinter.filedialog import askdirectory
from tkinter import *
import eyed3

class JukeboxContent:
    def __init__(self):
        listOfSongs = []
        songTitles = []
        directory = askdirectory()
        self.listOfSongs = listOfSongs
        self.songTitles = songTitles
        self.directoryAsk = directory
        self.Error_NoMP3s = "No \".mp3\" files found."

    def directoryChooser(self):
        self.directoryAsk
        os.chdir(self.directoryAsk)

        for files in os.listdir(self.directoryAsk):
            if files.endswith(".mp3"):
                realdir = os.path.realpath(files)
                audioTag = eyed3.load(realdir)
                self.songTitles.append(audioTag.tag.title)
                self.listOfSongs.append(files)
                #print(files)

        pygame.mixer.init()
        pygame.mixer.music.load(self.listOfSongs[0])
        pygame.mixer.music.play()



class JukeboxGUI(JukeboxContent):
    index = 0
    def __init__(self, window):
        JukeboxContent.__init__(self)
        self.back = Frame(master = window, width=500, height=500,  bg='pink')
        self.label = Label(window, text = "Jukebox")
        self.listBox = Listbox(window)
        self.nextButton = Button(window, text = "Next Song")
        self.previousButton = Button(window, text = "Previous Song")
        self.stopButton = Button(window, text = "Stop")
        self.labelVar = StringVar()
        self.songLabel= Label(window, textvariable = self.labelVar, width = 50)

    def constructButtons(self):
        self.back.pack()
        self.label.pack()
        self.listBox.pack()
        for items in self.listOfSongs:
            self.listBox.insert(END, items)
        self.nextButton.pack()
        self.previousButton.pack()
        self.stopButton.pack()

    def updateLabel(self):
        self.labelVar.set(self.songTitles[self.index])

#-------------------------JUKEBOX FUNCTIONS-------------------------------------


def main():
    window = Tk()
    window.title("Jukebox")
    initiateJukebox = JukeboxContent()
    initiateJukebox.directoryChooser()
    constructGUI = JukeboxGUI(window)
    constructGUI.constructButtons()
    constructGUI.nextButton.bind("<Button-1>", nextSong)
    constructGUI.previousButton.bind("<Button-1>", previousSong)
    constructGUI.stopButton.bind("<Button-1>", stopSong)
    window.mainloop()

def nextSong(event):
    constructGUI.index += 1
    pygame.mixer.music.load(initiateJukebox.listOfSongs[constructGUI.index])
    pygame.mixer.music.play()
    constructGUI.updateLabel()

def previousSong(event):
    constructGUI.index -= 1
    pygame.mixer.music.load(initiateJukebox.listOfSongs[constructGUI.index])
    pygame.mixer.music.play()
    constructGUI.updateLabel()

def stopSong(event):
    pygame.mixer.music.stop()
    constructGUI.labelVar.set("")



if __name__ == '__main__':
    main()

我应该如何编辑“ JukeboxGUI”类或“ constructGUI”变量来解决此问题？有什么想法吗？

Answer 1

constructGUI是在main中定义的，因此无法在该功能之外访问。

通过在全局范围内的函数外部放置占位符，使constructGUI成为全局变量。如果您需要在一个函数中进行修改（看起来像您的样子），请确保在该函数的顶部添加global constructGUI。

Answer 2

{<form action="edit_product.php" method="post" id="edit_product_form"> ... <input type="hidden" name="productID" value="<?php echo $product_id; ?>"> </form>仅在constructGUI范围内存在。您不会将其传递给其他功能，以使他们不知道它是什么。

使main()为模块级别的对象，以便每个人都能看到它。

constructGUI

文档中有一些内容需要阅读：Naming and Binding，A Word About Names and Objects and Python Scopes and Namespaces。

尝试在外部函数中更改类变量时出现NameError

2 个答案: