小编use*_*997的帖子

我对面向对象编程相对较新,我无法弄清楚如何在python中删除实例化对象.任何帮助将非常感激.

        if self.hit_paddle(pos) == True or self.hit_paddle2(pos) == True:
            bar = bar + 1
        if bar == 1:
            global barbox1
            barbox1 = barfill(canvas)
            barbox1.canvas.move(barbox1.id, 253, 367)
        if bar == 2:
            global barbox2
            barbox2 = barfill(canvas)
            barbox2.canvas.move(barbox2.id, 293, 367)
        if bar == 3:
            global barbox3
            barbox3 = barfill(canvas)
            barbox3.canvas.move(barbox3.id, 333, 367)
        if bar == 4:
            global barbox4
            barbox4 = barfill(canvas)
            barbox4.canvas.move(barbox4.id, 373, 367)
        if bar == 5:
            global barbox5
            barbox5 = barfill(canvas)
            barbox5.canvas.move(barbox5.id, 413, 367)
            bar = 0
            time.sleep(0.2)
            barbox1 = …

嗨，我收到此代码的错误，即 StringVar() 未定义，这可能是一件小事，但我对 tkinter 没有经验，需要一些帮助，谢谢。

这是我的代码：

import tkinter as tk


class Converter1(tk.Tk):
    def __init__(self):
        tk.Tk.__init__(self)
        self.entry = tk.Entry(self)
        self.variable = StringVar()
        self.variable.set("Miles to Kilometers") # default dropdown menu value
        self.menu = tk.OptionMenu(self, variable, "Miles to Kilometers", "Kilometers to Miles")
        self.button = tk.Button(self, text="Convert!", command=self.convertMK)
        self.button.pack()
        self.menu.pack()
        self.button.pack()
        self.entry.pack()

    def convtertMK(self): # converts the miles and kilometers using the dropdown menu
        if var.get() == "Miles to Kilometers":
            print(int(self.entry.get()) * 1.6093)
        else:
            print(int(self.entry.get()) / 1.6093)        



converter = Converter1()

这是错误：

Traceback (most recent …