Python AttributeError 实例没有属性

Question

我收到以下错误：-

AttributeError: PageOne instance has no attribute 'scann'

我正在尝试运行一个 bash 脚本（运行重点）。仍然无法弄清楚为什么我会收到此错误。我的代码如下：-

class PageOne(tk.Frame):

    def __init__(self, parent, controller):

        running = False  # Global flag

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

        button = tk.Button(self, text="Go to the start page",
                           command=lambda: controller.show_frame("StartPage"))
        strt = tk.Button(self, text="Start Scan", command=self.start)
        stp = tk.Button(self, text="Stop", command=self.stop)

        button.pack()       
        strt.pack()
        stp.pack()
        self.after(1000, self.scann)  # After 1 second, call scanning

    def scann(self):
        if running:
          sub.call(['./runfocus'], shell=True)

        self.after(1000, self.scann)

    def start(self):
        """Enable scanning by setting the global flag to True."""
        global running
        running = True

    def stop(self):
        """Stop scanning by setting the global flag to False."""
        global running
        running = False

请提出您宝贵的建议。

Answer 1

我无法重现 AttributeError: PageOne instance has no attribute 'scann' error，但由于 running 标志，您的脚本还有其他问题。您应该避免使用可修改的全局变量，并且当您已经有了 class 时，绝对没有必要使用单独的全局变量。只需创建一个属性作为标志。

这是您的代码的可运行修复版本。我用一个简单的 print 调用替换了 sub.call(['./runfocus'], shell=True) 调用，这样我们就可以看到 start 和 stop 行为正确。

import tkinter as tk

class PageOne(tk.Frame):
    def __init__(self, parent, controller):
        self.running = False

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

        button = tk.Button(self, text="Go to the start page",
                           command=lambda: controller.show_frame("StartPage"))
        strt = tk.Button(self, text="Start Scan", command=self.start)
        stp = tk.Button(self, text="Stop", command=self.stop)

        button.pack()
        strt.pack()
        stp.pack()
        self.after(1000, self.scann)  # After 1 second, call scanning

    def scann(self):
        if self.running:
            #sub.call(['./runfocus'], shell=True)
            print("calling runfocus")

        self.after(1000, self.scann)

    def start(self):
        """Enable scanning by setting the flag to True."""
        self.running = True

    def stop(self):
        """Stop scanning by setting the flag to False."""
        self.running = False


root = tk.Tk()
frame = PageOne(root, root)
frame.pack()
root.mainloop()

Python AttributeError 实例没有属性

Python AttributeError instance has no attribute

python

tkinter

attributeerror