Python中的try-except块未处理异常

Question

我编写了一个简单的 python 代码，用于输入用户的任意数字。如果输入其他任何内容，则会根据代码引发异常。我将输入的值类型转换为 int 只是为了检查它是否是整数。理想情况下，除了当我输入任何字母表时，应该引发异常并打印我给出的文本。但我仍然可以看到它没有被抓住。

但是，当我专门在 typecast 语句周围再添加一个 try-except 块时，它就可以工作了。

from tkinter import *

window = Tk()
window.geometry('400x400')

class hangman:
    def __init__(self):
        self.entry = ''

    def clicked(self, label2):
        label2.place(x=100, y=200)

        while True:
            try:
                def get_value(event):
                    self.entry = e1.get()
                    self.entry = int(self.entry)
                    print(self.entry)

                Label(window, text="Enter any number :").place(x=10, y=220)

                e1 = Entry(window)
                e1.place(x=10, y=240)
                e1.bind('<Return>', get_value)  #To get the value entered in the entry when Return is pressed.
                print("Past bind1")
                print(self.entry)
                print("Past bind2")
                break

            except ValueError as e :
                print("\n\tPlease Enter only Numbers!!")


obj1    = hangman()
label2  = Label(window, text="Start")
bt      = Button(window, text="Play", command=lambda: obj1.clicked(label2))

bt.place(x=150, y=125)

window.mainloop()

我希望捕获异常并打印我的消息而不是标准异常错误。

Answer 1

如果你把 try/except 块放在get_value 函数中，异常会被正确捕获：

from tkinter import *
window = Tk()
window.geometry('400x400')


class hangman:
    def __init__(self):
        self.entry = ''

    def clicked(self, label2):
        label2.place(x=100, y=200)

        while True:
            def get_value(event):
                try:
                    self.entry = e1.get()
                    self.entry = int(self.entry)
                    print(self.entry)
                except ValueError as e:
                    print("\n\tPlease Enter only Numbers!!")

            Label(window, text="Enter any number :").place(x=10, y=220)

            e1 = Entry(window)
            e1.place(x=10, y=240)
            e1.bind('<Return>', get_value)  # To get the value entered in the entry when Return is pressed.
            print("Past bind1")
            print(self.entry)
            print("Past bind2")
            break


obj1 = hangman()
label2 = Label(window, text="Start")
bt = Button(window, text="Play", command=lambda: obj1.clicked(label2))

bt.place(x=150, y=125)

window.mainloop()