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哪个tkinter属性表示tkinter是否仍在运行?

tkinter python

-1

lemi57ssss · 技术社区 · 6 年前

Tk是否有一个明确的属性,我可以检查它是否mainloop已经停止运行,或者根窗口是否已经被破坏?

下面的最小代码显示了一个由Tks传播python异常的明显失败引起的问题。要查看实际问题,请单击根窗口按钮,启动子窗口对话框。接下来,使用close window按钮(红色X)关闭根窗口。

import sys
import tkinter as tk

class ProgramIsEnding(Exception):
    pass


class UnrecognizedButtonException(Exception):
    pass


class MainWindow(tk.Tk):
    def __init__(self):
        super().__init__()
        self.title('Root Window')
        button = tk.Button(text='Start The Child Window Dialog')
        button.configure(command=self.run_dialog)
        button.grid()
        self.protocol('WM_DELETE_WINDOW', self.delete_window_callback)

    def delete_window_callback(self):
        self.destroy()
        print('Root has been destroyed')
        raise ProgramIsEnding

    def run_dialog(self):
        try:
            button = YesNoDialog(self)()
        except ProgramIsEnding:
            print('Doing end of program stuff.')
            return

        print(f"Button returned is '{button}'")
        if button == 'yes':
            print("'Yes' button clicked")
        elif button == 'no':
            print("'No' button clicked")
        else:
            msg = f"button '{button}'"
            raise UnrecognizedButtonException(msg)


class YesNoDialog:
    window: tk.Toplevel = None
    button_clicked = None

    def __init__(self, parent):
        self.parent = parent

    def __call__(self):
        self.create_window()
        return self.button_clicked

    def create_window(self):
        self.window = tk.Toplevel(self.parent)
        yes = tk.Button(self.window, text='Yes', command=self.yes_command)
        yes.pack(side='left')
        no = tk.Button(self.window, text='No', command=self.no_command)
        no.pack(side='left')
        self.window.wait_window()

    def yes_command(self):
        self.button_clicked = 'yes'
        self.window.destroy()

    def no_command(self):
        self.button_clicked = 'no'
        self.window.destroy()

def main():
    tkroot = MainWindow()
    tkroot.mainloop()


if __name__ == '__main__':
    sys.exit(main())

如果代码按预期工作,它将在捕获异常后正确终止,即ProgramIsEnding。相反,程序会以未处理的未识别ButtonException终止。下面是完整的错误消息。请注意,尽管try/except处理程序在从Tk将控制权交还给python之后无法使用programmisending异常,但还是通过stdout报告了该异常。

Root has been destroyed
Exception in Tkinter callback
Traceback (most recent call last):
  File "[â¦]/python3.7/tkinter/__init__.py", line 1702, in __call__
    return self.func(*args)
  File "[â¦]/wmdeletedemo.py", line 25, in delete_window_callback
     raise ProgramIsEnding
ProgramIsEnding
Exception in Tkinter callback
Traceback (most recent call last):
  File "[â¦]/python3.7/tkinter/__init__.py", line 1702, in __call__
    return self.func(*args)
  File "[â¦]/wmdeletedemo.py", line 41, in run_dialog
    raise UnrecognizedButtonException(msg)
UnrecognizedButtonException: button 'None'
Button returned is 'None'

一个明显的解决方法是检查按钮值是否为None,如果是,则返回。不过,对我来说,良好的实践建议我应该检查主要事件,既不依赖其次要效果,也不依赖于设置标志。

那么,Tk或tkinter是否还有其他属性记录mainloop的结束,或者根窗口是否已被破坏?

2 回复 | 直到 6 年前

Rachit Tayal 6 年前

可以在delete回调方法中将任何变量设置为true。然后您只需在正确的位置检查变量。像这样的。

def _delete_window_callback(self):
    """Carry out actions needed when main window is closed."""

    # Save the current geometry
    geometry = self.winfo_geometry()
    config.config_dynamic.set(self.config_section, self.config_geometry, geometry)

    destroyed = true

    # Destroy all widgets and end mainloop.
    self.destroy()

destroyed = false
if destroyed:
    break

lemi57ssss 6 年前

简而言之,Tk不设置属性。Tkinter通过提供 <Destroy> 每个小部件的事件。

装订机 <销毁> destroy_callback )将调用者和程序员与任何孩子的窗户。因此,程序员可以自由地集中精力处理闭包的效果。
A TkClosedWindow 出现异常时 YesNoDialog.__call__ 对于 MainWindow.run_dialog . 如果以后编写的任何代码都无法处理异常,程序将很快失败并显示错误消息。
YesNoDialog.window 因为Tk/Tcl不传播python异常。

import sys
import tkinter as tk


class TkClosedWindow(Exception):
    pass


class UnrecognizedButtonException(Exception):
    pass


class MainWindow(tk.Tk):
    def __init__(self):
        super().__init__()
        self.title('Root Window')
        button = tk.Button(text='Start The Child Window Dialog')
        button.configure(command=self.run_dialog)
        button.grid()

    def run_dialog(self):
        try:
            button = YesNoDialog(self)()
        except TkClosedWindow:
            print('Doing end of program stuff.')
            return

        print(f"Button returned is '{button}'")
        if button == 'yes':
            print("Yes button clicked")
        elif button == 'no':
            print("No button clicked")
        else:
            msg = f"button '{button}'"
            raise UnrecognizedButtonException(msg)


class YesNoDialog:
    window: tk.Toplevel = None
    button_clicked = None
    closed_by_tk = False

    def __init__(self, parent):
        self.parent = parent

    def __call__(self):
        self.create_window()
        if self.closed_by_tk:
            raise TkClosedWindow
        else:
            return self.button_clicked

    def create_window(self):
        self.window = tk.Toplevel(self.parent)
        self.window.bind('<Destroy>', self.destroy_callback)
        yes = tk.Button(self.window, text='Yes', command=self.yes_command)
        yes.pack(side='left')
        no = tk.Button(self.window, text='No', command=self.no_command)
        no.pack(side='left')
        self.window.wait_window()

    def yes_command(self):
        self.button_clicked = 'yes'
        self.window.destroy()

    def no_command(self):
        self.button_clicked = 'no'
        self.window.destroy()

    def destroy_callback(self, *args):
        self.closed_by_tk = True

def main():
    tkroot = MainWindow()
    tkroot.mainloop()


if __name__ == '__main__':
    sys.exit(main())