_tkinter.TclError:无法删除Tcl命令- customtkinter -定制提示

Question

我需要什么

我试图在tkinter的帮助下实现一个自定义的“是/否”提示框。但是，我不想使用默认的messagebox，因为我需要以下两个功能：

• 默认值
• 小部件自毁并以默认值作为回答的倒计时。

什么是不可预测的错误？

我已经成功地用下面的代码实现了这些需求，但是当我在以下意义上使用这些小部件时，我会发现一些非常不可预测的行为：

• 有时一切都如预期的那样运作。当我按下按钮时，正确的答案会被存储，或者如果我让倒计时超时，默认答案就会被存储，或者如果我点击关闭窗口，它将正确地应用默认值作为答案。
• 但是，当我单击按钮时，我会得到一些_tkinter.TclError: invalid command name ".!ctkframe2.!ctkcanvas"错误(请参阅下面的执行日志中的整个堆栈跟踪)。

我怀疑这与计时器有关，因为当按下按钮时，错误并不总是会出现。真的快把我逼疯了..。

示例代码

# util_gui_classes.py
# -*- coding: utf-8 -*-

"""
Classes which serve for gui applications.
"""

from typing import Any

import tkinter
import tkinter.messagebox
import customtkinter


# ____________________________________________________________________________________________


customtkinter.set_appearance_mode('System')  # Modes: 'System' (standard), 'Dark', 'Light'
customtkinter.set_default_color_theme('blue')  # Themes: 'blue' (standard), 'green', 'dark-blue'


# ____________________________________________________________________________________________


class GuiPromptYesNo(customtkinter.CTk):
    """
    Creates a yes / no gui based prompt with default value and countdown functionality.
    The user input will be stored in:
    > instance.answer
    """
    WIDTH = 500
    HEIGHT = 200

    def __init__(self, question: str, default_value: str = 'no', countdown_seconds: int = 0):
        super().__init__()

        self.title('input required')
        self.geometry(f'{self.__class__.WIDTH}x{self.__class__.HEIGHT}')
        self.protocol('WM_DELETE_WINDOW', self.on_closing)  # call .on_closing() when app gets closed
        self.resizable(False, False)

        self.question = question
        self.answer = None
        self.default_value = default_value
        self.countdown_seconds = countdown_seconds
        self.remaining_seconds = countdown_seconds

        # ============ create top-level-frames ============

        # configure grid layout (4x1)
        self.equal_weighted_grid(self, 4, 1)
        self.grid_rowconfigure(0, minsize=10)
        self.grid_rowconfigure(3, minsize=10)

        self.frame_label = customtkinter.CTkFrame(master=self, corner_radius=10)
        self.frame_label.grid(row=1, column=0)

        self.frame_buttons = customtkinter.CTkFrame(master=self, corner_radius=0, fg_color=None)
        self.frame_buttons.grid(row=2, column=0)

        # ============ design frame_label ============

        # configure grid layout (5x4)
        self.equal_weighted_grid(self.frame_label, 5, 4)
        self.frame_label.grid_rowconfigure(0, minsize=10)
        self.frame_label.grid_rowconfigure(2, minsize=10)
        self.frame_label.grid_rowconfigure(5, minsize=10)

        self.label_question = customtkinter.CTkLabel(
            master=self.frame_label,
            text=self.question,
            text_font=('Consolas',),
        )
        self.label_question.grid(row=1, column=0, columnspan=4, pady=5, padx=10)

        self.label_default_value = customtkinter.CTkLabel(
            master=self.frame_label,
            text='default value: ',
            text_font=('Consolas',),
        )
        self.label_default_value.grid(row=3, column=0, pady=5, padx=10)

        self.entry_default_value = customtkinter.CTkEntry(
            master=self.frame_label,
            width=40,
            justify='center',
            placeholder_text=self.default_value,
            state='disabled',
            textvariable=tkinter.StringVar(value=self.default_value),
            text_font=('Consolas',),
        )
        self.entry_default_value.grid(row=3, column=1, pady=5, padx=10)

        if countdown_seconds > 0:
            self.label_timer = customtkinter.CTkLabel(
                master=self.frame_label,
                text='timer [s]: ',
                text_font=('Consolas',),
            )
            self.label_timer.grid(row=3, column=2, pady=5, padx=10)

            self.entry_timer = customtkinter.CTkEntry(
                master=self.frame_label,
                width=40,
                justify='center',
                state='disabled',
                textvariable=tkinter.StringVar(value=str(self.remaining_seconds)),
                placeholder_text=str(self.remaining_seconds),
                text_font=('Consolas',),
            )
            self.entry_timer.grid(row=3, column=3, pady=5, padx=10)

        # ============ design frame_buttons ============

        # configure grid layout (3x2)
        self.equal_weighted_grid(self.frame_buttons, 3, 2)
        self.frame_buttons.grid_rowconfigure(0, minsize=10)
        self.frame_buttons.grid_rowconfigure(2, minsize=10)

        self.button_yes = customtkinter.CTkButton(
            master=self.frame_buttons,
            text='yes',
            text_font=('Consolas',),
            command=lambda: self.button_event('yes'),
        )
        self.button_yes.grid(row=1, column=0, pady=5, padx=20)

        self.button_no = customtkinter.CTkButton(
            master=self.frame_buttons,
            text='no',
            text_font=('Consolas',),
            command=lambda: self.button_event('no'),
        )
        self.button_no.grid(row=1, column=1, pady=5, padx=20)

        if self.countdown_seconds > 0:
            self.countdown()

        self.attributes('-topmost', True)
        self.mainloop()

    # __________________________________________________________
    # methods

    @staticmethod
    def equal_weighted_grid(obj: Any, rows: int, cols: int):
        """configures the grid to be of equal cell sizes for rows and columns."""
        for row in range(rows):
            obj.grid_rowconfigure(row, weight=1)
        for col in range(cols):
            obj.grid_columnconfigure(col, weight=1)

    def button_event(self, answer):
        """Stores the user input as instance attribute `answer`."""
        self.answer = answer
        self.terminate()

    def countdown(self):
        """Sets the timer for the question."""
        if self.answer is not None:
            self.terminate()
        elif self.remaining_seconds < 0:
            self.answer = self.default_value
            self.terminate()
        else:
            self.entry_timer.configure(textvariable=tkinter.StringVar(value=str(self.remaining_seconds)))
            self.remaining_seconds -= 1
            self.after(1000, self.countdown)

    def stop_after_callbacks(self):
        """Stops all after callbacks on the root."""
        for after_id in self.tk.eval('after info').split():
            self.after_cancel(after_id)

    def on_closing(self, event=0):
        """If the user presses the window x button without providing input"""
        if self.answer is None and self.default_value is not None:
            self.answer = self.default_value
        self.terminate()

    def terminate(self):
        """Properly terminates the gui."""
        # stop all .after callbacks to avoid error message "Invalid command ..." after destruction
        self.stop_after_callbacks()

        self.destroy()


# ____________________________________________________________________________________________


if __name__ == '__main__':
    print('\n', 'do some python stuff before', '\n', sep='')

    q1 = GuiPromptYesNo(question='1. do you want to proceed?', countdown_seconds=5)
    print(f'>>>{q1.answer=}')

    print('\n', 'do some python stuff in between', '\n', sep='')

    q2 = GuiPromptYesNo(question='2. do you want to proceed?', countdown_seconds=5)
    print(f'>>>{q2.answer=}')

    print('\n', 'do some python stuff at the end', '\n', sep='')


# ____________________________________________________________________________________________

带有错误的执行日志

前三个测试成功的地方(包括点击按钮)，然后出现错误。

(py311) C:\Users\user\PycharmProjects\Sandbox\gui_tools>python util_guis.py

 do some python stuff before 

q1.answer='yes'

 do some python stuff in between 

q2.answer='no'

 do some python stuff at the end 


(py311) C:\Users\user\PycharmProjects\Sandbox\gui_tools>python util_guis.py

 do some python stuff before

q1.answer='yes'

 do some python stuff in between

q2.answer='yes'

 do some python stuff at the end


(py311) C:\Users\user\PycharmProjects\Sandbox\gui_tools>python util_guis.py

 do some python stuff before

q1.answer='no'

 do some python stuff in between

q2.answer='no'

 do some python stuff at the end


(py311) C:\Users\user\PycharmProjects\Sandbox\gui_tools>python util_guis.py

do some python stuff before

>>>q1.answer='yes'

do some python stuff in between

Exception in Tkinter callback
Traceback (most recent call last):
  File "C:\Program Files\Python311\Lib\tkinter\__init__.py", line 1948, in __call__
    return self.func(*args)
           ^^^^^^^^^^^^^^^^
  File "C:\Program Files\Python311\Lib\tkinter\__init__.py", line 861, in callit
    func(*args)
  File "C:\Users\user\PycharmProjects\Sandbox\gui_tools\util_guis.py", line 197, in countdown
    self.terminate()
  File "C:\Users\user\PycharmProjects\Sandbox\gui_tools\util_guis.py", line 224, in terminate
    child.destroy()
  File "C:\Users\user\python\shared_venvs\py311\Lib\site-packages\customtkinter\widgets\widget_base_class.py", line 85, in destroy
    super().destroy()
  File "C:\Program Files\Python311\Lib\tkinter\__init__.py", line 2635, in destroy
    for c in list(self.children.values()): c.destroy()
                                           ^^^^^^^^^^^
  File "C:\Users\user\python\shared_venvs\py311\Lib\site-packages\customtkinter\widgets\widget_base_class.py", line 85, in destroy
    super().destroy()
  File "C:\Program Files\Python311\Lib\tkinter\__init__.py", line 2639, in destroy
    Misc.destroy(self)
  File "C:\Program Files\Python311\Lib\tkinter\__init__.py", line 687, in destroy
    self.tk.deletecommand(name)
_tkinter.TclError: can't delete Tcl command
>>>q2.answer='no'

do some python stuff at the end


(py311) C:\Users\user\PycharmProjects\Sandbox\gui_tools>python util_guis.py

do some python stuff before

Exception in Tkinter callback
Traceback (most recent call last):
  File "C:\Program Files\Python311\Lib\tkinter\__init__.py", line 1948, in __call__
    return self.func(*args)
           ^^^^^^^^^^^^^^^^
  File "C:\Users\user\python\shared_venvs\py311\Lib\site-packages\customtkinter\widgets\ctk_button.py", line 377, in clicked
    self.command()
  File "C:\Users\user\PycharmProjects\Sandbox\gui_tools\util_guis.py", line 124, in <lambda>
    command=lambda: self.button_event('yes'),
                    ^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\user\PycharmProjects\Sandbox\gui_tools\util_guis.py", line 156, in button_event
    self.terminate()
  File "C:\Users\user\PycharmProjects\Sandbox\gui_tools\util_guis.py", line 186, in terminate
    self.destroy()
  File "C:\Users\user\python\shared_venvs\py311\Lib\site-packages\customtkinter\windows\ctk_tk.py", line 108, in destroy
    super().destroy()
  File "C:\Program Files\Python311\Lib\tkinter\__init__.py", line 2367, in destroy
    for c in list(self.children.values()): c.destroy()
                                           ^^^^^^^^^^^
  File "C:\Users\user\python\shared_venvs\py311\Lib\site-packages\customtkinter\widgets\widget_base_class.py", line 85, in destroy
    super().destroy()
  File "C:\Program Files\Python311\Lib\tkinter\__init__.py", line 2635, in destroy
    for c in list(self.children.values()): c.destroy()
                                           ^^^^^^^^^^^
  File "C:\Users\user\python\shared_venvs\py311\Lib\site-packages\customtkinter\widgets\widget_base_class.py", line 85, in destroy
    super().destroy()
  File "C:\Program Files\Python311\Lib\tkinter\__init__.py", line 2639, in destroy
    Misc.destroy(self)
  File "C:\Program Files\Python311\Lib\tkinter\__init__.py", line 687, in destroy
    self.tk.deletecommand(name)
_tkinter.TclError: can't delete Tcl command
Exception in Tkinter callback
Traceback (most recent call last):
  File "C:\Program Files\Python311\Lib\tkinter\__init__.py", line 1948, in __call__
    return self.func(*args)
           ^^^^^^^^^^^^^^^^
  File "C:\Users\user\python\shared_venvs\py311\Lib\site-packages\customtkinter\widgets\widget_base_class.py", line 142, in update_dimensions_event
    self.draw(no_color_updates=True)  # faster drawing without color changes
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\user\python\shared_venvs\py311\Lib\site-packages\customtkinter\widgets\ctk_frame.py", line 80, in draw
    requires_recoloring = self.draw_engine.draw_rounded_rect_with_border(self.apply_widget_scaling(self._current_width),
                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\user\python\shared_venvs\py311\Lib\site-packages\customtkinter\draw_engine.py", line 88, in draw_rounded_rect_with_border
    return self.__draw_rounded_rect_with_border_font_shapes(width, height, corner_radius, border_width, inner_corner_radius, ())
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "C:\Users\user\python\shared_venvs\py311\Lib\site-packages\customtkinter\draw_engine.py", line 207, in __draw_rounded_rect_with_border_font_shapes
    self._canvas.delete("border_parts")
  File "C:\Program Files\Python311\Lib\tkinter\__init__.py", line 2879, in delete
    self.tk.call((self._w, 'delete') + args)
_tkinter.TclError: invalid command name ".!ctkframe2.!ctkcanvas"
>>>q1.answer='yes'

do some python stuff in between

Exception in Tkinter callback
Traceback (most recent call last):
  File "C:\Program Files\Python311\Lib\tkinter\__init__.py", line 1948, in __call__
    return self.func(*args)
           ^^^^^^^^^^^^^^^^
  File "C:\Users\user\python\shared_venvs\py311\Lib\site-packages\customtkinter\widgets\ctk_button.py", line 377, in clicked
    self.command()
    super().destroy()
  File "C:\Program Files\Python311\Lib\tkinter\__init__.py", line 2639, in destroy
    Misc.destroy(self)
  File "C:\Program Files\Python311\Lib\tkinter\__init__.py", line 687, in destroy
    self.tk.deletecommand(name)
_tkinter.TclError: can't delete Tcl command
>>>q2.answer='no'

do some python stuff at the end


(py311) C:\Users\user\PycharmProjects\Sandbox\gui_tools>

要求

我使用Windows 11作为操作系统，并安装了一个带有定做机的虚拟python3.11环境。

编辑：

在@Thingamabobs回答的帮助下，我成功地实现了预期的行为而没有错误。以下是最终代码：

# util_gui_classes.py
# -*- coding: utf-8 -*-

"""
Classes which serve for gui applications.
"""

from typing import Any

import tkinter
import tkinter.messagebox
import customtkinter
from _tkinter import TclError


# _______________________________________________________________________


customtkinter.set_appearance_mode('System')  # Modes: 'System' (standard), 'Dark', 'Light'
customtkinter.set_default_color_theme('blue')  # Themes: 'blue' (standard), 'green', 'dark-blue'


# _______________________________________________________________________


class GuiPromptYesNo(customtkinter.CTk):
    """
    Creates a yes / no gui based prompt with default value and countdown functionality.
    The user input will be stored in:
    >>> instance.answer
    """
    WIDTH = 500
    HEIGHT = 200

    def __init__(self, question: str, default_value: str = 'no', countdown_seconds: int = 0):
        super().__init__()
        self.terminated = False

        self.title('input required')
        self.geometry(f'{self.__class__.WIDTH}x{self.__class__.HEIGHT}')
        self.protocol('WM_DELETE_WINDOW', self.on_closing)  # call .on_closing() when app gets closed
        self.resizable(False, False)

        self.question = question
        self.answer = None
        self.default_value = default_value
        self.countdown_seconds = countdown_seconds
        self.remaining_seconds = countdown_seconds

        # ============ create top-level-frames ============

        # configure grid layout (4x1)
        self.equal_weighted_grid(self, 4, 1)
        self.grid_rowconfigure(0, minsize=10)
        self.grid_rowconfigure(3, minsize=10)

        self.frame_label = customtkinter.CTkFrame(master=self, corner_radius=10)
        self.frame_label.grid(row=1, column=0)

        self.frame_buttons = customtkinter.CTkFrame(master=self, corner_radius=0, fg_color=None)
        self.frame_buttons.grid(row=2, column=0)

        # ============ design frame_label ============

        # configure grid layout (5x4)
        self.equal_weighted_grid(self.frame_label, 5, 4)
        self.frame_label.grid_rowconfigure(0, minsize=10)
        self.frame_label.grid_rowconfigure(2, minsize=10)
        self.frame_label.grid_rowconfigure(5, minsize=10)

        self.label_question = customtkinter.CTkLabel(
            master=self.frame_label,
            text=self.question,
            text_font=('Consolas',),
        )
        self.label_question.grid(row=1, column=0, columnspan=4, pady=5, padx=10)

        self.label_default_value = customtkinter.CTkLabel(
            master=self.frame_label,
            text='default value: ',
            text_font=('Consolas',),
        )
        self.label_default_value.grid(row=3, column=0, pady=5, padx=10)

        self.entry_default_value = customtkinter.CTkEntry(
            master=self.frame_label,
            width=40,
            justify='center',
            placeholder_text=self.default_value,
            state='disabled',
            textvariable=tkinter.StringVar(value=self.default_value),
            text_font=('Consolas',),
        )
        self.entry_default_value.grid(row=3, column=1, pady=5, padx=10)

        if countdown_seconds > 0:
            self.label_timer = customtkinter.CTkLabel(
                master=self.frame_label,
                text='timer [s]: ',
                text_font=('Consolas',),
            )
            self.label_timer.grid(row=3, column=2, pady=5, padx=10)

            self.entry_timer = customtkinter.CTkEntry(
                master=self.frame_label,
                width=40,
                justify='center',
                state='disabled',
                textvariable=tkinter.StringVar(value=str(self.remaining_seconds)),
                placeholder_text=str(self.remaining_seconds),
                text_font=('Consolas',),
            )
            self.entry_timer.grid(row=3, column=3, pady=5, padx=10)

        # ============ design frame_buttons ============

        # configure grid layout (3x2)
        self.equal_weighted_grid(self.frame_buttons, 3, 2)
        self.frame_buttons.grid_rowconfigure(0, minsize=10)
        self.frame_buttons.grid_rowconfigure(2, minsize=10)

        self.button_yes = customtkinter.CTkButton(
            master=self.frame_buttons,
            text='yes',
            text_font=('Consolas',),
            command=lambda: self.button_event('yes'),
        )
        self.button_yes.grid(row=1, column=0, pady=5, padx=20)

        self.button_no = customtkinter.CTkButton(
            master=self.frame_buttons,
            text='no',
            text_font=('Consolas',),
            command=lambda: self.button_event('no'),
        )
        self.button_no.grid(row=1, column=1, pady=5, padx=20)

        if self.countdown_seconds > 0:
            self.countdown()

        self.attributes('-topmost', True)
        self.mainloop()

    # __________________________________________________________
    # methods

    @staticmethod
    def equal_weighted_grid(obj: Any, rows: int, cols: int):
        """configures the grid to be of equal cell sizes for rows and columns."""
        for row in range(rows):
            obj.grid_rowconfigure(row, weight=1)
        for col in range(cols):
            obj.grid_columnconfigure(col, weight=1)

    def button_event(self, answer):
        """Stores the user input as instance attribute `answer`."""
        self.answer = answer
        self.terminate()

    def countdown(self):
        """Sets the timer for the question."""
        if self.answer is not None:
            self.terminate()
        elif self.remaining_seconds < 0:
            self.answer = self.default_value
            self.terminate()
        else:
            self.entry_timer.configure(textvariable=tkinter.StringVar(value=str(self.remaining_seconds)))
            self.remaining_seconds -= 1
            self.after(1000, self.countdown)

    def stop_after_callbacks(self):
        """Stops all after callbacks on the root."""
        for after_id in self.tk.eval('after info').split():
            self.after_cancel(after_id)

    def on_closing(self, event=0):
        """If the user presses the window x button without providing input"""
        if self.answer is None and self.default_value is not None:
            self.answer = self.default_value
        self.terminate()

    def terminate(self):
        """Properly terminates the gui."""
        # stop all .after callbacks to avoid error message "Invalid command ..." after destruction
        self.stop_after_callbacks()

        if not self.terminated:
            self.terminated = True
            try:
                self.destroy()
            except TclError:
                self.destroy()


# _______________________________________________________________________


if __name__ == '__main__':
    print('before')

    q1 = GuiPromptYesNo(question='1. do you want to proceed?', countdown_seconds=5)
    print(f'>>>{q1.answer=}')

    print('between')

    q2 = GuiPromptYesNo(question='2. do you want to proceed?', countdown_seconds=5)
    print(f'>>>{q2.answer=}')

    print('after')


# _______________________________________________________________________

顺便说一句:这个类也可以在我的包utils_nm中找到，它位于模块util_gui_classes中。

Answer 1

而我没有Ctk给你确切的密码。我可以告诉你到底出了什么问题，你需要怎么解决。

在这里之后，您有自我重复的功能：

def countdown(self):
        """Sets the timer for the question."""
        if self.answer is not None:
            self.terminate()
        elif self.remaining_seconds < 0:
            self.answer = self.default_value
            self.terminate()
        else:
            self.entry_timer.configure(textvariable=tkinter.StringVar(value=str(self.remaining_seconds)))
            self.remaining_seconds -= 1
            self.after(1000, self.countdown)

您所面临的问题是，您试图delete已在一个事后调用中已被破坏的窗口。因此，取决于哪个事件运行得更快，您是否遇到了错误。

为什么会发生这种事？

当您给出一个指令时，不管它是什么(除了一些例外，例如更新)，它都被放置在一个事件队列中，并以某种形式的FIFO (先进先出)调度。所以最古老的事件就会被处理。这意味着您可以尝试取消警报，但在实际取消警报之前运行警报。

如何解决？

有不同的方法可供选择。在我看来，最简单和最干净的解决方案是设置一个标志，避免试图破坏一个已经被破坏的窗口。类似于：

    def __init__(self, question: str, default_value: str = 'no', countdown_seconds: int = 0):
        super().__init__()
        self.terminated = False

并将其设置为：

def terminate(self):
    """Properly terminates the gui."""
    # stop all .after callbacks to avoid error message "Invalid command ..." after destruction
    #self.stop_after_callbacks() shouldn't be needed
    if not self.terminated:
        self.terminated = True
        self.destroy()

除了上述建议的之外，我建议您为WM_DELETE_WINDOW设置一个协议处理程序并设置标志，因为它可能也是通过窗口管理器销毁窗口来实现的。

不同的方法是在terminate中捕获except _tkinter.TclError:的try和except块。但请注意下划线，该模块不打算使用，它可能会在未来改变，并可能再次破坏您的应用程序，即使这似乎不太可能。