如何使用回调来更改多个 tkinter 检查按钮

Question

我有多个 tk.Checkbuttons 在单击（或更改）时应该共享相同的回调。复选框的变量（状态）应该在状态更改时触发的回调中可用（并用于所有检查按钮）。有很多这样的文章，其中大多数处理状态变量的并行列表。因为我想避免单独的变量列表，因为 checkboxex 的数量会因数据变化而变化，所以我在两个版本中创建了自己的 Checkbutton 类，但两个版本都有缺点，所以我需要一些建议。

这两个类都包含一个状态变量的实例来保存状态（避免管理状态的单独变量列表）并在单击时触发操作。所以我的问题与回调有关。

第一个类显示在这个最小化的运行示例中：

#!/usr/bin/env python3
from tkinter import *
import tkinter as tk
#-------------------------------------------------------------------------------
# myCheckButton: CheckButton containing state, that can be identified
#                in action(command) procedure
# Parameters:
# userdata: User defined, for example index of a database table row related to the CB
# action  : command to execute when clicked. Replaces command variable because
#           command does not provide the event information when called. Event
#           information is needed to get the checkbox data within action.
class myCheckButton(tk.Checkbutton):
  def __init__(self, parent, userdata, action, *args, **kwargs):
    # state holds the state of the CB (False = unchecked, True = checked)
    self.state = BooleanVar(value=False)
    # add the state variable to tk.Ckeckbutton args
    kwargs['variable'] = self.state
    # init tk.Checkbutton
    super().__init__(parent, *args, **kwargs)
    # bind action to myCheckButton using <Button-1> (left mouse button)
    self.bind('<Button-1>', action)
    # store userdata for usage in the action procedure
    self.userdata = userdata
#-------------------------------------------------------------------------------
def onCbClicked(event):
  # get the calling widget containing all data we need to know
  sender = event.widget
  # get the status of CB. "not" because action runs before status change
  status = not sender.state.get()
  # do something by using text, status and/or user defined variable
  if status == True:
    print("CB("  + sender["text"] + "): Data " + str(sender.userdata) + " is checked")
  else:
    print("CB("  + sender["text"] + "): Data " + str(sender.userdata) + " is unchecked")
#-------------------------------------------------------------------------------
# Main window defs
root = tk.Tk()
root.title("myCheckButton")
root.geometry('300x60')
# 1st instance of myCheckButton
mycb1 = myCheckButton(root, text="Test A", userdata=1, action=onCbClicked)
mycb1.grid(row=0, column=0)
# 2nd instance of myCheckButton
mycb2 = myCheckButton(root, text="Test B", userdata=2, action=onCbClicked)
mycb2.grid(row=1, column=0)
# just for example: Set state of mycb2 to true
mycb2.state.set(True)
root.mainloop()

这里的缺点是回调仅在单击时调用，而不是在我调用 .state.set(bool) 更改状态时调用（参见倒数第二行）。有没有办法（除了我使用跟踪的第二个解决方案）来解决这个问题？优点是我可以使用传递给它的事件在回调中清楚地识别调用实例。

第二种解决方案类似，其优点是当状态变量发生变化时也会调用回调，而无需单击小部件。缺点是我必须通过将跟踪变量命名为与实例相同的名称来传递 Checkbutton 的实例名称以在回调中识别它。另外，我不确定这种识别调用实例的方式是否保存。

我的第二个解决方案的最小化示例：

#!/usr/bin/env python3
from tkinter import *
import tkinter as tk
#-------------------------------------------------------------------------------
# myCheckButton: CheckButton containing state, that can be identified
#                in action(command) procedure
# Parameters:
# instName: Name of the CB instance to use in onCbChange
# userdata: User defined, for example index of a database table row related to the CB
# action  : command to execute when status changes.
class myCheckButton(tk.Checkbutton):
  def __init__(self, parent, instName, userdata, action, *args, **kwargs):
    # state holds the state of the CB (False = unchecked, True = checked)
    # the name of the internal variable is set to the instance name of this class.
    self.state = BooleanVar(value=False, name=instName)
    # Trace the state variable to call action procedure when it changes.
    self.state.trace("w", action)
    # add the state variable to tk.Ckeckbutton args
    kwargs['variable'] = self.state
    # init tk.Checkbutton
    super().__init__(parent, *args, **kwargs)
    # store userdata for usage in the action procedure
    self.userdata = userdata
#-------------------------------------------------------------------------------
def onCbChange(*args):
  # get the calling widget containing all data we need to know from *args.
  # This requires the name of the traced variable is the same as name of the widget instance.
  sender = eval(args[0])
  # get the status of CB.
  status = sender.state.get()
  # do something by using text, status and/or user defined variable
  if status == True:
    print("CB("  + sender["text"] + "): Data " + str(sender.userdata) + " is checked")
  else:
    print("CB("  + sender["text"] + "): Data " + str(sender.userdata) + " is unchecked")
#-------------------------------------------------------------------------------
# Main window defs
root = tk.Tk()
root.title("myCheckButton")
root.geometry('300x60')
# 1st instance of myCheckButton
mycb1 = myCheckButton(root, text="Test A", instName="mycb1", userdata=1, action=onCbChange)
mycb1.grid(row=0, column=0)
# 2nd instance of myCheckButton
mycb2 = myCheckButton(root, text="Test B", instName="mycb2", userdata=2, action=onCbChange)
mycb2.grid(row=1, column=0)
# just for example: Set state of mycb2 to true
mycb2.state.set(True)
root.mainloop()

即使这是我的首选解决方案： 通过传递给跟踪回调的第一个参数的 eval 确定调用实例是否保存（假设正确的名称被传递给构造函数）？有没有更好的方法来识别呼叫者？例如通过以某种方式传递事件以能够识别调用者，类似于第一个解决方案？

提前感谢您的帮助。

编辑：

按照 acw1668 的提示，我将 myCheckButton 类从第一个解决方案更改为：

class myCheckButton(tk.Checkbutton):
  def __init__(self, parent, userdata, action, *args, **kwargs):
    # state holds the state of the CB (False = unchecked, True = checked)
    self.state = BooleanVar(value=False)
    # add the state variable to tk.Ckeckbutton args
    kwargs['variable'] = self.state
    # init tk.Checkbutton
    super().__init__(parent, *args, **kwargs)
    # bind action to myCheckButton using <Button-1> (left mouse button)
    self.bind('<Button-1>', action)
    # store userdata for usage in the action procedure
    self.userdata = userdata
    # store action
    self.action = action
    # add widget property
    self.widget = self
  def set(self, status):
    # only when status changes:
    if status != self.state.get():
      # callback before status change
      self.action(self)
      # change status
      self.state.set(status)

我不确定从 set 过程将“事件”传递给回调的方法是否最好，但它在调用 .set(bool) 时有效。

最终解决方案

这是自定义检查按钮的完整最终解决方案。感谢 Matiiss 和 acw1668：

#!/usr/bin/env python3
from tkinter import *
import tkinter as tk
#-------------------------------------------------------------------------------
# myCheckButton: CheckButton containing state, that can be identified
#                in action(command) procedure
# Parameters:
# userdata: User defined, for example index of a database table row related to the CB
class myCheckButton(tk.Checkbutton):
  def __init__(self, parent, userdata, *args, **kwargs):
    # state holds the state of the CB (False = unchecked, True = checked)
    self.state = BooleanVar(value=False)
    # add the state variable to tk.Ckeckbutton args
    kwargs['variable'] = self.state
    # init tk.Checkbutton
    super().__init__(parent, *args, **kwargs)
    # store userdata for usage in the action procedure
    self.userdata = userdata
  def set(self, status):
    # only when status changes:
    if status != self.state.get():
      if status == True: self.deselect()
      else:              self.select()
      self.invoke()
#-------------------------------------------------------------------------------
def onCbClicked(sender):
  # get the status of CB.
  status = sender.state.get()
  # do something by using text, status and/or user defined variable
  if status == True:
    print("CB("  + sender["text"] + "): Data " + str(sender.userdata) + " is checked")
  else:
    print("CB("  + sender["text"] + "): Data " + str(sender.userdata) + " is unchecked")
#-------------------------------------------------------------------------------
# Main window defs
root = tk.Tk()
root.title("myCheckButton")
root.geometry('300x60')
# 1st instance of myCheckButton
mycb1 = myCheckButton(root, text="Test A", userdata=1, command=lambda: onCbClicked(mycb1))
mycb1.grid(row=0, column=0)
# 2nd instance of myCheckButton
mycb2 = myCheckButton(root, text="Test B", userdata=2, command=lambda: onCbClicked(mycb2))
mycb2.grid(row=1, column=0)
# just for example: Set state of mycb2 to test status change callback
mycb2.set(True)
root.mainloop()

Answer 1

我还是有点困惑，但这就是你想要的：

from tkinter import Tk, Checkbutton


root = Tk()

c = Checkbutton(root, text='Apple')
c.pack()
c.bind('<Button-1>', lambda e: print(e.widget))

root.mainloop()

使用这样的函数来模拟用户与复选框的交互（选中用于选择，取消选中用于取消选择）

def check():
    c.deselect()
    c.invoke()
    

def uncheck():
    c.select()
    c.invoke()

你只需要找到一种方法来调用这些函数

完整的代码示例：

from tkinter import Tk, Checkbutton, Button, IntVar


def toggle(widget):
    state = var.get()
    if state == 0:
        print('off')
    if state == 1:
        print('on')
    print(widget)


def check():
    c.deselect()
    c.invoke()


def uncheck():
    c.select()
    c.invoke()


root = Tk()

var = IntVar()

c = Checkbutton(root, text='Apple', variable=var, command=lambda: toggle(c))
c.pack()

Button(root, text='On', command=check).pack()
Button(root, text='Off', command=uncheck).pack()

root.mainloop()

请注意，使用按钮会触发复选框命令，而仅使用 .select/.deselect 不会这样做