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我正在尝试创建 2OptionMenu相互依赖的方式，即第一个的选择将为第二个提供不同的选项。

我能够使用trace. 两个OptionMenus 都链接到一个命令，无论何时进行选择，都会在终端上打印一条消息。

虽然这适用于第一个OptionMenu，但在第二个进行选择时我无法打印任何内容。请注意，如果我两者OptionMenus没有动态链接到彼此（即，如果它们被构造为单独的小部件），那么打印对它们都非常有用。

关于可能是什么问题的任何想法？

这是说明问题的代码。

import tkinter as tk
from tkinter import *
from tkinter import ttk
from tkinter import messagebox

from PIL import ImageTk, Image

import os

#____________________________________________________________________________________________   
#This will be the main window
window = tk.Tk()
window.geometry('700x700')
window.title("daq")

#____________________________________________________________________________________________
#Lower frame
frame_main = Frame(window)
frame_main.place(rely=0.10, relx=0.0, relwidth=1.0)

#Create a tabcontrol
tabControl = ttk.Notebook(frame_main)
tabControl.grid(column=0, row=1)

# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#Digitizer tab
tab_Digitizer    = ttk.Frame(tabControl)
tabControl.add(tab_Digitizer, text='   Digitizer   ')
digitizer_tab_dummy_label = Label(tab_Digitizer, text="")
digitizer_tab_dummy_label.grid(column=0, row=0)

#~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#Channel settings

frame_channel_registers = Frame(tab_Digitizer)
frame_channel_registers.grid(column=0, row=4)

#Channel settings - general

frame_general_channel_registers = Frame(frame_channel_registers)
frame_general_channel_registers.grid(column=0, row=2, padx=25, sticky=W)

#Channel settings - PSD

frame_PSD_channel_registers = Frame(frame_channel_registers)
frame_PSD_channel_registers.grid(column=0, row=4, padx=25, sticky=W)

#Charge sensitivity
def charge_sensitivity_selection(event):
     print ("~!@#$%^&*()_+")
     #print ("Charge sensitivity       :", var_charge_sensitivity.get() )
     pass

lbl_charge_sensitivity = Label(frame_PSD_channel_registers, text="Charge sensitivity")
lbl_charge_sensitivity.grid(column=0, row=3, padx=25, sticky=W)


var_charge_sensitivity = StringVar(frame_PSD_channel_registers)
charge_sensitivity     = OptionMenu(frame_PSD_channel_registers, var_charge_sensitivity, '', command=charge_sensitivity_selection)
charge_sensitivity.grid(column=1, row=3, sticky=W)


#ADC range
def update_options(*args):
    adc_range=opt_ADC_range[var_ADC_range.get()]
    var_charge_sensitivity.set(adc_range[0])
    
    menu = charge_sensitivity['menu']
    menu.delete(0, 'end')
    
    for adc in adc_range:
         menu.add_command(label=adc, command=lambda sens=adc: var_charge_sensitivity.set(sens) )
         
def ADC_range_selection(event):
    print ("ADC range                 :", var_ADC_range.get() )
    pass
    
lbl_ADC_range = Label(frame_general_channel_registers, text="ADC range")
lbl_ADC_range.grid(column=0, row=1, padx=25, sticky=W)

opt_ADC_range = {'0.5':['1.25', '5', '20', '80', '320', '1280'], '2':['5', '20', '80', '320', '1280', '5120']}
var_ADC_range = StringVar(frame_general_channel_registers)
var_ADC_range.trace('w', update_options)
ADC_range     = OptionMenu(frame_general_channel_registers, var_ADC_range, *opt_ADC_range.keys(), command = ADC_range_selection)
var_ADC_range.set('2')
ADC_range.grid(column=1, row=1, sticky=W)

#This keeps the window open - has to be at the end
window.mainloop()
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1 回答 1

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如果您注释掉该行var_ADC_range.trace('w', update_options)，则会发生以下情况：

  • “充电灵敏度”菜单是“空的”，这意味着它有一个空条目
  • 如果您选择此条目，charge_sensitivity_selection则调用该函数
  • -> 你看到~!@#$%^&*()_+打印的

这意味着该update_options函数会覆盖选择“充电灵敏度”菜单中的条目时将调用的命令。这发生在以下行：

menu.add_command(label=adc, command=lambda sens=adc: var_charge_sensitivity.set(sens) )

可以尝试lambda用这样的函数对象替换上面一行中的表达式：

...
charge_sensitivity.grid(column=1, row=3, sticky=W)  # <- your code

class run_on_charge_sens_selection(object):         # <- the function object

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

    def __call__(self):
        # this function is called on menu selection
        var_charge_sensitivity.set(self.sens)
        charge_sensitivity_selection(self.sens)


#ADC range                                          # <- again your code
def update_options(*args):
    adc_range=opt_ADC_range[var_ADC_range.get()]
    var_charge_sensitivity.set(adc_range[0])
      
    menu = charge_sensitivity['menu']
    menu.delete(0, 'end')
      
    for adc in adc_range:                           # and now we use the function object
                                                    # instead of the lambda expression
         menu.add_command(label=adc, command=run_on_charge_sens_selection(adc))
...

我用函数对象传sens参数，调用函数的时候好像没有event。

我没有那么深入tkinter，也从未使用过trace，所以很可能有更简单的解决方案。

于 2021-04-20T20:34:01.410 回答