Tkinter：动态链接选项菜单时不打印函数

Question

我正在尝试创建 2 个相互依赖的OptionMenu，以便第一个选择将为第二个提供不同的选项。

我能够使用trace将这两者链接在一起。 两个OptionMenu都链接到一个命令，每当进行选择时，都会在终端上打印一条消息。

虽然这适用于第一个OptionMenu，但在第二个选择时我无法打印任何内容。请注意，如果我的两个OptionMenus没有动态地相互链接(即，如果它们被构造为单独的小部件)，则打印对它们都非常有用。

对可能是什么问题的任何想法？

下面是说明该问题的代码。

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()

Answer 1

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

">

• 电荷灵敏度"菜单是"空的"，这意味着它有一个空条目
• 如果选择此项，则调用charge_sensitivity_selection函数
• ->你看到打印~!@#$%^&*()_+

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

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

可以尝试将上面行中的lambda表达式替换为如下所示的函数对象：

...
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))
...

我使用函数对象传递sens参数，调用函数时似乎没有event。

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