Using Tkinter Drop-Down Menu choices as criteria for different commands

Question

I have been assigned with creating a simple Python project of my choice and as for now I am working on a little Tkinter GUI app. Having successfully written the part of the code responsible for multiple Drop-Down Menus, I wonder how to use combination of users' chosen options for creating commands opening the designated window. Is there any neat way to do it? Would it be enough to somehow define the combination of choices in the function, which constructs button command? Thank a lot for any piece of advice on this.

#first drop-down menu
 options1 = [
    '............',
    '............',
    '............'
]
chosen1 = StringVar()
chosen1.set('............')

vyber1 = OptionMenu(whiteboard, chosen1, *options1)
vyber1.place(relx = 0.35, rely = 0.35, relwidth = 0.35, relheight = 0.05)

# second drop-down menu
options2 = [
    '............',
    '............',
    '............',
    '............'
]
chosen2 = StringVar()
chosen2.set('............')

vyber2 = OptionMenu(whiteboard, chosen2, *options2)
vyber2.place(relx = 0.35, rely = 0.46, relwidth = 0.35, relheight = 0.05)

#third drop-down menu
options3 = [
    '............',
    '............',
    '............',
    '............'
]
chosen3 = StringVar()
chosen3.set('............')

vyber3 = OptionMenu(whiteboard, chosen3, *options3)
vyber3.place(relx = 0.35, rely = 0.57, relwidth = 0.35, relheight = 0.05)

Answer 1

A "neat" and orderly way to do it in Python would be to map each combination of choices to the desired window-opening function via a dictionary. Looking up the function to call would simply be a matter of combining the current choices together to form a dictionary key, then using that to look-up the corresponding function to call.

Below is a runnable example of doing that:

import tkinter as tk
from tkinter import messagebox

whiteboard = tk.Tk()
whiteboard.geometry('300x300')


#first drop-down menu
options1 = ['1', '2', '3']
chosen1 = tk.StringVar(value=options1[0])

vyber1 = tk.OptionMenu(whiteboard, chosen1, *options1)
vyber1.place(relx=0.35, rely=0.35, relwidth=0.35, relheight=0.10)

# second drop-down menu
options2 = ['A', 'B', 'C', 'D']
chosen2 = tk.StringVar(value=options2[0])

vyber2 = tk.OptionMenu(whiteboard, chosen2, *options2)
vyber2.place(relx=0.35, rely=0.46, relwidth=0.35, relheight=0.10)

#third drop-down menu
options3 = ['Red', 'Green', 'Blue', 'Yellow']
chosen3 = tk.StringVar(value=options3[0])

vyber3 = tk.OptionMenu(whiteboard, chosen3, *options3)
vyber3.place(relx=0.35, rely=0.57, relwidth=0.35, relheight=0.10)

# Window opening functions.
def open_window_1ARed():
    new_win = tk.Toplevel(whiteboard, width=80, height=20)
    new_win.title('1-A-Red window')
    tk.Label(new_win, text='Hello world').pack()

def open_window_1BBlue():
    new_win = tk.Toplevel(whiteboard, width=80, height=20)
    new_win.title('1-B-Blue window')
    tk.Label(new_win, text='Hello world').pack()

def display_error():
    messagebox.showerror('Sorry', "Unsupported combination!")

# Dictionary mapping combinations of choices to functions.
open_windows_commands = {
    '1ARed': open_window_1ARed,
    '1BBlue': open_window_1BBlue,
}

def open_window():
    key = f'{chosen1.get()}{chosen2.get()}{chosen3.get()}'
    open_window_command = open_windows_commands.get(key, display_error)
    open_window_command()

btn = tk.Button(whiteboard, text='Open window', command=open_window)
btn.place(relx=0.35, rely=0.80)

whiteboard.mainloop()