复选框验证：如何确保用户只能勾选一个复选框？

Question

I am trying to create a multiple choice quiz in Tkinter.

Each question has between 2-4 different answers all displayed as checkboxes, how do I ensure the user can only tick one check box and not all of them?

Thanks

Answer 1

Don't use checkboxes; use radoibuttons instead. The behavior of checkboxes and radiobuttons is well established -- checkboxes allow you to select N of N choices, radiobuttons are designed to allow you to select exactly 1 of N. Don't violate this design pattern or your users will be confused.

To make radiobuttons work, create a single StringVar and associate it with two or more radiobuttons. All of the radiobuttons that share the same variable will work as a set, allowing only one to be selected.

Answer 2

Although it's not stated by OP, if you're making a multiple choice quiz it might also be desirable for certain questions to have specific check boxes be mutually exclusive. Or, require that the user choose at most M out of N check boxes and have this requirement specifically stated in the question so that the user understands the design pattern. To do this you can take advantage of the callback option of Checkbuttons:

from Tkinter import *
master = Tk()

choices = [IntVar() for x in range(4)]
now = None
buttons = None
def cb():
  global now, buttons
  if None != now:
    buttons[now].deselect()
  vals = [choices[i].get() for i in range(4)]
  try: now = vals.index(1)
  except ValueError: now = None
  print "variables are",str([choices[i].get() for i in range(4)])

buttons = [Checkbutton(master, text="Choice "+str(i), variable=choices[i], command=cb) for i in range(4)]
for b in buttons: b.pack()

mainloop()

This example answers OPs specific question, but can be expanded upon to make legitimate changes to the operation of check boxes in specific situations.