Tkinter ttk单选按钮变量更新失败

Question

What's wrong with this?

var = StringVar()
radBut1 = ttk.Radiobutton(root, text='A - Z', variable=var, value='AtoZ')
radBut2= ttk.Radiobutton(root, text='Z - A', variable=var, value='ZtoA')

When I select either of the 2 radiobuttons, the var variable is not updated. I found a lot of conflicting material in different documentation sources and tutorials (and I tried everything I found) to no avail.

I'm using the following to check the value of var:

print(var)

Answer 1

This works:

def updateRadioButtonVariable(radioButtonVar,updateString):
    radioButtonVar.set(updateString)

#Sort Type Radio Button
radioButtonVar = StringVar()
radBut1= ttk.Radiobutton(root, text='A - Z', variable=radioButtonVar, value='AtoZ',command= lambda: updateRadioButtonVariable(radioButtonVar ,'AtoZ'))
radBut2= ttk.Radiobutton(root, text='Z - A', variable=radioButtonVar, value='ZtoA',command= lambda: updateRadioButtonVariable(radioButtonVar ,'ZtoA'))

Not sure why the original code (which is almost template code from the documentation) doesn't work. If anyone has any ideas, please do share.