require 'tk'

n = TkVariable.new(0)

TkFrame.new{|f|
  TkRadiobutton.new(f, 'text'=>'one', 'value'=>1, 'variable'=>n).pack('anchor'=>'w')
  TkRadiobutton.new(f, 'text'=>'two', 'value'=>2, 'variable'=>n).pack('anchor'=>'w')
  TkRadiobutton.new(f, 'text'=>'three', 'value'=>3, 'variable'=>n).pack('anchor'=>'w')
}.pack

TkLabel.new(nil, 'textvariable'=>n, 'relief'=>'groove', 'padx'=>'4').pack

Tk.mainloop