title: Combobox 'box_value'
body: <p>I'd like to put a combobox in my program and when I do something like this:</p>
  
  <pre><code>from Tkinter import Tk, StringVar
  from ttk import Label, Combobox,Frame,Button
  
  class App(Frame):
  
      def __init__(self,root):
          Frame.__init__(self, root)
          self.root = root
          self.combo()
          self.initUI()
  
      def combo(self):
          self.box_value=StringVar()
          self.box = Combobox(self, textvariable = self.box_value,state = 'readonly')
          self.box['values'] = ('a','b')
          self.box.current(0)
          self.box.grid(row=0,column =0)
      def initUI(self):
          self.lab = Label(self,text = '')
          self.lab.grid(row=1,column=0)
          self.but = Button(self,text ='OK',command = self.cho)
          self.but.grid(row=2,column=0)
      def cho(self):    
          x = self.box.get()
          self.lab.config(text = x)
  
  if __name__ == '__main__':
     root = Tk()
     App(root).pack()
     root.mainloop() 
  </code></pre>
  
  <p>It works properly. But when I put it into my another program It gives me an error that:     " Program instance has no attribute 'box_vaule' "
  Here is part of code:</p>
  
  <pre><code>class Program(Frame):
  
          def __init__(self, root):
  
              Frame.__init__(self, root)
              self.root = root       
              self.initUI()
              self.combo()
  
          def initUI(self):
  
              self.root.title('Emission')
              self.root.configure(background ='#6666ff')
              Style().configure('TFrame', background = '#6666ff')
              Style().configure('TButton',background = '#6666ff')
              grid all stuff....
  
          def combo(self):
              self.box_value = StringVar()
              self.box = Combobox(self,textvariable = self.box_vaule,state = 'readonly')
              self.box['values'] = ('a','b','c')
              self.box.current(0)
              self.box.grid(row=24,columnspan=6)
  if __name__=='__main__':
      root = Tk()
      Program(root).pack()
      root.mainloop()
  </code></pre>
  
  <p>I can not find any bugs in this code. Can anyone help me? Full error message is like this:
  "   self.box = Combobox(self,textvariable = self.box_vaule,state = 'readonly')
  AttributeError: Program instance has no attribute 'box_vaule'"</p>