AttributeError in tkinter

Question

I am trying to write a program with tkinter. I have not finished the program but trying to run it just to see how my window will look, I get an error inside of tkinter.

I am not sure what to do now. Anybody know what it wrong?

Here is the message

Traceback (most recent call last):
  File "<string>", line 420, in run_nodebug
  File "<module1>", line 53, in <module>
  File "<module1>", line 50, in main
  File "<module1>", line 23, in __init__
  File "C:\Python33\lib\tkinter\__init__.py", line 2110, in __init__
    Widget.__init__(self, master, 'button', cnf, kw)
  File "C:\Python33\lib\tkinter\__init__.py", line 2036, in __init__
    classes = [(k, v) for k, v in cnf.items() if isinstance(k, type)]
AttributeError: 'str' object has no attribute 'items'

import tkinter
import tkinter.messagebox

#---------------------- define GUI class
class CalcMPG:
    def __init__(self):
        self.main_window = tkinter.Tk()

        #-------------- create 3 frames ---------
        self.uframe= tkinter.Frame(self.main_window) #upper frame
        self.mframe= tkinter.Frame(self.main_window) #middle frame
        self.bframe= tkinter.Frame(self.main_window) #button frame

        #------------ create the 3 label widgets ------------
        self.lblgal= tkinter.Label(self.uframe, text="Enter # of gallons used")
        self.lblmiles= tkinter.Label(self.mframe, text="Enter miles travelled")

        #------------ create the 2 Entry widgets ------------
        self.entgal= tkinter.Entry(self.uframe, width=10)
        self.entmiles= tkinter.Entry(self.mframe, width=10)

        #------------ create the 2 Button widgets -----------
        self.mpgbtn = tkinter.Button(self.bframe, "Calcualte MPG")
        self.extbtn = tkinter.Button(self.bframe, "Exit")


        #-------- pack upper frame -----------
        self.lblgal.pack(side='left')
        self.entgal.pack(side='right')

        #------- pack middle frame ----------
        self.lblmiles.pack(side='left')
        self.entmiles.pack(side='right')

        #------- pack bottom frome ----------
        self.mpgbtn.pack(side= 'left')
        self.extbtn.pack(side= 'right')


        #------- pack frames --------
        self.uframe.pack(side='top')
        self.mframe.pack(side='top')
        self.bframe.pack(side='top')


        tkinter.mainloop()

#--------------- define main function  ----
def main():
    calcmpg = CalcMPG()

#--------- invoke main function -------
main()

Answer 1

You need to create the buttons like this, i.e. specify explicitely that those string values are the values of the text property of the button, just as you did with the labels:

self.mpgbtn = tkinter.Button(self.bframe, text="Calculate MPG")
self.extbtn = tkinter.Button(self.bframe, text="Exit")