[Tutor] Tkinter GUI

Albert-Jan Roskam fomcl at yahoo.com
Tue Sep 11 21:10:43 CEST 2012

>    def calc_total(self):

>        """Update the text widget if they order Spaghetti Bolognese. """
>        try:
>            int(spag_ent.get())
>        except:
>            message="You have to enter a number in the quantity box. \n"
>The 'calc_total' function is supposed to calculate the users bill and then display it in the text widget, but every time I try it, it comes up as 0. Can anyone help me? 
It struck me that you're not assigning int(spag_ent.get()) to any variable:
spaghettiAmount = int(spag_ent.get())
Moreover, I'd try to create the program in such a way that it doesn't become a headache to change the menu (for instance, to add a new pasta).
Perhaps by using a dctionary as a parameter: menu = {"spaghetti": 4.50, "macaroni": 2.10, "calzone": 6.00}
Your example reminds me of one chapter of Head First Design Patterns (O'Reilly). Would be interesting to compare your approach with the one in the book.


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