Complete Tkinter Calculator

[uber1337]

I completed my calculator script, it now has features such as memory and +/-, it also has basic error handling. If you want to make one on your own, look at this and/or this. It handles string and int concatenation and zero division errors, and is 100% error proof(from my knowledge). Anyway, here is the source:

Code:

from Tkinter import *

mem = ''
class calc(Frame):
    def __init__(self):
        global result
        top = Tk()
        top.title('UberCalc v2.5')
        Frame.__init__(self)
        result = Entry()
        result.pack(side=TOP)
        buttons = ['M+', 'M', '+/-', '1', '2', '3','4', '5', '6','7', '8', '9','.', '0', 'Clear']
        operbtn = ['-','+', '*','/', '=']
        ro = 1
        col = 0
        for x in buttons:
            action = lambda y=x: onclick(y)
            Button(self, text=x, width=5, relief='ridge', command=action).grid(row=ro, column=col)
            col += 1
            if col > 2:
                col = 0
                ro += 1
        col = 4
        ro = 1
        for x in operbtn:
            action = lambda y=x:onclick(y)
            Button(self, text=x, width=5, relief='ridge', command=action).grid(row=ro, column=col)
            ro += 1

        def onclick(key):
            global result, mem
            if key == '=':
                try:
                    fetch = result.get()
                    answer = eval(fetch)
                    result.delete(0, END)
                    result.insert(0, answer)
                except(ZeroDivisionError):
                    result.delete(0,  END)
                    result.insert(0,  'Do not divide by zero please')
                except(SyntaxError):
                    result.delete(0,  END)
                    result.insert(0,  '0')
            elif key == 'Clear':
                result.delete(0, END)
            elif key == 'M+':
                mem = result.get()
                result.delete(0, END)
            elif key == 'M':
                result.insert(END, mem)
            elif key == '+/-':
                if result.get()[0] == '-':
                    result.delete(0)
                else:
                    result.insert(0, '-')
            else:
                result.insert(END, key)

if __name__ == '__main__':
    window = calc()
    window.pack()
    window.mainloop()

If you have any questions about how this works, feel free to ask on this thread. PM me or add me on MSN (ub3rl33t@msn.com) for any python questions.