calculator.py help

[John Grayson]

In article <8uqrlv$f5b$1 at nnrp1.deja.com>,
  dijkhuis at my-deja.com wrote:
> Hello,
>
> Can someone please help me with the following code?
> I found this example somewhere but it won't work.
> It is supposed to be a calculator.
> Thanks,
>
> Dijkhuis
> ------
>
> from Tkinter import *
> from math import *
>
> def evaluate(event):
>     label['text']="result: " + str(eval(expression.get()))
>
> frame = Frame(None)
>
> entry = Entry(frame)
> entry['textvariable'] = expression = StringVar()
> entry.bind("",evaluate)
>
> label = Label(frame)
>
> button = Button(frame, text = "Submit", command = evaluate)
>
> frame.pack()
> entry.pack()
> label.pack()
> button.pack()
> frame.mainloop()
>


Rearranging your code - this works...

from Tkinter import *
from math import *

class Calculator:

    def __init__(self, master):
        self.frame = Frame(master)
        self.entry = Entry(self.frame)
        self.entry['textvariable'] = self.expression = StringVar()
        self.entry.bind("=",self.evaluate)

        self.label = Label(self.frame)
        self.button = Button(self.frame, text = "Submit",
                             command = self.evaluate)

        self.frame.pack()
        self.entry.pack()
        self.label.pack()
        self.button.pack()

    def evaluate(self, event=None):
         self.label['text']="result: " +
                             str(eval(self.expression.get()))

root = Tk()
calc = Calculator(root)
root.mainloop()

   John Grayson


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