Retrieval of widget property values

[Peter Otten]

Alex wrote:

> thanks Peter,
> 
> I'm probably not getting something, but how do show_size and
> show_button account for the changes in Entry? There are no references
> to the widget in either the function of the button. Sorry if the
> question is too dumb.

After

size_var = IntVar()
size_entry = Entry(..., textvariable=size_var)

Tkinter automatically synchronizes the value in the Entry with that in the 
IntVar. Therefore you can read the value shown in the Entry widget with

size_var.get()

Perhaps it becomes clearer in an interactive session:

>>> from Tkinter import *
>>> root = Tk()
>>> size_var = IntVar()
>>> size_entry = Entry(root, textvariable=size_var)
>>> size_entry.pack()
>>> size_var.set(42)

The Entry widget should show 42 now instead of the initial 0. Type 12345 
into the widget, then go back to the shell:

>>> size_var.get()
12345

Peter