[Tutor] help with Tkinter, please

[Dick Moores]

At 08:01 AM 11/23/2006, Michael Lange wrote:
>On Thu, 23 Nov 2006 02:07:17 -0800
>Dick Moores <rdm at rcblue.com> wrote:
>
> > I think I see how to make a simple GUI with Tkinter, but I still
> > don't see how to use one with even a simple, previously non-GUI
> > Python script. I'm wondering if someone could create an example for
> > me, using the 2 functions fact() and printFact() at
> > <http://www.rcblue.com/Python/fact.txt>. I'm thinking of something
> > really plain and simple. A frame widget, an entry widget, and a text
> > widget. The user enters an integer n (which can be very large), and
> > the text widget shows n! in 2 formats, as the output of a modified
> > printFact(). Maybe a button is also necessary?
> >
>
>Hi Dick,
>
>assuming the functions you want to use are in a separate module "fact.py",
>a simple (and dirty) solution might look like
>
>from Tkinter import *
>import fact
>
>root = Tk()
>entry = Entry(root)
>entry.pack(side='top')
>text = Text(root)
>text.pack(side='top')
>
># now you need a callback that calls fact() and inserts the result 
>into the text widget
>def compute_fact():
>     value = int(entry_get())
>     result = fact.fact(value)
>     newtext = 'Result: %d\n' % result# change this to the output 
> format you wish
>     text.insert('end', result)
>
>button = Button(root, text="Compute fact", command=compute_fact)
>button.pack(side='top')
>root.mainloop()
>
>In case you do not want an extra button, you can bind the 
>compute_fact() callback
>to Key-Return events for the entry:
>
>entry.bind('<Return>', compute_fact)
>
>however you will have to change the callback's constructor to accept 
>an event object
>as argument:
>
>def compute_fact(event):
>     (...)
>
>or :
>
>def compute_fact(event=None):
>     (...)
>
>which allows both.
>
>In case you want the output formatting done in the fact module, 
>change the printFact() function,
>so that it *returns* a string instead of printing it to stdout, so 
>you can use a callback like:
>
>def compute_fact(event=None):
>     text.insert('end', fact.printFact(int(entry.get())))

Thanks very much, Michael.

OK, here's my attempt, using my fact(), but not printFact():

============================================
from Tkinter import *

def fact(n):
         """
         compute n!
         This is faster than the often-seen factorial function using recursion
         """
         product = 1
         while n > 1:
                 product *= n
                 n -= 1
         return product

root = Tk()
entry = Entry(root)
entry.pack(side='top')
text = Text(root)
text.pack(side='top')

# now you need a callback that calls fact() and inserts the result 
into the text widget
def compute_fact():
         value = int(entry_get())
         result = fact(value)
         newtext = 'Result: %d\n' % result# change this to the output 
format you wish
         text.insert('end', result)


button = Button(root, text="Compute fact", command=compute_fact)
button.pack(side='top')
root.mainloop()
=====================================================

I entered an integer, pressed the button "Compute fact", and got the error,

E:\Python25\dev\Tkinter>python factTk1-a.py
Exception in Tkinter callback
Traceback (most recent call last):
   File "E:\Python25\lib\lib-tk\Tkinter.py", line 1403, in __call__
     return self.func(*args)
   File "factTk1-a.py", line 22, in compute_fact
     value = int(entry_get())
NameError: global name 'entry_get' is not defined

I'm so dumb I don't see how to define it.

Dick