Straight from the Ministry of Silly Walks

[Brian & Colleen]

The following code is part of gui8.py from "Programming Python":

    def quit(self):
        ans = Dialog(self, title   = 'Verify quit',
                           text    = 'Are you sure you want to quit?',
                           bitmap  = 'question',
                           default = 1,
                           strings = ('Yes', 'No'))
        if ans.num == 0:
                  Frame.quit(self)

It works (no surprise there -- the author knows his stuff).

I paste the same piece of code into a very similar program and get a
stack trace of:

Exception in Tkinter callback
Traceback (most recent call last):
  File "/usr/local/lib/python2.0/lib-tk/Tkinter.py", line 1287, in
__call__
    return apply(self.func, args)
  File "<stdin>", line 51, in quit
AttributeError: 'Dialog' instance has no attribute 'num'

I fire up the interpreter:

Python 2.0 (#6, Apr 15 2001, 09:21:33)
[GCC 2.95.3 19991030 (prerelease)] on linux2
Type "copyright", "credits" or "license" for more information.
>>> from Dialog import Dialog
>>> ans = Dialog( title   = 'Verify quit',
...     text = 'Are you sure you want to quit?',
...     bitmap='question',
...     default=1,
...     strings=('Yes','No'))
>>> ans.num
0
>>>

So, under what conditions does a Dialog instance not have an attribute
of 'num'?

--
 Brian Smith
 greybria at direct.ca
 http://mypage.direct.ca/g/greybria