[Tutor] using -i flag with '''if __name__ == "__main__":'''

[Terry Carroll]

I've often found it convenient to run a Python program I'm developing with 
the -i flag. I find it convenient to use as a post-mortem as it hits bugs, 
or to explore data structures.

I've recently started using the construct 

  if __name__ == "__main__":
     main()

And found I can't do the -i thing effectively any more.  What's a good 
equivalent approach?

To use a trivial example, if I have the following program (t2.py):

i = 0
k = 4/i
print i, k

I can do this:

C:\>python -i t2.py
Traceback (most recent call last):
  File "t2.py", line 2, in ?
    k = 4/i
ZeroDivisionError: integer division or modulo by zero
>>> i
0
>>>

But if the program is like this:

def main():
   i = 0
   k = 4/i
   print i, k

if __name__ == "__main__":
   main()

That won't work:

C:\>python -i t1.py
Traceback (most recent call last):
  File "t1.py", line 7, in ?
    main()
  File "t1.py", line 3, in main
    k = 4/i
ZeroDivisionError: integer division or modulo by zero
>>> i
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
NameError: name 'i' is not defined
>>>


I understand *why* it won't work; I'm just looking for a nice 
easy way to do the same sort of thing I used to do before I 
started using '''if __name__ == "__main__":'''