Mini Excel

No so small as the calculator, but small enough (120 lines of code).
It can do any Python expression as a formula, support cell reference and ranges.

Watch that "yield"

Assume you have a program:

def f():
   print "F"
   yield 1

if __name__ == "__main__":
   f()

and you run it, nothing is printed.
Then you comment out the "yield" statement, and F is printed out.

I actually went a filled a bug report. I need to know better than that :)

Raymond pointed out that in the first case, the yield statement causes the function to become a generator and nothing is being run until next is called.

This means Python is behaving as expected, however I'd wish for Python or Pychecker to have a GCC like statement with no effect warning.