fizzbuzz.py

"""Simple fizzbuzz generator.

The game proceeds with players announcing numbers increasing
sequentially, except for multiples of 3 and 5:

    >>> usage = 'fizzbuzz 1 20'

    >>> from io import StringIO; stdout = StringIO()
    >>> main(usage.split(), stdout)
    >>> print(stdout.getvalue())
    ... #doctest: +ELLIPSIS
    1
    2
    fizz
    4
    buzz
    fizz
    7
    ...
    14
    fizzbuzz
    16
    ...

"""


def main(argv, stdout):
    [lo_, hi_] = argv[1:3]
    lo, hi = int(lo_), int(hi_)

    for word in fizzbuzz(lo, hi):
        print(word, file=stdout)


def fizzbuzz(lo, hi):
    """
    >>> list(fizzbuzz(1, 6))
    [1, 2, 'fizz', 4, 'buzz']
    """
    for n in range(lo, hi):
        if n % 3 == 0 and n % 5 == 0:
            yield "fizzbuzz"
        elif n % 3 == 0:
            yield "fizz"
        elif n % 5 == 0:
            yield "buzz"
        else:
            yield n


if __name__ == '__main__':
    def _script_io():
        from sys import argv, stdout

        main(argv, stdout)

    _script_io()

I browsed your article but did not understand why you introduce _script_io() instead of just use

if __name__ == '__main__':
  import sys
  main(sys.argv, sys.stdout)

because then sys would be visible at module scope and some function in the middle of the module could just refer to sys.stdin or sys.version or the like without having that authority passed in explicitly. That would violate ocap discipline, making the code hard to audit and test.

but yes, I neglected to explain that.

Okay, then I get it.

I suppose I could del _script_io before calling main() to avoid some risks.

This is still sort of voluntary compliance. Python is nearly impossible to completely secure. Only languages like monte, E, pony, and Joe-E actually enforce ocap discipline for us.

(did you delete this comment?) anyway... you might want to look at https://monte.readthedocs.io/en/latest/intro.html#object-capability-discipline

…

On Fri, Jul 26, 2019 at 8:21 AM Pablo Fernandez ***@***.***> wrote: What is ocap discipline? — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <https://gist.github.com/d58a04b154d44d46de9abcda84b2a2f0?email_source=notifications&email_token=AABE3SRNRPJTD2KD7FN4N6TQBL26FA5CNFSM4IG42MN2YY3PNVWWK3TUL52HS4DFVNDWS43UINXW23LFNZ2KUY3PNVWWK3TUL5UWJTQAFV7U6#gistcomment-2981711>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AABE3SXAUR6XBZH4RXXXJGTQBL26FANCNFSM4IG42MNQ> .

-- Dan Connolly http://www.madmode.com/

Yeah, found out that the explanation was in your post