simple date range iterator

date_range.py

from datetime import datetime, date, timedelta


class date_range(object):

    def __init__(self, since, until, step=timedelta(days=1)):
        assert isinstance(since, (datetime, date))
        assert isinstance(until, (datetime, date))
        assert isinstance(step, timedelta)

        self.since = since
        self.until = until
        self.step = step
        self.current = since - step

    def __iter__(self):
        return self

    def next(self):
        if self.current >= self.until:
            raise StopIteration()

        self.current += self.step

        if self.current > self.until:
            return self.until

        return self.current


def test():
    d_range = list(date_range(date(2000, 1, 1), date(2000, 1, 3)))
    e_range = [date(2000, 1, 1), date(2000, 1, 2), date(2000, 1, 3)]
    assert d_range == e_range, d_range

    d_range = list(date_range(
        date(2000, 1, 1),
        date(2000, 2, 3),
        timedelta(days=7)
    ))
    e_range = [
        date(2000, 1, 1),
        date(2000, 1, 8),
        date(2000, 1, 15),
        date(2000, 1, 22),
        date(2000, 1, 29),
        date(2000, 2, 3),
    ]
    assert d_range == e_range, d_range


if __name__ == '__main__':
    test()

I've added some stuff to my fork of this gist:

• A zero step value is caught as it could cause and infinite loop
• A negative step value can be used
• Getting since and until the wrong way around (since after until) is silently corrected